From patchwork Tue Jun 11 00:21:37 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Houghton X-Patchwork-Id: 13692705 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1CAD0C27C5F for ; Tue, 11 Jun 2024 00:22:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:Message-ID: References:Mime-Version:In-Reply-To:Date:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; 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AJvYcCXMg5iwrR52kgTke50NtN+CP0IuPt0TlyYm9K9w5evnTFFP8JUmGfVfkyTa7IOZloBNXcHUsXkJUYkoSDq2mEF/syu6Mqhdnewqt7rCr21LeFoi7Z0= X-Gm-Message-State: AOJu0Yy3+YkDQBS/SlOtFMBz07+LbrB/+tc6vu6FHSUK/DjCCZxftui0 gniL/qgpMHVneD55GvEBPwrHksxarqvggGamI/UJH946SbDor8AAOaaD76A3snnGAj9rEI4NJqD vLhdvM2ScgMbsQofj6g== X-Google-Smtp-Source: AGHT+IEGsmdXMyxgJ1Cj/3hdc6/ErG88swxZnK/rdFuCwoqmhzkdtuuICPRcxc2axyqsks7ulwYmlzACcQfHnSLC X-Received: from jthoughton.c.googlers.com ([fda3:e722:ac3:cc00:14:4d90:c0a8:2a4f]) (user=jthoughton job=sendgmr) by 2002:a05:6902:1003:b0:dd9:20c1:85b6 with SMTP id 3f1490d57ef6-dfd9fcb617bmr288182276.2.1718065319751; Mon, 10 Jun 2024 17:21:59 -0700 (PDT) Date: Tue, 11 Jun 2024 00:21:37 +0000 In-Reply-To: <20240611002145.2078921-1-jthoughton@google.com> Mime-Version: 1.0 References: <20240611002145.2078921-1-jthoughton@google.com> X-Mailer: git-send-email 2.45.2.505.gda0bf45e8d-goog Message-ID: <20240611002145.2078921-2-jthoughton@google.com> Subject: [PATCH v5 1/9] KVM: Add lockless memslot walk to KVM From: James Houghton To: Andrew Morton , Paolo Bonzini Cc: Ankit Agrawal , Axel Rasmussen , Catalin Marinas , David Matlack , David Rientjes , James Houghton , James Morse , Jonathan Corbet , Marc Zyngier , Oliver Upton , Raghavendra Rao Ananta , Ryan Roberts , Sean Christopherson , Shaoqin Huang , Suzuki K Poulose , Wei Xu , Will Deacon , Yu Zhao , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240610_172203_555512_2D24439E X-CRM114-Status: GOOD ( 16.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Provide flexibility to the architecture to synchronize as optimally as they can instead of always taking the MMU lock for writing. Architectures that do their own locking must select CONFIG_KVM_MMU_NOTIFIER_YOUNG_LOCKLESS. The immediate application is to allow architectures to implement the test/clear_young MMU notifiers more cheaply. Suggested-by: Yu Zhao Signed-off-by: James Houghton --- include/linux/kvm_host.h | 1 + virt/kvm/Kconfig | 3 +++ virt/kvm/kvm_main.c | 26 +++++++++++++++++++------- 3 files changed, 23 insertions(+), 7 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 692c01e41a18..4d7c3e8632e6 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -266,6 +266,7 @@ struct kvm_gfn_range { gfn_t end; union kvm_mmu_notifier_arg arg; bool may_block; + bool lockless; }; bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range); bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range); diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index 29b73eedfe74..0404857c1702 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -97,6 +97,9 @@ config KVM_GENERIC_MMU_NOTIFIER select MMU_NOTIFIER bool +config KVM_MMU_NOTIFIER_YOUNG_LOCKLESS + bool + config KVM_GENERIC_MEMORY_ATTRIBUTES depends on KVM_GENERIC_MMU_NOTIFIER bool diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 14841acb8b95..d8fa0d617f12 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -558,6 +558,7 @@ struct kvm_mmu_notifier_range { on_lock_fn_t on_lock; bool flush_on_ret; bool may_block; + bool lockless; }; /* @@ -612,6 +613,10 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm, IS_KVM_NULL_FN(range->handler))) return r; + /* on_lock will never be called for lockless walks */ + if (WARN_ON_ONCE(range->lockless && !IS_KVM_NULL_FN(range->on_lock))) + return r; + idx = srcu_read_lock(&kvm->srcu); for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { @@ -643,15 +648,18 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm, gfn_range.start = hva_to_gfn_memslot(hva_start, slot); gfn_range.end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, slot); gfn_range.slot = slot; + gfn_range.lockless = range->lockless; if (!r.found_memslot) { r.found_memslot = true; - KVM_MMU_LOCK(kvm); - if (!IS_KVM_NULL_FN(range->on_lock)) - range->on_lock(kvm); - - if (IS_KVM_NULL_FN(range->handler)) - break; + if (!range->lockless) { + KVM_MMU_LOCK(kvm); + if (!IS_KVM_NULL_FN(range->on_lock)) + range->on_lock(kvm); + + if (IS_KVM_NULL_FN(range->handler)) + break; + } } r.ret |= range->handler(kvm, &gfn_range); } @@ -660,7 +668,7 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm, if (range->flush_on_ret && r.ret) kvm_flush_remote_tlbs(kvm); - if (r.found_memslot) + if (r.found_memslot && !range->lockless) KVM_MMU_UNLOCK(kvm); srcu_read_unlock(&kvm->srcu, idx); @@ -681,6 +689,8 @@ static __always_inline int kvm_handle_hva_range(struct mmu_notifier *mn, .on_lock = (void *)kvm_null_fn, .flush_on_ret = true, .may_block = false, + .lockless = + IS_ENABLED(CONFIG_KVM_MMU_NOTIFIER_YOUNG_LOCKLESS), }; return __kvm_handle_hva_range(kvm, &range).ret; @@ -699,6 +709,8 @@ static __always_inline int kvm_handle_hva_range_no_flush(struct mmu_notifier *mn .on_lock = (void *)kvm_null_fn, .flush_on_ret = false, .may_block = false, + .lockless = + IS_ENABLED(CONFIG_KVM_MMU_NOTIFIER_YOUNG_LOCKLESS), }; return __kvm_handle_hva_range(kvm, &range).ret; From patchwork Tue Jun 11 00:21:38 2024 Content-Type: text/plain; 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AJvYcCV36Go+cMaf3d5nR1aUj77xTIn3y9mUBjL+Je/XqGFmsnzFY5UkXVprc3JqwA/68sayzez5iayAM2B8hHYUmtzui3H0ZJNv/LrAj2SwmvG9g+9+25M= X-Gm-Message-State: AOJu0YyjrPSLIR7wqfXzCxPJntSlg9V+Hyh4ysehGU6ywUtCDubXdHZD O6txVnLE24y4gtDYUq9g6FpU8XlHCYxKweaDhZxdZPqU2bXrAjLVsbfKqbUtD+ARnmXWqejNAtO BagSaA+F6l8PJ2Js4OQ== X-Google-Smtp-Source: AGHT+IH/lTyMKkfYBTfkyMLpzJLgvdaQf1eZ0iJ8gYjDqr0mKX19Ny4cIhX4/ZVJH2rhH9pB2RhhAEM9xGJV6D5s X-Received: from jthoughton.c.googlers.com ([fda3:e722:ac3:cc00:14:4d90:c0a8:2a4f]) (user=jthoughton job=sendgmr) by 2002:a05:690c:f12:b0:62c:ea0b:a44e with SMTP id 00721157ae682-62cea0ba712mr29004557b3.2.1718065320553; Mon, 10 Jun 2024 17:22:00 -0700 (PDT) Date: Tue, 11 Jun 2024 00:21:38 +0000 In-Reply-To: <20240611002145.2078921-1-jthoughton@google.com> Mime-Version: 1.0 References: <20240611002145.2078921-1-jthoughton@google.com> X-Mailer: git-send-email 2.45.2.505.gda0bf45e8d-goog Message-ID: <20240611002145.2078921-3-jthoughton@google.com> Subject: [PATCH v5 2/9] KVM: x86: Relax locking for kvm_test_age_gfn and kvm_age_gfn From: James Houghton To: Andrew Morton , Paolo Bonzini Cc: Ankit Agrawal , Axel Rasmussen , Catalin Marinas , David Matlack , David Rientjes , James Houghton , James Morse , Jonathan Corbet , Marc Zyngier , Oliver Upton , Raghavendra Rao Ananta , Ryan Roberts , Sean Christopherson , Shaoqin Huang , Suzuki K Poulose , Wei Xu , Will Deacon , Yu Zhao , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240610_172203_870294_0B16C016 X-CRM114-Status: GOOD ( 26.79 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Walk the TDP MMU in an RCU read-side critical section. This requires a way to do RCU-safe walking of the tdp_mmu_roots; do this with a new macro. The PTE modifications are now done atomically, and kvm_tdp_mmu_spte_need_atomic_write() has been updated to account for the fact that kvm_age_gfn can now lockless update the accessed bit and the R/X bits). If the cmpxchg for marking the spte for access tracking fails, we simply retry if the spte is still a leaf PTE. If it isn't, we return false to continue the walk. Harvesting age information from the shadow MMU is still done while holding the MMU write lock. Suggested-by: Yu Zhao Signed-off-by: James Houghton --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/Kconfig | 1 + arch/x86/kvm/mmu/mmu.c | 10 ++++- arch/x86/kvm/mmu/tdp_iter.h | 27 +++++++------ arch/x86/kvm/mmu/tdp_mmu.c | 67 +++++++++++++++++++++++++-------- 5 files changed, 77 insertions(+), 29 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index f8ca74e7678f..011c8eb7c8d3 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1438,6 +1438,7 @@ struct kvm_arch { * tdp_mmu_page set. * * For reads, this list is protected by: + * RCU alone or * the MMU lock in read mode + RCU or * the MMU lock in write mode * diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index fec95a770270..9dda7f8c72ed 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -23,6 +23,7 @@ config KVM depends on X86_LOCAL_APIC select KVM_COMMON select KVM_GENERIC_MMU_NOTIFIER + select KVM_MMU_NOTIFIER_YOUNG_LOCKLESS select HAVE_KVM_IRQCHIP select HAVE_KVM_PFNCACHE select HAVE_KVM_DIRTY_RING_TSO diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 8d74bdef68c1..51061f1fb3d1 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -1633,8 +1633,11 @@ bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { bool young = false; - if (kvm_memslots_have_rmaps(kvm)) + if (kvm_memslots_have_rmaps(kvm)) { + write_lock(&kvm->mmu_lock); young = kvm_handle_gfn_range(kvm, range, kvm_age_rmap); + write_unlock(&kvm->mmu_lock); + } if (tdp_mmu_enabled) young |= kvm_tdp_mmu_age_gfn_range(kvm, range); @@ -1646,8 +1649,11 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { bool young = false; - if (kvm_memslots_have_rmaps(kvm)) + if (kvm_memslots_have_rmaps(kvm)) { + write_lock(&kvm->mmu_lock); young = kvm_handle_gfn_range(kvm, range, kvm_test_age_rmap); + write_unlock(&kvm->mmu_lock); + } if (tdp_mmu_enabled) young |= kvm_tdp_mmu_test_age_gfn(kvm, range); diff --git a/arch/x86/kvm/mmu/tdp_iter.h b/arch/x86/kvm/mmu/tdp_iter.h index 2880fd392e0c..510936a8455a 100644 --- a/arch/x86/kvm/mmu/tdp_iter.h +++ b/arch/x86/kvm/mmu/tdp_iter.h @@ -25,6 +25,13 @@ static inline u64 kvm_tdp_mmu_write_spte_atomic(tdp_ptep_t sptep, u64 new_spte) return xchg(rcu_dereference(sptep), new_spte); } +static inline u64 tdp_mmu_clear_spte_bits_atomic(tdp_ptep_t sptep, u64 mask) +{ + atomic64_t *sptep_atomic = (atomic64_t *)rcu_dereference(sptep); + + return (u64)atomic64_fetch_and(~mask, sptep_atomic); +} + static inline void __kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 new_spte) { KVM_MMU_WARN_ON(is_ept_ve_possible(new_spte)); @@ -32,10 +39,11 @@ static inline void __kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 new_spte) } /* - * SPTEs must be modified atomically if they are shadow-present, leaf - * SPTEs, and have volatile bits, i.e. has bits that can be set outside - * of mmu_lock. The Writable bit can be set by KVM's fast page fault - * handler, and Accessed and Dirty bits can be set by the CPU. + * SPTEs must be modified atomically if they have bits that can be set outside + * of the mmu_lock. This can happen for any shadow-present leaf SPTEs, as the + * Writable bit can be set by KVM's fast page fault handler, the Accessed and + * Dirty bits can be set by the CPU, and the Accessed and R/X bits can be + * cleared by age_gfn_range. * * Note, non-leaf SPTEs do have Accessed bits and those bits are * technically volatile, but KVM doesn't consume the Accessed bit of @@ -46,8 +54,7 @@ static inline void __kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 new_spte) static inline bool kvm_tdp_mmu_spte_need_atomic_write(u64 old_spte, int level) { return is_shadow_present_pte(old_spte) && - is_last_spte(old_spte, level) && - spte_has_volatile_bits(old_spte); + is_last_spte(old_spte, level); } static inline u64 kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 old_spte, @@ -63,12 +70,8 @@ static inline u64 kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 old_spte, static inline u64 tdp_mmu_clear_spte_bits(tdp_ptep_t sptep, u64 old_spte, u64 mask, int level) { - atomic64_t *sptep_atomic; - - if (kvm_tdp_mmu_spte_need_atomic_write(old_spte, level)) { - sptep_atomic = (atomic64_t *)rcu_dereference(sptep); - return (u64)atomic64_fetch_and(~mask, sptep_atomic); - } + if (kvm_tdp_mmu_spte_need_atomic_write(old_spte, level)) + return tdp_mmu_clear_spte_bits_atomic(sptep, mask); __kvm_tdp_mmu_write_spte(sptep, old_spte & ~mask); return old_spte; diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 36539c1b36cd..46abd04914c2 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -29,6 +29,11 @@ static __always_inline bool kvm_lockdep_assert_mmu_lock_held(struct kvm *kvm, return true; } +static __always_inline bool kvm_lockdep_assert_rcu_read_lock_held(void) +{ + WARN_ON_ONCE(!rcu_read_lock_held()); + return true; +} void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm) { @@ -178,6 +183,15 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, ((_only_valid) && (_root)->role.invalid))) { \ } else +/* + * Iterate over all TDP MMU roots in an RCU read-side critical section. + */ +#define for_each_tdp_mmu_root_rcu(_kvm, _root, _as_id) \ + list_for_each_entry_rcu(_root, &_kvm->arch.tdp_mmu_roots, link) \ + if (kvm_lockdep_assert_rcu_read_lock_held() && \ + (_as_id >= 0 && kvm_mmu_page_as_id(_root) != _as_id)) { \ + } else + #define for_each_tdp_mmu_root(_kvm, _root, _as_id) \ __for_each_tdp_mmu_root(_kvm, _root, _as_id, false) @@ -1223,6 +1237,27 @@ static __always_inline bool kvm_tdp_mmu_handle_gfn(struct kvm *kvm, return ret; } +static __always_inline bool kvm_tdp_mmu_handle_gfn_lockless( + struct kvm *kvm, + struct kvm_gfn_range *range, + tdp_handler_t handler) +{ + struct kvm_mmu_page *root; + struct tdp_iter iter; + bool ret = false; + + rcu_read_lock(); + + for_each_tdp_mmu_root_rcu(kvm, root, range->slot->as_id) { + tdp_root_for_each_leaf_pte(iter, root, range->start, range->end) + ret |= handler(kvm, &iter, range); + } + + rcu_read_unlock(); + + return ret; +} + /* * Mark the SPTEs range of GFNs [start, end) unaccessed and return non-zero * if any of the GFNs in the range have been accessed. @@ -1236,28 +1271,30 @@ static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter, { u64 new_spte; +retry: /* If we have a non-accessed entry we don't need to change the pte. */ if (!is_accessed_spte(iter->old_spte)) return false; if (spte_ad_enabled(iter->old_spte)) { - iter->old_spte = tdp_mmu_clear_spte_bits(iter->sptep, - iter->old_spte, - shadow_accessed_mask, - iter->level); + iter->old_spte = tdp_mmu_clear_spte_bits_atomic(iter->sptep, + shadow_accessed_mask); new_spte = iter->old_spte & ~shadow_accessed_mask; } else { - /* - * Capture the dirty status of the page, so that it doesn't get - * lost when the SPTE is marked for access tracking. - */ + new_spte = mark_spte_for_access_track(iter->old_spte); + if (__tdp_mmu_set_spte_atomic(iter, new_spte)) { + /* + * The cmpxchg failed. If the spte is still a + * last-level spte, we can safely retry. + */ + if (is_shadow_present_pte(iter->old_spte) && + is_last_spte(iter->old_spte, iter->level)) + goto retry; + /* Otherwise, continue walking. */ + return false; + } if (is_writable_pte(iter->old_spte)) kvm_set_pfn_dirty(spte_to_pfn(iter->old_spte)); - - new_spte = mark_spte_for_access_track(iter->old_spte); - iter->old_spte = kvm_tdp_mmu_write_spte(iter->sptep, - iter->old_spte, new_spte, - iter->level); } trace_kvm_tdp_mmu_spte_changed(iter->as_id, iter->gfn, iter->level, @@ -1267,7 +1304,7 @@ static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter, bool kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) { - return kvm_tdp_mmu_handle_gfn(kvm, range, age_gfn_range); + return kvm_tdp_mmu_handle_gfn_lockless(kvm, range, age_gfn_range); } static bool test_age_gfn(struct kvm *kvm, struct tdp_iter *iter, @@ -1278,7 +1315,7 @@ static bool test_age_gfn(struct kvm *kvm, struct tdp_iter *iter, bool kvm_tdp_mmu_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { - return kvm_tdp_mmu_handle_gfn(kvm, range, test_age_gfn); 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AJvYcCUAK9ee72pLV8HRg0jr9kRmKmZ7OOo+MJEfRapS09nvBdcKLC8gu+mfJ6bYW6YcqzPoB+7Q7JHq1j3pIH7qDMPgkI3HtqythZRd+VfBiFx9mjTjzaY= X-Gm-Message-State: AOJu0YyPM1y1biu8mftWhjNaKtrvO1lRhCOnzqcYtdyKhD2VXC8wxwkf 5QIGA+GEnm6DIGI8plPAAqYeGhSKvd+VCAyFtPogQjlQUhbQIIwoQeFPAUTVQ0VwUfxanucOWrs FbA4A5CNKifrn7l8F+w== X-Google-Smtp-Source: AGHT+IEkfpXJhDpYSXj2zWTmc5g4eYevyTxa6JBBNjQgHAzXAToudTEtQid77N/s8K4jHcfyWfR4EDBUwm2H5zD1 X-Received: from jthoughton.c.googlers.com ([fda3:e722:ac3:cc00:14:4d90:c0a8:2a4f]) (user=jthoughton job=sendgmr) by 2002:a05:6902:100a:b0:df4:ece5:2720 with SMTP id 3f1490d57ef6-dfaf6608d72mr3353252276.13.1718065321541; Mon, 10 Jun 2024 17:22:01 -0700 (PDT) Date: Tue, 11 Jun 2024 00:21:39 +0000 In-Reply-To: <20240611002145.2078921-1-jthoughton@google.com> Mime-Version: 1.0 References: <20240611002145.2078921-1-jthoughton@google.com> X-Mailer: git-send-email 2.45.2.505.gda0bf45e8d-goog Message-ID: <20240611002145.2078921-4-jthoughton@google.com> Subject: [PATCH v5 3/9] KVM: arm64: Relax locking for kvm_test_age_gfn and kvm_age_gfn From: James Houghton To: Andrew Morton , Paolo Bonzini Cc: Ankit Agrawal , Axel Rasmussen , Catalin Marinas , David Matlack , David Rientjes , James Houghton , James Morse , Jonathan Corbet , Marc Zyngier , Oliver Upton , Raghavendra Rao Ananta , Ryan Roberts , Sean Christopherson , Shaoqin Huang , Suzuki K Poulose , Wei Xu , Will Deacon , Yu Zhao , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240610_172204_803970_D895BFF0 X-CRM114-Status: GOOD ( 17.00 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Replace the MMU write locks (taken in the memslot iteration loop) for read locks. Grabbing the read lock instead of the write lock is safe because the only requirement we have is that the stage-2 page tables do not get deallocated while we are walking them. The stage2_age_walker() callback is safe to race with itself; update the comment to reflect the synchronization change. Signed-off-by: James Houghton --- arch/arm64/kvm/Kconfig | 1 + arch/arm64/kvm/hyp/pgtable.c | 15 +++++++++------ arch/arm64/kvm/mmu.c | 26 ++++++++++++++++++++------ 3 files changed, 30 insertions(+), 12 deletions(-) diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index 58f09370d17e..7a1af8141c0e 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -22,6 +22,7 @@ menuconfig KVM select KVM_COMMON select KVM_GENERIC_HARDWARE_ENABLING select KVM_GENERIC_MMU_NOTIFIER + select KVM_MMU_NOTIFIER_YOUNG_LOCKLESS select HAVE_KVM_CPU_RELAX_INTERCEPT select KVM_MMIO select KVM_GENERIC_DIRTYLOG_READ_PROTECT diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index 9e2bbee77491..b1b0f7148cff 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -1319,10 +1319,10 @@ static int stage2_age_walker(const struct kvm_pgtable_visit_ctx *ctx, data->young = true; /* - * stage2_age_walker() is always called while holding the MMU lock for - * write, so this will always succeed. Nonetheless, this deliberately - * follows the race detection pattern of the other stage-2 walkers in - * case the locking mechanics of the MMU notifiers is ever changed. + * This walk may not be exclusive; the PTE is permitted to change + * from under us. If there is a race to update this PTE, then the + * GFN is most likely young, so failing to clear the AF is likely + * to be inconsequential. */ if (data->mkold && !stage2_try_set_pte(ctx, new)) return -EAGAIN; @@ -1345,10 +1345,13 @@ bool kvm_pgtable_stage2_test_clear_young(struct kvm_pgtable *pgt, u64 addr, struct kvm_pgtable_walker walker = { .cb = stage2_age_walker, .arg = &data, - .flags = KVM_PGTABLE_WALK_LEAF, + .flags = KVM_PGTABLE_WALK_LEAF | + KVM_PGTABLE_WALK_SHARED, }; + int r; - WARN_ON(kvm_pgtable_walk(pgt, addr, size, &walker)); + r = kvm_pgtable_walk(pgt, addr, size, &walker); + WARN_ON(r && r != -EAGAIN); return data.young; } diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 8bcab0cc3fe9..a62c27a347ed 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1773,25 +1773,39 @@ bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { u64 size = (range->end - range->start) << PAGE_SHIFT; + bool young = false; + + read_lock(&kvm->mmu_lock); if (!kvm->arch.mmu.pgt) return false; - return kvm_pgtable_stage2_test_clear_young(kvm->arch.mmu.pgt, - range->start << PAGE_SHIFT, - size, true); + young = kvm_pgtable_stage2_test_clear_young(kvm->arch.mmu.pgt, + range->start << PAGE_SHIFT, + size, true); + +out: + read_unlock(&kvm->mmu_lock); + return young; } bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { u64 size = (range->end - range->start) << PAGE_SHIFT; + bool young = false; + + read_lock(&kvm->mmu_lock); if (!kvm->arch.mmu.pgt) return false; - return kvm_pgtable_stage2_test_clear_young(kvm->arch.mmu.pgt, - range->start << PAGE_SHIFT, - size, false); + young = kvm_pgtable_stage2_test_clear_young(kvm->arch.mmu.pgt, + range->start << PAGE_SHIFT, + size, false); + +out: + read_unlock(&kvm->mmu_lock); + return young; } phys_addr_t kvm_mmu_get_httbr(void) From patchwork Tue Jun 11 00:21:40 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Houghton X-Patchwork-Id: 13692709 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A91C1C27C4F for ; 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Mon, 10 Jun 2024 17:22:02 -0700 (PDT) Date: Tue, 11 Jun 2024 00:21:40 +0000 In-Reply-To: <20240611002145.2078921-1-jthoughton@google.com> Mime-Version: 1.0 References: <20240611002145.2078921-1-jthoughton@google.com> X-Mailer: git-send-email 2.45.2.505.gda0bf45e8d-goog Message-ID: <20240611002145.2078921-5-jthoughton@google.com> Subject: [PATCH v5 4/9] mm: Add test_clear_young_fast_only MMU notifier From: James Houghton To: Andrew Morton , Paolo Bonzini Cc: Ankit Agrawal , Axel Rasmussen , Catalin Marinas , David Matlack , David Rientjes , James Houghton , James Morse , Jonathan Corbet , Marc Zyngier , Oliver Upton , Raghavendra Rao Ananta , Ryan Roberts , Sean Christopherson , Shaoqin Huang , Suzuki K Poulose , Wei Xu , Will Deacon , Yu Zhao , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240610_172206_023423_FE10DC1C X-CRM114-Status: GOOD ( 18.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This new notifier is for multi-gen LRU specifically, as it wants to be able to get and clear age information from secondary MMUs only if it can be done "fast". By having this notifier specifically created for MGLRU, what "fast" means comes down to what is "fast" enough to improve MGLRU's ability to reclaim most of the time. Signed-off-by: James Houghton --- include/linux/mmu_notifier.h | 50 ++++++++++++++++++++++++++++++++++++ mm/mmu_notifier.c | 26 +++++++++++++++++++ 2 files changed, 76 insertions(+) diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h index d39ebb10caeb..2655d841a409 100644 --- a/include/linux/mmu_notifier.h +++ b/include/linux/mmu_notifier.h @@ -61,6 +61,15 @@ enum mmu_notifier_event { #define MMU_NOTIFIER_RANGE_BLOCKABLE (1 << 0) +/* + * Bits in the return value for test_clear_young_fast_only. + * + * MMU_NOTIFIER_FAST_YOUNG: notifier succeeded, secondary MMU reports young. + * MMU_NOTIFIER_FAST_FAILED: notifier failed. + */ +#define MMU_NOTIFIER_FAST_YOUNG (1 << 0) +#define MMU_NOTIFIER_FAST_FAILED (1 << 1) + struct mmu_notifier_ops { /* * Called either by mmu_notifier_unregister or when the mm is @@ -122,6 +131,24 @@ struct mmu_notifier_ops { struct mm_struct *mm, unsigned long address); + /* + * test_clear_young_fast_only is called to check (and optionally clear) + * the young/accessed bitflag in the secondary pte such that the + * secondary MMU must implement it in a way that will not significantly + * disrupt other MMU operations. In other words, speed is more + * important than accuracy. + * + * Returns MMU_NOTIFIER_FAST_YOUNG if the secondary pte(s) were young. + * Returns MMU_NOTIFIER_FAST_FAILED if the secondary MMU could not do + * an accurate fast-only test and/or clear of the young/accessed + * flag. + */ + int (*test_clear_young_fast_only)(struct mmu_notifier *subscription, + struct mm_struct *mm, + unsigned long start, + unsigned long end, + bool clear); + /* * invalidate_range_start() and invalidate_range_end() must be * paired and are called only when the mmap_lock and/or the @@ -383,6 +410,10 @@ extern int __mmu_notifier_clear_young(struct mm_struct *mm, unsigned long end); extern int __mmu_notifier_test_young(struct mm_struct *mm, unsigned long address); +extern int __mmu_notifier_test_clear_young_fast_only(struct mm_struct *mm, + unsigned long start, + unsigned long end, + bool clear); extern int __mmu_notifier_invalidate_range_start(struct mmu_notifier_range *r); extern void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *r); extern void __mmu_notifier_arch_invalidate_secondary_tlbs(struct mm_struct *mm, @@ -428,6 +459,17 @@ static inline int mmu_notifier_test_young(struct mm_struct *mm, return 0; } +static inline int mmu_notifier_test_clear_young_fast_only(struct mm_struct *mm, + unsigned long start, + unsigned long end, + bool clear) +{ + if (mm_has_notifiers(mm)) + return __mmu_notifier_test_clear_young_fast_only(mm, start, end, + clear); + return 0; +} + static inline void mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range) { @@ -612,6 +654,14 @@ static inline int mmu_notifier_test_young(struct mm_struct *mm, return 0; } +static inline int mmu_notifier_test_clear_young_fast_only(struct mm_struct *mm, + unsigned long start, + unsigned long end, + bool clear) +{ + return 0; +} + static inline void mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range) { diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c index 8982e6139d07..7b77ad6cf833 100644 --- a/mm/mmu_notifier.c +++ b/mm/mmu_notifier.c @@ -424,6 +424,32 @@ int __mmu_notifier_test_young(struct mm_struct *mm, return young; } +int __mmu_notifier_test_clear_young_fast_only(struct mm_struct *mm, + unsigned long start, + unsigned long end, + bool clear) +{ + struct mmu_notifier *subscription; + int ret = 0, id; + + id = srcu_read_lock(&srcu); + hlist_for_each_entry_rcu(subscription, + &mm->notifier_subscriptions->list, hlist, + srcu_read_lock_held(&srcu)) { + if (subscription->ops->test_clear_young_fast_only) { + ret = subscription->ops->test_clear_young_fast_only( + subscription, mm, start, end, clear); + if (ret & MMU_NOTIFIER_FAST_FAILED) + break; + if (!clear && (ret & MMU_NOTIFIER_FAST_YOUNG)) + break; + } + } + srcu_read_unlock(&srcu, id); + + return ret; +} + static int mn_itree_invalidate(struct mmu_notifier_subscriptions *subscriptions, const struct mmu_notifier_range *range) { From patchwork Tue Jun 11 00:21:41 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Houghton X-Patchwork-Id: 13692708 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8165BC27C4F for ; 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Mon, 10 Jun 2024 17:22:03 -0700 (PDT) Date: Tue, 11 Jun 2024 00:21:41 +0000 In-Reply-To: <20240611002145.2078921-1-jthoughton@google.com> Mime-Version: 1.0 References: <20240611002145.2078921-1-jthoughton@google.com> X-Mailer: git-send-email 2.45.2.505.gda0bf45e8d-goog Message-ID: <20240611002145.2078921-6-jthoughton@google.com> Subject: [PATCH v5 5/9] KVM: Add kvm_fast_age_gfn and kvm_fast_test_age_gfn From: James Houghton To: Andrew Morton , Paolo Bonzini Cc: Ankit Agrawal , Axel Rasmussen , Catalin Marinas , David Matlack , David Rientjes , James Houghton , James Morse , Jonathan Corbet , Marc Zyngier , Oliver Upton , Raghavendra Rao Ananta , Ryan Roberts , Sean Christopherson , Shaoqin Huang , Suzuki K Poulose , Wei Xu , Will Deacon , Yu Zhao , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240610_172206_521911_030AC0E8 X-CRM114-Status: GOOD ( 16.37 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Provide the basics for allowing architectures to implement mmu_notifier_test_clear_young_fast_only(). Add CONFIG_HAVE_KVM_YOUNG_FAST_ONLY_NOTIFIER that architectures will set if they implement the fast-only notifier. kvm_fast_age_gfn and kvm_fast_test_age_gfn both need to support returning a tri-state state of: 1. fast && young, 2. fast && !young, 3. !fast This could be done by making gfn_handler_t return int, but that would mean a lot of churn. Instead, include a new kvm_mmu_notifier_arg 'bool *failed' for kvm_fast_{test,}_age_gfn to optionally use. Signed-off-by: James Houghton --- include/linux/kvm_host.h | 7 ++++++ include/trace/events/kvm.h | 22 ++++++++++++++++++ virt/kvm/Kconfig | 4 ++++ virt/kvm/kvm_main.c | 47 ++++++++++++++++++++++++++++++-------- 4 files changed, 71 insertions(+), 9 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 4d7c3e8632e6..e4efeba51222 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -258,6 +258,9 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu); #ifdef CONFIG_KVM_GENERIC_MMU_NOTIFIER union kvm_mmu_notifier_arg { unsigned long attributes; +#ifdef CONFIG_HAVE_KVM_YOUNG_FAST_ONLY_NOTIFIER + bool *failed; +#endif }; struct kvm_gfn_range { @@ -271,7 +274,11 @@ struct kvm_gfn_range { bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range); bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range); bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range); +#ifdef CONFIG_HAVE_KVM_YOUNG_FAST_ONLY_NOTIFIER +bool kvm_fast_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range); +bool kvm_fast_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range); #endif +#endif /* CONFIG_KVM_GENERIC_MMU_NOTIFIER */ enum { OUTSIDE_GUEST_MODE, diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h index 74e40d5d4af4..7ba6c35c2426 100644 --- a/include/trace/events/kvm.h +++ b/include/trace/events/kvm.h @@ -489,6 +489,28 @@ TRACE_EVENT(kvm_test_age_hva, TP_printk("mmu notifier test age hva: %#016lx", __entry->hva) ); +TRACE_EVENT(kvm_fast_test_age_hva, + TP_PROTO(unsigned long start, unsigned long end, bool clear), + TP_ARGS(start, end, clear), + + TP_STRUCT__entry( + __field( unsigned long, start ) + __field( unsigned long, end ) + __field( bool, clear ) + ), + + TP_fast_assign( + __entry->start = start; + __entry->end = end; + __entry->clear = clear; + ), + + TP_printk("mmu notifier fast test age: hva: %#016lx -- %#016lx " + "clear: %d", + __entry->start, __entry->end, + __entry->clear) +); + #endif /* _TRACE_KVM_MAIN_H */ /* This part must be outside protection */ diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index 0404857c1702..77ac680af60c 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -100,6 +100,10 @@ config KVM_GENERIC_MMU_NOTIFIER config KVM_MMU_NOTIFIER_YOUNG_LOCKLESS bool +config HAVE_KVM_YOUNG_FAST_ONLY_NOTIFIER + select KVM_GENERIC_MMU_NOTIFIER + bool + config KVM_GENERIC_MEMORY_ATTRIBUTES depends on KVM_GENERIC_MMU_NOTIFIER bool diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index d8fa0d617f12..aa930a8b903f 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -699,7 +699,8 @@ static __always_inline int kvm_handle_hva_range(struct mmu_notifier *mn, static __always_inline int kvm_handle_hva_range_no_flush(struct mmu_notifier *mn, unsigned long start, unsigned long end, - gfn_handler_t handler) + gfn_handler_t handler, + bool *failed) { struct kvm *kvm = mmu_notifier_to_kvm(mn); const struct kvm_mmu_notifier_range range = { @@ -711,6 +712,7 @@ static __always_inline int kvm_handle_hva_range_no_flush(struct mmu_notifier *mn .may_block = false, .lockless = IS_ENABLED(CONFIG_KVM_MMU_NOTIFIER_YOUNG_LOCKLESS), + .arg.failed = failed, }; return __kvm_handle_hva_range(kvm, &range).ret; @@ -901,7 +903,7 @@ static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn, * cadence. If we find this inaccurate, we might come up with a * more sophisticated heuristic later. */ - return kvm_handle_hva_range_no_flush(mn, start, end, kvm_age_gfn); + return kvm_handle_hva_range_no_flush(mn, start, end, kvm_age_gfn, NULL); } static int kvm_mmu_notifier_test_young(struct mmu_notifier *mn, @@ -911,9 +913,32 @@ static int kvm_mmu_notifier_test_young(struct mmu_notifier *mn, trace_kvm_test_age_hva(address); return kvm_handle_hva_range_no_flush(mn, address, address + 1, - kvm_test_age_gfn); + kvm_test_age_gfn, NULL); } +#ifdef CONFIG_HAVE_KVM_YOUNG_FAST_ONLY_NOTIFIER +static int kvm_mmu_notifier_test_clear_young_fast_only(struct mmu_notifier *mn, + struct mm_struct *mm, + unsigned long start, + unsigned long end, + bool clear) +{ + gfn_handler_t handler; + bool failed = false, young; + + trace_kvm_fast_test_age_hva(start, end, clear); + + handler = clear ? kvm_fast_age_gfn : kvm_fast_test_age_gfn; + + young = kvm_handle_hva_range_no_flush(mn, start, end, handler, &failed); + + if (failed) + return MMU_NOTIFIER_FAST_FAILED; + + return young ? MMU_NOTIFIER_FAST_YOUNG : 0; +} +#endif + static void kvm_mmu_notifier_release(struct mmu_notifier *mn, struct mm_struct *mm) { @@ -926,12 +951,16 @@ static void kvm_mmu_notifier_release(struct mmu_notifier *mn, } static const struct mmu_notifier_ops kvm_mmu_notifier_ops = { - .invalidate_range_start = kvm_mmu_notifier_invalidate_range_start, - .invalidate_range_end = kvm_mmu_notifier_invalidate_range_end, - .clear_flush_young = kvm_mmu_notifier_clear_flush_young, - .clear_young = kvm_mmu_notifier_clear_young, - .test_young = kvm_mmu_notifier_test_young, - .release = kvm_mmu_notifier_release, + .invalidate_range_start = kvm_mmu_notifier_invalidate_range_start, + .invalidate_range_end = kvm_mmu_notifier_invalidate_range_end, + .clear_flush_young = kvm_mmu_notifier_clear_flush_young, + .clear_young = kvm_mmu_notifier_clear_young, + .test_young = kvm_mmu_notifier_test_young, +#ifdef CONFIG_HAVE_KVM_YOUNG_FAST_ONLY_NOTIFIER + .test_clear_young_fast_only = + kvm_mmu_notifier_test_clear_young_fast_only, +#endif + .release = kvm_mmu_notifier_release, }; 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AJvYcCVQ4y5z3qMwthUta585KF8p/D9COhuUpnLgKtEPgq94XKBBuYKvQ0lDLYNabjUTZfxBnr0dmWaWRYqRjMLG5USVFB0RACy0qAav4gqggKGGdYmf1GU= X-Gm-Message-State: AOJu0Yxu/zexLfoN6G48DMG2m+mZZCCmvuKxa1hscNg12CKOirCPyhiY 7wLiCXjOEiABkRPtVgX9YyDOXWmnj9mcMSY9DKz62WNNTaehe8toLWryU939Rro2uLYTM6M9Rq5 mADoHAONNDvMnXITa/w== X-Google-Smtp-Source: AGHT+IGdrDSzxMWV88JW0LA6UnAEJXd+QZJzNBe66poa1GZZ236cqaZmaxZKOwtkV9plz4I87xyLdQPCAlnoV8zg X-Received: from jthoughton.c.googlers.com ([fda3:e722:ac3:cc00:14:4d90:c0a8:2a4f]) (user=jthoughton job=sendgmr) by 2002:a05:690c:38b:b0:627:7563:95b1 with SMTP id 00721157ae682-62cd5652459mr33516247b3.5.1718065324168; Mon, 10 Jun 2024 17:22:04 -0700 (PDT) Date: Tue, 11 Jun 2024 00:21:42 +0000 In-Reply-To: <20240611002145.2078921-1-jthoughton@google.com> Mime-Version: 1.0 References: <20240611002145.2078921-1-jthoughton@google.com> X-Mailer: git-send-email 2.45.2.505.gda0bf45e8d-goog Message-ID: <20240611002145.2078921-7-jthoughton@google.com> Subject: [PATCH v5 6/9] KVM: x86: Move tdp_mmu_enabled and shadow_accessed_mask From: James Houghton To: Andrew Morton , Paolo Bonzini Cc: Ankit Agrawal , Axel Rasmussen , Catalin Marinas , David Matlack , David Rientjes , James Houghton , James Morse , Jonathan Corbet , Marc Zyngier , Oliver Upton , Raghavendra Rao Ananta , Ryan Roberts , Sean Christopherson , Shaoqin Huang , Suzuki K Poulose , Wei Xu , Will Deacon , Yu Zhao , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240610_172208_211988_641D8830 X-CRM114-Status: GOOD ( 10.60 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Yu Zhao tdp_mmu_enabled and shadow_accessed_mask are needed to implement kvm_arch_young_notifier_likely_fast(). Signed-off-by: Yu Zhao Signed-off-by: James Houghton --- arch/x86/include/asm/kvm_host.h | 6 ++++++ arch/x86/kvm/mmu.h | 6 ------ arch/x86/kvm/mmu/spte.h | 1 - 3 files changed, 6 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 011c8eb7c8d3..0dc1fa99cdbb 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1855,6 +1855,7 @@ struct kvm_arch_async_pf { extern u32 __read_mostly kvm_nr_uret_msrs; extern u64 __read_mostly host_efer; +extern u64 __read_mostly shadow_accessed_mask; extern bool __read_mostly allow_smaller_maxphyaddr; extern bool __read_mostly enable_apicv; extern struct kvm_x86_ops kvm_x86_ops; @@ -1960,6 +1961,11 @@ void kvm_fire_mask_notifiers(struct kvm *kvm, unsigned irqchip, unsigned pin, bool mask); extern bool tdp_enabled; +#ifdef CONFIG_X86_64 +extern bool tdp_mmu_enabled; +#else +#define tdp_mmu_enabled false +#endif u64 vcpu_tsc_khz(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 2e454316f2a2..267f72b065f5 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -271,12 +271,6 @@ static inline bool kvm_shadow_root_allocated(struct kvm *kvm) return smp_load_acquire(&kvm->arch.shadow_root_allocated); } -#ifdef CONFIG_X86_64 -extern bool tdp_mmu_enabled; -#else -#define tdp_mmu_enabled false -#endif - static inline bool kvm_memslots_have_rmaps(struct kvm *kvm) { return !tdp_mmu_enabled || kvm_shadow_root_allocated(kvm); diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h index 52fa004a1fbc..9ca6d80fb86c 100644 --- a/arch/x86/kvm/mmu/spte.h +++ b/arch/x86/kvm/mmu/spte.h @@ -172,7 +172,6 @@ extern u64 __read_mostly shadow_mmu_writable_mask; extern u64 __read_mostly shadow_nx_mask; extern u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */ extern u64 __read_mostly shadow_user_mask; -extern u64 __read_mostly shadow_accessed_mask; extern u64 __read_mostly shadow_dirty_mask; extern u64 __read_mostly shadow_mmio_value; extern u64 __read_mostly shadow_mmio_mask; From patchwork Tue Jun 11 00:21:43 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Houghton X-Patchwork-Id: 13692731 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D79FBC27C4F for ; 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Mon, 10 Jun 2024 17:22:04 -0700 (PDT) Date: Tue, 11 Jun 2024 00:21:43 +0000 In-Reply-To: <20240611002145.2078921-1-jthoughton@google.com> Mime-Version: 1.0 References: <20240611002145.2078921-1-jthoughton@google.com> X-Mailer: git-send-email 2.45.2.505.gda0bf45e8d-goog Message-ID: <20240611002145.2078921-8-jthoughton@google.com> Subject: [PATCH v5 7/9] KVM: x86: Implement kvm_fast_test_age_gfn and kvm_fast_age_gfn From: James Houghton To: Andrew Morton , Paolo Bonzini Cc: Ankit Agrawal , Axel Rasmussen , Catalin Marinas , David Matlack , David Rientjes , James Houghton , James Morse , Jonathan Corbet , Marc Zyngier , Oliver Upton , Raghavendra Rao Ananta , Ryan Roberts , Sean Christopherson , Shaoqin Huang , Suzuki K Poulose , Wei Xu , Will Deacon , Yu Zhao , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240610_172209_086493_F506C284 X-CRM114-Status: GOOD ( 16.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The fast-only notifier will only report an accurate result when the shadow MMU is not in use. Implement kvm_arch_young_notifier_likely_fast(), as MGLRU will check this function to see if it should even be attempting the fast-only notifier. We only want to attempt the notifier if there is a chance that it will succeed (i.e., that we're using the TDP MMU). Signed-off-by: James Houghton --- arch/x86/include/asm/kvm_host.h | 7 +++++ arch/x86/kvm/Kconfig | 1 + arch/x86/kvm/mmu/mmu.c | 50 ++++++++++++++++++++++++++++++--- 3 files changed, 54 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 0dc1fa99cdbb..ca2fbc162e51 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -2338,4 +2338,11 @@ int memslot_rmap_alloc(struct kvm_memory_slot *slot, unsigned long npages); */ #define KVM_EXIT_HYPERCALL_MBZ GENMASK_ULL(31, 1) +#define kvm_arch_young_notifier_likely_fast kvm_arch_young_notifier_likely_fast +static inline bool kvm_arch_young_notifier_likely_fast(void) +{ + return IS_ENABLED(CONFIG_X86_64) && tdp_mmu_enabled && + shadow_accessed_mask; +} + #endif /* _ASM_X86_KVM_HOST_H */ diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index 9dda7f8c72ed..84ae043c7d43 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -24,6 +24,7 @@ config KVM select KVM_COMMON select KVM_GENERIC_MMU_NOTIFIER select KVM_MMU_NOTIFIER_YOUNG_LOCKLESS + select HAVE_KVM_YOUNG_FAST_ONLY_NOTIFIER select HAVE_KVM_IRQCHIP select HAVE_KVM_PFNCACHE select HAVE_KVM_DIRTY_RING_TSO diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 51061f1fb3d1..ed50e78755ab 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -1629,11 +1629,15 @@ static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot, __rmap_add(vcpu->kvm, cache, slot, spte, gfn, access); } -bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +static int __kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range, + bool fast_only) { bool young = false; if (kvm_memslots_have_rmaps(kvm)) { + if (fast_only) + return -1; + write_lock(&kvm->mmu_lock); young = kvm_handle_gfn_range(kvm, range, kvm_age_rmap); write_unlock(&kvm->mmu_lock); @@ -1642,14 +1646,18 @@ bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) if (tdp_mmu_enabled) young |= kvm_tdp_mmu_age_gfn_range(kvm, range); - return young; + return (int)young; } -bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +static int __kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range, + bool fast_only) { bool young = false; if (kvm_memslots_have_rmaps(kvm)) { + if (fast_only) + return -1; + write_lock(&kvm->mmu_lock); young = kvm_handle_gfn_range(kvm, range, kvm_test_age_rmap); write_unlock(&kvm->mmu_lock); @@ -1658,7 +1666,41 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) if (tdp_mmu_enabled) young |= kvm_tdp_mmu_test_age_gfn(kvm, range); - return young; + return (int)young; +} + +bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +{ + return __kvm_age_gfn(kvm, range, false); +} + +bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +{ + return __kvm_test_age_gfn(kvm, range, false); +} + +bool kvm_fast_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +{ + int ret = __kvm_age_gfn(kvm, range, true); + + if (ret < 0) { + *range->arg.failed = true; + return false; + } + + return ret != 0; +} + +bool kvm_fast_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +{ + int ret = __kvm_test_age_gfn(kvm, range, true); + + if (ret < 0) { + *range->arg.failed = true; + return false; + } + + return ret != 0; } static void kvm_mmu_check_sptes_at_free(struct kvm_mmu_page *sp) From patchwork Tue Jun 11 00:21:44 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Houghton X-Patchwork-Id: 13692711 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6280CC27C55 for ; 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Mon, 10 Jun 2024 17:22:05 -0700 (PDT) Date: Tue, 11 Jun 2024 00:21:44 +0000 In-Reply-To: <20240611002145.2078921-1-jthoughton@google.com> Mime-Version: 1.0 References: <20240611002145.2078921-1-jthoughton@google.com> X-Mailer: git-send-email 2.45.2.505.gda0bf45e8d-goog Message-ID: <20240611002145.2078921-9-jthoughton@google.com> Subject: [PATCH v5 8/9] mm: multi-gen LRU: Have secondary MMUs participate in aging From: James Houghton To: Andrew Morton , Paolo Bonzini Cc: Ankit Agrawal , Axel Rasmussen , Catalin Marinas , David Matlack , David Rientjes , James Houghton , James Morse , Jonathan Corbet , Marc Zyngier , Oliver Upton , Raghavendra Rao Ananta , Ryan Roberts , Sean Christopherson , Shaoqin Huang , Suzuki K Poulose , Wei Xu , Will Deacon , Yu Zhao , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240610_172210_020443_BD1AA639 X-CRM114-Status: GOOD ( 24.67 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Secondary MMUs are currently consulted for access/age information at eviction time, but before then, we don't get accurate age information. That is, pages that are mostly accessed through a secondary MMU (like guest memory, used by KVM) will always just proceed down to the oldest generation, and then at eviction time, if KVM reports the page to be young, the page will be activated/promoted back to the youngest generation. The added feature bit (0x8), if disabled, will make MGLRU behave as if there are no secondary MMUs subscribed to MMU notifiers except at eviction time. Implement aging with the new mmu_notifier_test_clear_young_fast_only() notifier. For architectures that do not support this notifier, this becomes a no-op. For architectures that do implement it, it should be fast enough to make aging worth it. Suggested-by: Yu Zhao Signed-off-by: James Houghton --- Notes: should_look_around() can sometimes use two notifiers now instead of one. This simply comes from restricting myself from not changing mmu_notifier_clear_young() to return more than just "young or not". I could change mmu_notifier_clear_young() (and mmu_notifier_test_young()) to return if it was fast or not. At that point, I could just as well combine all the notifiers into one notifier, like what was in v2 and v3. Documentation/admin-guide/mm/multigen_lru.rst | 6 +- include/linux/mmzone.h | 6 +- mm/rmap.c | 9 +- mm/vmscan.c | 185 ++++++++++++++---- 4 files changed, 164 insertions(+), 42 deletions(-) diff --git a/Documentation/admin-guide/mm/multigen_lru.rst b/Documentation/admin-guide/mm/multigen_lru.rst index 33e068830497..1e578e0c4c0c 100644 --- a/Documentation/admin-guide/mm/multigen_lru.rst +++ b/Documentation/admin-guide/mm/multigen_lru.rst @@ -48,6 +48,10 @@ Values Components verified on x86 varieties other than Intel and AMD. If it is disabled, the multi-gen LRU will suffer a negligible performance degradation. +0x0008 Continuously clear the accessed bit in secondary MMU page + tables instead of waiting until eviction time. This results in + accurate page age information for pages that are mainly used by + a secondary MMU. [yYnN] Apply to all the components above. ====== =============================================================== @@ -56,7 +60,7 @@ E.g., echo y >/sys/kernel/mm/lru_gen/enabled cat /sys/kernel/mm/lru_gen/enabled - 0x0007 + 0x000f echo 5 >/sys/kernel/mm/lru_gen/enabled cat /sys/kernel/mm/lru_gen/enabled 0x0005 diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 8f9c9590a42c..869824ef5f3b 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -400,6 +400,7 @@ enum { LRU_GEN_CORE, LRU_GEN_MM_WALK, LRU_GEN_NONLEAF_YOUNG, + LRU_GEN_SECONDARY_MMU_WALK, NR_LRU_GEN_CAPS }; @@ -557,7 +558,7 @@ struct lru_gen_memcg { void lru_gen_init_pgdat(struct pglist_data *pgdat); void lru_gen_init_lruvec(struct lruvec *lruvec); -void lru_gen_look_around(struct page_vma_mapped_walk *pvmw); +bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw); void lru_gen_init_memcg(struct mem_cgroup *memcg); void lru_gen_exit_memcg(struct mem_cgroup *memcg); @@ -576,8 +577,9 @@ static inline void lru_gen_init_lruvec(struct lruvec *lruvec) { } -static inline void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) +static inline bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw) { + return false; } static inline void lru_gen_init_memcg(struct mem_cgroup *memcg) diff --git a/mm/rmap.c b/mm/rmap.c index e8fc5ecb59b2..24a3ff639919 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -870,13 +870,10 @@ static bool folio_referenced_one(struct folio *folio, continue; } - if (pvmw.pte) { - if (lru_gen_enabled() && - pte_young(ptep_get(pvmw.pte))) { - lru_gen_look_around(&pvmw); + if (lru_gen_enabled() && pvmw.pte) { + if (lru_gen_look_around(&pvmw)) referenced++; - } - + } else if (pvmw.pte) { if (ptep_clear_flush_young_notify(vma, address, pvmw.pte)) referenced++; diff --git a/mm/vmscan.c b/mm/vmscan.c index 2e34de9cd0d4..348f3ffc8d5d 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -56,6 +56,7 @@ #include #include #include +#include #include #include @@ -2579,6 +2580,21 @@ static bool should_clear_pmd_young(void) return arch_has_hw_nonleaf_pmd_young() && get_cap(LRU_GEN_NONLEAF_YOUNG); } +#ifdef CONFIG_HAVE_KVM_YOUNG_FAST_ONLY_NOTIFIER +#include +static bool should_walk_secondary_mmu(void) +{ + return kvm_arch_young_notifier_likely_fast() && + get_cap(LRU_GEN_SECONDARY_MMU_WALK); +} +#else +static bool should_walk_secondary_mmu(void) +{ + return false; +} +#endif + + /****************************************************************************** * shorthand helpers ******************************************************************************/ @@ -3276,7 +3292,8 @@ static bool get_next_vma(unsigned long mask, unsigned long size, struct mm_walk return false; } -static unsigned long get_pte_pfn(pte_t pte, struct vm_area_struct *vma, unsigned long addr) +static unsigned long get_pte_pfn(pte_t pte, struct vm_area_struct *vma, unsigned long addr, + struct pglist_data *pgdat) { unsigned long pfn = pte_pfn(pte); @@ -3291,10 +3308,15 @@ static unsigned long get_pte_pfn(pte_t pte, struct vm_area_struct *vma, unsigned if (WARN_ON_ONCE(!pfn_valid(pfn))) return -1; + /* try to avoid unnecessary memory loads */ + if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat)) + return -1; + return pfn; } -static unsigned long get_pmd_pfn(pmd_t pmd, struct vm_area_struct *vma, unsigned long addr) +static unsigned long get_pmd_pfn(pmd_t pmd, struct vm_area_struct *vma, unsigned long addr, + struct pglist_data *pgdat) { unsigned long pfn = pmd_pfn(pmd); @@ -3309,6 +3331,10 @@ static unsigned long get_pmd_pfn(pmd_t pmd, struct vm_area_struct *vma, unsigned if (WARN_ON_ONCE(!pfn_valid(pfn))) return -1; + /* try to avoid unnecessary memory loads */ + if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat)) + return -1; + return pfn; } @@ -3317,10 +3343,6 @@ static struct folio *get_pfn_folio(unsigned long pfn, struct mem_cgroup *memcg, { struct folio *folio; - /* try to avoid unnecessary memory loads */ - if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat)) - return NULL; - folio = pfn_folio(pfn); if (folio_nid(folio) != pgdat->node_id) return NULL; @@ -3343,6 +3365,43 @@ static bool suitable_to_scan(int total, int young) return young * n >= total; } +static bool lru_gen_notifier_test_clear_young(struct mm_struct *mm, + unsigned long start, + unsigned long end, + bool clear) +{ + return should_walk_secondary_mmu() && + (mmu_notifier_test_clear_young_fast_only( + mm, start, end, clear) & + MMU_NOTIFIER_FAST_YOUNG); +} + +static bool lru_gen_notifier_test_young(struct mm_struct *mm, + unsigned long addr) +{ + return lru_gen_notifier_test_clear_young(mm, addr, addr + PAGE_SIZE, + false); +} + +static bool lru_gen_notifier_clear_young(struct mm_struct *mm, + unsigned long start, + unsigned long end) +{ + return lru_gen_notifier_test_clear_young(mm, start, end, true); +} + +static bool lru_gen_pmdp_test_and_clear_young(struct vm_area_struct *vma, + unsigned long addr, + pmd_t *pmd) +{ + bool young = pmdp_test_and_clear_young(vma, addr, pmd); + + if (lru_gen_notifier_clear_young(vma->vm_mm, addr, addr + PMD_SIZE)) + young = true; + + return young; +} + static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, struct mm_walk *args) { @@ -3357,8 +3416,9 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec); DEFINE_MAX_SEQ(walk->lruvec); int old_gen, new_gen = lru_gen_from_seq(max_seq); + struct mm_struct *mm = args->mm; - pte = pte_offset_map_nolock(args->mm, pmd, start & PMD_MASK, &ptl); + pte = pte_offset_map_nolock(mm, pmd, start & PMD_MASK, &ptl); if (!pte) return false; if (!spin_trylock(ptl)) { @@ -3376,11 +3436,12 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, total++; walk->mm_stats[MM_LEAF_TOTAL]++; - pfn = get_pte_pfn(ptent, args->vma, addr); + pfn = get_pte_pfn(ptent, args->vma, addr, pgdat); if (pfn == -1) continue; - if (!pte_young(ptent)) { + if (!pte_young(ptent) && + !lru_gen_notifier_test_young(mm, addr)) { walk->mm_stats[MM_LEAF_OLD]++; continue; } @@ -3389,8 +3450,9 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, if (!folio) continue; - if (!ptep_test_and_clear_young(args->vma, addr, pte + i)) - VM_WARN_ON_ONCE(true); + lru_gen_notifier_clear_young(mm, addr, addr + PAGE_SIZE); + if (pte_young(ptent)) + ptep_test_and_clear_young(args->vma, addr, pte + i); young++; walk->mm_stats[MM_LEAF_YOUNG]++; @@ -3456,22 +3518,25 @@ static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area /* don't round down the first address */ addr = i ? (*first & PMD_MASK) + i * PMD_SIZE : *first; - pfn = get_pmd_pfn(pmd[i], vma, addr); - if (pfn == -1) - goto next; - - if (!pmd_trans_huge(pmd[i])) { - if (should_clear_pmd_young()) + if (pmd_present(pmd[i]) && !pmd_trans_huge(pmd[i])) { + if (should_clear_pmd_young() && + !should_walk_secondary_mmu()) pmdp_test_and_clear_young(vma, addr, pmd + i); goto next; } + pfn = get_pmd_pfn(pmd[i], vma, addr, pgdat); + if (pfn == -1) + goto next; + folio = get_pfn_folio(pfn, memcg, pgdat, walk->can_swap); if (!folio) goto next; - if (!pmdp_test_and_clear_young(vma, addr, pmd + i)) + if (!lru_gen_pmdp_test_and_clear_young(vma, addr, pmd + i)) { + walk->mm_stats[MM_LEAF_OLD]++; goto next; + } walk->mm_stats[MM_LEAF_YOUNG]++; @@ -3528,19 +3593,18 @@ static void walk_pmd_range(pud_t *pud, unsigned long start, unsigned long end, } if (pmd_trans_huge(val)) { - unsigned long pfn = pmd_pfn(val); struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec); + unsigned long pfn = get_pmd_pfn(val, vma, addr, pgdat); walk->mm_stats[MM_LEAF_TOTAL]++; - if (!pmd_young(val)) { - walk->mm_stats[MM_LEAF_OLD]++; + if (pfn == -1) continue; - } - /* try to avoid unnecessary memory loads */ - if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat)) + if (!pmd_young(val) && !mm_has_notifiers(args->mm)) { + walk->mm_stats[MM_LEAF_OLD]++; continue; + } walk_pmd_range_locked(pud, addr, vma, args, bitmap, &first); continue; @@ -3548,7 +3612,7 @@ static void walk_pmd_range(pud_t *pud, unsigned long start, unsigned long end, walk->mm_stats[MM_NONLEAF_TOTAL]++; - if (should_clear_pmd_young()) { + if (should_clear_pmd_young() && !should_walk_secondary_mmu()) { if (!pmd_young(val)) continue; @@ -3994,6 +4058,47 @@ static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc) * rmap/PT walk feedback ******************************************************************************/ +static bool should_look_around(struct vm_area_struct *vma, unsigned long addr, + pte_t *pte, int *young) +{ + int notifier_result = MMU_NOTIFIER_FAST_FAILED; + bool notifier_was_fast = false; + bool secondary_young = false; + + if (should_walk_secondary_mmu()) { + notifier_result = + mmu_notifier_test_clear_young_fast_only( + vma->vm_mm, addr, addr + PAGE_SIZE, + /*clear=*/true); + } + + if (notifier_result & MMU_NOTIFIER_FAST_FAILED) + secondary_young = mmu_notifier_clear_young(vma->vm_mm, addr, + addr + PAGE_SIZE); + else { + secondary_young = notifier_result & MMU_NOTIFIER_FAST_YOUNG; + notifier_was_fast = true; + } + + /* + * Look around if (1) the PTE is young or (2) the secondary PTE was + * young and the results were gathered fast (so look-around will + * probably be accurate). + */ + if (pte_young(ptep_get(pte))) { + ptep_test_and_clear_young(vma, addr, pte); + *young = true; + return true; + } + + if (secondary_young) { + *young = true; + return notifier_was_fast; + } + + return false; +} + /* * This function exploits spatial locality when shrink_folio_list() walks the * rmap. It scans the adjacent PTEs of a young PTE and promotes hot pages. If @@ -4001,7 +4106,7 @@ static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc) * the PTE table to the Bloom filter. This forms a feedback loop between the * eviction and the aging. */ -void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) +bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw) { int i; unsigned long start; @@ -4019,16 +4124,20 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) struct lru_gen_mm_state *mm_state = get_mm_state(lruvec); DEFINE_MAX_SEQ(lruvec); int old_gen, new_gen = lru_gen_from_seq(max_seq); + struct mm_struct *mm = pvmw->vma->vm_mm; lockdep_assert_held(pvmw->ptl); VM_WARN_ON_ONCE_FOLIO(folio_test_lru(folio), folio); + if (!should_look_around(vma, addr, pte, &young)) + return young; + if (spin_is_contended(pvmw->ptl)) - return; + return young; /* exclude special VMAs containing anon pages from COW */ if (vma->vm_flags & VM_SPECIAL) - return; + return young; /* avoid taking the LRU lock under the PTL when possible */ walk = current->reclaim_state ? current->reclaim_state->mm_walk : NULL; @@ -4036,6 +4145,9 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) start = max(addr & PMD_MASK, vma->vm_start); end = min(addr | ~PMD_MASK, vma->vm_end - 1) + 1; + if (end - start == PAGE_SIZE) + return young; + if (end - start > MIN_LRU_BATCH * PAGE_SIZE) { if (addr - start < MIN_LRU_BATCH * PAGE_SIZE / 2) end = start + MIN_LRU_BATCH * PAGE_SIZE; @@ -4049,7 +4161,7 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) /* folio_update_gen() requires stable folio_memcg() */ if (!mem_cgroup_trylock_pages(memcg)) - return; + return young; arch_enter_lazy_mmu_mode(); @@ -4059,19 +4171,21 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) unsigned long pfn; pte_t ptent = ptep_get(pte + i); - pfn = get_pte_pfn(ptent, vma, addr); + pfn = get_pte_pfn(ptent, vma, addr, pgdat); if (pfn == -1) continue; - if (!pte_young(ptent)) + if (!pte_young(ptent) && + !lru_gen_notifier_test_young(mm, addr)) continue; folio = get_pfn_folio(pfn, memcg, pgdat, can_swap); if (!folio) continue; - if (!ptep_test_and_clear_young(vma, addr, pte + i)) - VM_WARN_ON_ONCE(true); + lru_gen_notifier_clear_young(mm, addr, addr + PAGE_SIZE); + if (pte_young(ptent)) + ptep_test_and_clear_young(vma, addr, pte + i); young++; @@ -4101,6 +4215,8 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) /* feedback from rmap walkers to page table walkers */ if (mm_state && suitable_to_scan(i, young)) update_bloom_filter(mm_state, max_seq, pvmw->pmd); + + return young; } /****************************************************************************** @@ -5137,6 +5253,9 @@ static ssize_t enabled_show(struct kobject *kobj, struct kobj_attribute *attr, c if (should_clear_pmd_young()) caps |= BIT(LRU_GEN_NONLEAF_YOUNG); + if (should_walk_secondary_mmu()) + caps |= BIT(LRU_GEN_SECONDARY_MMU_WALK); + return sysfs_emit(buf, "0x%04x\n", caps); } From patchwork Tue Jun 11 00:21:45 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Houghton X-Patchwork-Id: 13692712 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3851EC27C4F for ; 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Mon, 10 Jun 2024 17:22:06 -0700 (PDT) Date: Tue, 11 Jun 2024 00:21:45 +0000 In-Reply-To: <20240611002145.2078921-1-jthoughton@google.com> Mime-Version: 1.0 References: <20240611002145.2078921-1-jthoughton@google.com> X-Mailer: git-send-email 2.45.2.505.gda0bf45e8d-goog Message-ID: <20240611002145.2078921-10-jthoughton@google.com> Subject: [PATCH v5 9/9] KVM: selftests: Add multi-gen LRU aging to access_tracking_perf_test From: James Houghton To: Andrew Morton , Paolo Bonzini Cc: Ankit Agrawal , Axel Rasmussen , Catalin Marinas , David Matlack , David Rientjes , James Houghton , James Morse , Jonathan Corbet , Marc Zyngier , Oliver Upton , Raghavendra Rao Ananta , Ryan Roberts , Sean Christopherson , Shaoqin Huang , Suzuki K Poulose , Wei Xu , Will Deacon , Yu Zhao , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240610_172211_309522_F794369F X-CRM114-Status: GOOD ( 28.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This test now has two modes of operation: 1. (default) To check how much vCPU performance was affected by access tracking (previously existed, now supports MGLRU aging). 2. (-p) To also benchmark how fast MGLRU can do aging while vCPUs are faulting in memory. Mode (1) also serves as a way to verify that aging is working properly for pages only accessed by KVM. It will fail if one does not have the 0x8 lru_gen feature bit. To support MGLRU, the test creates a memory cgroup, moves itself into it, then uses the lru_gen debugfs output to track memory in that cgroup. The logic to parse the lru_gen debugfs output has been put into selftests/kvm/lib/lru_gen_util.c. Co-developed-by: Axel Rasmussen Signed-off-by: Axel Rasmussen Signed-off-by: James Houghton --- tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/access_tracking_perf_test.c | 365 ++++++++++++++-- .../selftests/kvm/include/lru_gen_util.h | 55 +++ .../testing/selftests/kvm/lib/lru_gen_util.c | 391 ++++++++++++++++++ 4 files changed, 782 insertions(+), 30 deletions(-) create mode 100644 tools/testing/selftests/kvm/include/lru_gen_util.h create mode 100644 tools/testing/selftests/kvm/lib/lru_gen_util.c diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index ac280dcba996..f34b4cdf6524 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -22,6 +22,7 @@ LIBKVM += lib/elf.c LIBKVM += lib/guest_modes.c LIBKVM += lib/io.c LIBKVM += lib/kvm_util.c +LIBKVM += lib/lru_gen_util.c LIBKVM += lib/memstress.c LIBKVM += lib/guest_sprintf.c LIBKVM += lib/rbtree.c diff --git a/tools/testing/selftests/kvm/access_tracking_perf_test.c b/tools/testing/selftests/kvm/access_tracking_perf_test.c index 3c7defd34f56..15be99ff3bdc 100644 --- a/tools/testing/selftests/kvm/access_tracking_perf_test.c +++ b/tools/testing/selftests/kvm/access_tracking_perf_test.c @@ -38,6 +38,7 @@ #include #include #include +#include #include #include #include @@ -47,6 +48,20 @@ #include "memstress.h" #include "guest_modes.h" #include "processor.h" +#include "lru_gen_util.h" + +static const char *TEST_MEMCG_NAME = "access_tracking_perf_test"; +static const int LRU_GEN_ENABLED = 0x1; +static const int LRU_GEN_MM_WALK = 0x2; +static const int LRU_GEN_SECONDARY_MMU_WALK = 0x8; +static const char *CGROUP_PROCS = "cgroup.procs"; +/* + * If using MGLRU, this test assumes a cgroup v2 or cgroup v1 memory hierarchy + * is mounted at cgroup_root. + * + * Can be changed with -r. + */ +static const char *cgroup_root = "/sys/fs/cgroup"; /* Global variable used to synchronize all of the vCPU threads. */ static int iteration; @@ -62,6 +77,9 @@ static enum { /* The iteration that was last completed by each vCPU. */ static int vcpu_last_completed_iteration[KVM_MAX_VCPUS]; +/* The time at which the last iteration was completed */ +static struct timespec vcpu_last_completed_time[KVM_MAX_VCPUS]; + /* Whether to overlap the regions of memory vCPUs access. */ static bool overlap_memory_access; @@ -74,6 +92,12 @@ struct test_params { /* The number of vCPUs to create in the VM. */ int nr_vcpus; + + /* Whether to use lru_gen aging instead of idle page tracking. */ + bool lru_gen; + + /* Whether to test the performance of aging itself. */ + bool benchmark_lru_gen; }; static uint64_t pread_uint64(int fd, const char *filename, uint64_t index) @@ -89,6 +113,50 @@ static uint64_t pread_uint64(int fd, const char *filename, uint64_t index) } +static void write_file_long(const char *path, long v) +{ + FILE *f; + + f = fopen(path, "w"); + TEST_ASSERT(f, "fopen(%s) failed", path); + TEST_ASSERT(fprintf(f, "%ld\n", v) > 0, + "fprintf to %s failed", path); + TEST_ASSERT(!fclose(f), "fclose(%s) failed", path); +} + +static char *path_join(const char *parent, const char *child) +{ + char *out = NULL; + + return asprintf(&out, "%s/%s", parent, child) >= 0 ? out : NULL; +} + +static char *memcg_path(const char *memcg) +{ + return path_join(cgroup_root, memcg); +} + +static char *memcg_file_path(const char *memcg, const char *file) +{ + char *mp = memcg_path(memcg); + char *fp; + + if (!mp) + return NULL; + fp = path_join(mp, file); + free(mp); + return fp; +} + +static void move_to_memcg(const char *memcg, pid_t pid) +{ + char *procs = memcg_file_path(memcg, CGROUP_PROCS); + + TEST_ASSERT(procs, "Failed to construct cgroup.procs path"); + write_file_long(procs, pid); + free(procs); +} + #define PAGEMAP_PRESENT (1ULL << 63) #define PAGEMAP_PFN_MASK ((1ULL << 55) - 1) @@ -242,6 +310,8 @@ static void vcpu_thread_main(struct memstress_vcpu_args *vcpu_args) }; vcpu_last_completed_iteration[vcpu_idx] = current_iteration; + clock_gettime(CLOCK_MONOTONIC, + &vcpu_last_completed_time[vcpu_idx]); } } @@ -253,38 +323,68 @@ static void spin_wait_for_vcpu(int vcpu_idx, int target_iteration) } } +static bool all_vcpus_done(int target_iteration, int nr_vcpus) +{ + for (int i = 0; i < nr_vcpus; ++i) + if (READ_ONCE(vcpu_last_completed_iteration[i]) != + target_iteration) + return false; + + return true; +} + /* The type of memory accesses to perform in the VM. */ enum access_type { ACCESS_READ, ACCESS_WRITE, }; -static void run_iteration(struct kvm_vm *vm, int nr_vcpus, const char *description) +static void run_iteration(struct kvm_vm *vm, int nr_vcpus, const char *description, + bool wait) { - struct timespec ts_start; - struct timespec ts_elapsed; int next_iteration, i; /* Kick off the vCPUs by incrementing iteration. */ next_iteration = ++iteration; - clock_gettime(CLOCK_MONOTONIC, &ts_start); - /* Wait for all vCPUs to finish the iteration. */ - for (i = 0; i < nr_vcpus; i++) - spin_wait_for_vcpu(i, next_iteration); + if (wait) { + struct timespec ts_start; + struct timespec ts_elapsed; + + clock_gettime(CLOCK_MONOTONIC, &ts_start); - ts_elapsed = timespec_elapsed(ts_start); - pr_info("%-30s: %ld.%09lds\n", - description, ts_elapsed.tv_sec, ts_elapsed.tv_nsec); + for (i = 0; i < nr_vcpus; i++) + spin_wait_for_vcpu(i, next_iteration); + + ts_elapsed = timespec_elapsed(ts_start); + + pr_info("%-30s: %ld.%09lds\n", + description, ts_elapsed.tv_sec, ts_elapsed.tv_nsec); + } else + pr_info("%-30s\n", description); } -static void access_memory(struct kvm_vm *vm, int nr_vcpus, - enum access_type access, const char *description) +static void _access_memory(struct kvm_vm *vm, int nr_vcpus, + enum access_type access, const char *description, + bool wait) { memstress_set_write_percent(vm, (access == ACCESS_READ) ? 0 : 100); iteration_work = ITERATION_ACCESS_MEMORY; - run_iteration(vm, nr_vcpus, description); + run_iteration(vm, nr_vcpus, description, wait); +} + +static void access_memory(struct kvm_vm *vm, int nr_vcpus, + enum access_type access, const char *description) +{ + return _access_memory(vm, nr_vcpus, access, description, true); +} + +static void access_memory_async(struct kvm_vm *vm, int nr_vcpus, + enum access_type access, + const char *description) +{ + return _access_memory(vm, nr_vcpus, access, description, false); } static void mark_memory_idle(struct kvm_vm *vm, int nr_vcpus) @@ -297,19 +397,111 @@ static void mark_memory_idle(struct kvm_vm *vm, int nr_vcpus) */ pr_debug("Marking VM memory idle (slow)...\n"); iteration_work = ITERATION_MARK_IDLE; - run_iteration(vm, nr_vcpus, "Mark memory idle"); + run_iteration(vm, nr_vcpus, "Mark memory idle", true); } -static void run_test(enum vm_guest_mode mode, void *arg) +static void create_memcg(const char *memcg) +{ + const char *full_memcg_path = memcg_path(memcg); + int ret; + + TEST_ASSERT(full_memcg_path, "Failed to construct full memcg path"); +retry: + ret = mkdir(full_memcg_path, 0755); + if (ret && errno == EEXIST) { + TEST_ASSERT(!rmdir(full_memcg_path), + "Found existing memcg at %s, but rmdir failed", + full_memcg_path); + goto retry; + } + TEST_ASSERT(!ret, "Creating the memcg failed: mkdir(%s) failed", + full_memcg_path); + + pr_info("Created memcg at %s\n", full_memcg_path); +} + +/* + * Test lru_gen aging speed while vCPUs are faulting memory in. + * + * This test will run lru_gen aging until the vCPUs have finished all of + * the faulting work, reporting: + * - vcpu wall time (wall time for slowest vCPU) + * - average aging pass duration + * - total number of aging passes + * - total time spent aging + * + * This test produces the most useful results when the vcpu wall time and the + * total time spent aging are similar (i.e., we want to avoid timing aging + * while the vCPUs aren't doing any work). + */ +static void run_benchmark(enum vm_guest_mode mode, struct kvm_vm *vm, + struct test_params *params) { - struct test_params *params = arg; - struct kvm_vm *vm; int nr_vcpus = params->nr_vcpus; + struct memcg_stats stats; + struct timespec ts_start, ts_max, ts_vcpus_elapsed, + ts_aging_elapsed, ts_aging_elapsed_avg; + int num_passes = 0; - vm = memstress_create_vm(mode, nr_vcpus, params->vcpu_memory_bytes, 1, - params->backing_src, !overlap_memory_access); + printf("Running lru_gen benchmark...\n"); - memstress_start_vcpu_threads(nr_vcpus, vcpu_thread_main); + clock_gettime(CLOCK_MONOTONIC, &ts_start); + access_memory_async(vm, nr_vcpus, ACCESS_WRITE, + "Populating memory (async)"); + while (!all_vcpus_done(iteration, nr_vcpus)) { + lru_gen_do_aging_quiet(&stats, TEST_MEMCG_NAME); + ++num_passes; + } + + ts_aging_elapsed = timespec_elapsed(ts_start); + ts_aging_elapsed_avg = timespec_div(ts_aging_elapsed, num_passes); + + /* Find out when the slowest vCPU finished. */ + ts_max = ts_start; + for (int i = 0; i < nr_vcpus; ++i) { + struct timespec *vcpu_ts = &vcpu_last_completed_time[i]; + + if (ts_max.tv_sec < vcpu_ts->tv_sec || + (ts_max.tv_sec == vcpu_ts->tv_sec && + ts_max.tv_nsec < vcpu_ts->tv_nsec)) + ts_max = *vcpu_ts; + } + + ts_vcpus_elapsed = timespec_sub(ts_max, ts_start); + + pr_info("%-30s: %ld.%09lds\n", "vcpu wall time", + ts_vcpus_elapsed.tv_sec, ts_vcpus_elapsed.tv_nsec); + + pr_info("%-30s: %ld.%09lds, (passes:%d, total:%ld.%09lds)\n", + "lru_gen avg pass duration", + ts_aging_elapsed_avg.tv_sec, + ts_aging_elapsed_avg.tv_nsec, + num_passes, + ts_aging_elapsed.tv_sec, + ts_aging_elapsed.tv_nsec); +} + +/* + * Test how much access tracking affects vCPU performance. + * + * Supports two modes of access tracking: + * - idle page tracking + * - lru_gen aging + * + * When using lru_gen, this test additionally verifies that the pages are in + * fact getting younger and older, otherwise the performance data would be + * invalid. + * + * The forced lru_gen aging can race with aging that occurs naturally. + */ +static void run_test(enum vm_guest_mode mode, struct kvm_vm *vm, + struct test_params *params) +{ + int nr_vcpus = params->nr_vcpus; + bool lru_gen = params->lru_gen; + struct memcg_stats stats; + long total_pages = nr_vcpus * params->vcpu_memory_bytes / getpagesize(); + int found_gens[5]; pr_info("\n"); access_memory(vm, nr_vcpus, ACCESS_WRITE, "Populating memory"); @@ -319,11 +511,83 @@ static void run_test(enum vm_guest_mode mode, void *arg) access_memory(vm, nr_vcpus, ACCESS_READ, "Reading from populated memory"); /* Repeat on memory that has been marked as idle. */ - mark_memory_idle(vm, nr_vcpus); + if (lru_gen) { + /* Do an initial page table scan */ + lru_gen_do_aging(&stats, TEST_MEMCG_NAME); + TEST_ASSERT(sum_memcg_stats(&stats) >= total_pages, + "Not all pages tracked in lru_gen stats.\n" + "Is lru_gen enabled? Did the memcg get created properly?"); + + /* Find the generation we're currently in (probably youngest) */ + found_gens[0] = lru_gen_find_generation(&stats, total_pages); + + /* Do an aging pass now */ + lru_gen_do_aging(&stats, TEST_MEMCG_NAME); + + /* Same generation, but a newer generation has been made */ + found_gens[1] = lru_gen_find_generation(&stats, total_pages); + TEST_ASSERT(found_gens[1] == found_gens[0], + "unexpected gen change: %d vs. %d", + found_gens[1], found_gens[0]); + } else + mark_memory_idle(vm, nr_vcpus); + access_memory(vm, nr_vcpus, ACCESS_WRITE, "Writing to idle memory"); - mark_memory_idle(vm, nr_vcpus); + + if (lru_gen) { + /* Scan the page tables again */ + lru_gen_do_aging(&stats, TEST_MEMCG_NAME); + + /* The pages should now be young again, so in a newer generation */ + found_gens[2] = lru_gen_find_generation(&stats, total_pages); + TEST_ASSERT(found_gens[2] > found_gens[1], + "pages did not get younger"); + + /* Do another aging pass */ + lru_gen_do_aging(&stats, TEST_MEMCG_NAME); + + /* Same generation; new generation has been made */ + found_gens[3] = lru_gen_find_generation(&stats, total_pages); + TEST_ASSERT(found_gens[3] == found_gens[2], + "unexpected gen change: %d vs. %d", + found_gens[3], found_gens[2]); + } else + mark_memory_idle(vm, nr_vcpus); + access_memory(vm, nr_vcpus, ACCESS_READ, "Reading from idle memory"); + if (lru_gen) { + /* Scan the pages tables again */ + lru_gen_do_aging(&stats, TEST_MEMCG_NAME); + + /* The pages should now be young again, so in a newer generation */ + found_gens[4] = lru_gen_find_generation(&stats, total_pages); + TEST_ASSERT(found_gens[4] > found_gens[3], + "pages did not get younger"); + } +} + +static void setup_vm_and_run(enum vm_guest_mode mode, void *arg) +{ + struct test_params *params = arg; + int nr_vcpus = params->nr_vcpus; + struct kvm_vm *vm; + + if (params->lru_gen) { + create_memcg(TEST_MEMCG_NAME); + move_to_memcg(TEST_MEMCG_NAME, getpid()); + } + + vm = memstress_create_vm(mode, nr_vcpus, params->vcpu_memory_bytes, 1, + params->backing_src, !overlap_memory_access); + + memstress_start_vcpu_threads(nr_vcpus, vcpu_thread_main); + + if (params->benchmark_lru_gen) + run_benchmark(mode, vm, params); + else + run_test(mode, vm, params); + memstress_join_vcpu_threads(nr_vcpus); memstress_destroy_vm(vm); } @@ -331,8 +595,8 @@ static void run_test(enum vm_guest_mode mode, void *arg) static void help(char *name) { puts(""); - printf("usage: %s [-h] [-m mode] [-b vcpu_bytes] [-v vcpus] [-o] [-s mem_type]\n", - name); + printf("usage: %s [-h] [-m mode] [-b vcpu_bytes] [-v vcpus] [-o]" + " [-s mem_type] [-l] [-r memcg_root]\n", name); puts(""); printf(" -h: Display this help message."); guest_modes_help(); @@ -342,6 +606,9 @@ static void help(char *name) printf(" -v: specify the number of vCPUs to run.\n"); printf(" -o: Overlap guest memory accesses instead of partitioning\n" " them into a separate region of memory for each vCPU.\n"); + printf(" -l: Use MGLRU aging instead of idle page tracking\n"); + printf(" -p: Benchmark MGLRU aging while faulting memory in\n"); + printf(" -r: The memory cgroup hierarchy root to use (when -l is given)\n"); backing_src_help("-s"); puts(""); exit(0); @@ -353,13 +620,15 @@ int main(int argc, char *argv[]) .backing_src = DEFAULT_VM_MEM_SRC, .vcpu_memory_bytes = DEFAULT_PER_VCPU_MEM_SIZE, .nr_vcpus = 1, + .lru_gen = false, + .benchmark_lru_gen = false, }; int page_idle_fd; int opt; guest_modes_append_default(); - while ((opt = getopt(argc, argv, "hm:b:v:os:")) != -1) { + while ((opt = getopt(argc, argv, "hm:b:v:os:lr:p")) != -1) { switch (opt) { case 'm': guest_modes_cmdline(optarg); @@ -376,6 +645,15 @@ int main(int argc, char *argv[]) case 's': params.backing_src = parse_backing_src_type(optarg); break; + case 'l': + params.lru_gen = true; + break; + case 'p': + params.benchmark_lru_gen = true; + break; + case 'r': + cgroup_root = strdup(optarg); + break; case 'h': default: help(argv[0]); @@ -383,12 +661,39 @@ int main(int argc, char *argv[]) } } - page_idle_fd = open("/sys/kernel/mm/page_idle/bitmap", O_RDWR); - __TEST_REQUIRE(page_idle_fd >= 0, - "CONFIG_IDLE_PAGE_TRACKING is not enabled"); - close(page_idle_fd); + if (!params.lru_gen) { + page_idle_fd = open("/sys/kernel/mm/page_idle/bitmap", O_RDWR); + __TEST_REQUIRE(page_idle_fd >= 0, + "CONFIG_IDLE_PAGE_TRACKING is not enabled"); + close(page_idle_fd); + } else { + int lru_gen_fd, lru_gen_debug_fd; + long mglru_features; + char mglru_feature_str[8] = {}; + + lru_gen_fd = open("/sys/kernel/mm/lru_gen/enabled", O_RDONLY); + __TEST_REQUIRE(lru_gen_fd >= 0, + "CONFIG_LRU_GEN is not enabled"); + TEST_ASSERT(read(lru_gen_fd, &mglru_feature_str, 7) > 0, + "couldn't read lru_gen features"); + mglru_features = strtol(mglru_feature_str, NULL, 16); + __TEST_REQUIRE(mglru_features & LRU_GEN_ENABLED, + "lru_gen is not enabled"); + __TEST_REQUIRE(mglru_features & LRU_GEN_MM_WALK, + "lru_gen does not support MM_WALK"); + __TEST_REQUIRE(mglru_features & LRU_GEN_SECONDARY_MMU_WALK, + "lru_gen does not support SECONDARY_MMU_WALK"); + + lru_gen_debug_fd = open(DEBUGFS_LRU_GEN, O_RDWR); + __TEST_REQUIRE(lru_gen_debug_fd >= 0, + "Cannot access %s", DEBUGFS_LRU_GEN); + close(lru_gen_debug_fd); + } + + TEST_ASSERT(!params.benchmark_lru_gen || params.lru_gen, + "-p specified without -l"); - for_each_guest_mode(run_test, ¶ms); + for_each_guest_mode(setup_vm_and_run, ¶ms); return 0; } diff --git a/tools/testing/selftests/kvm/include/lru_gen_util.h b/tools/testing/selftests/kvm/include/lru_gen_util.h new file mode 100644 index 000000000000..4eef8085a3cb --- /dev/null +++ b/tools/testing/selftests/kvm/include/lru_gen_util.h @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Tools for integrating with lru_gen, like parsing the lru_gen debugfs output. + * + * Copyright (C) 2024, Google LLC. + */ +#ifndef SELFTEST_KVM_LRU_GEN_UTIL_H +#define SELFTEST_KVM_LRU_GEN_UTIL_H + +#include +#include +#include + +#include "test_util.h" + +#define MAX_NR_GENS 16 /* MAX_NR_GENS in include/linux/mmzone.h */ +#define MAX_NR_NODES 4 /* Maximum number of nodes we support */ + +static const char *DEBUGFS_LRU_GEN = "/sys/kernel/debug/lru_gen"; + +struct generation_stats { + int gen; + long age_ms; + long nr_anon; + long nr_file; +}; + +struct node_stats { + int node; + int nr_gens; /* Number of populated gens entries. */ + struct generation_stats gens[MAX_NR_GENS]; +}; + +struct memcg_stats { + unsigned long memcg_id; + int nr_nodes; /* Number of populated nodes entries. */ + struct node_stats nodes[MAX_NR_NODES]; +}; + +void print_memcg_stats(const struct memcg_stats *stats, const char *name); + +void read_memcg_stats(struct memcg_stats *stats, const char *memcg); + +void read_print_memcg_stats(struct memcg_stats *stats, const char *memcg); + +long sum_memcg_stats(const struct memcg_stats *stats); + +void lru_gen_do_aging(struct memcg_stats *stats, const char *memcg); + +void lru_gen_do_aging_quiet(struct memcg_stats *stats, const char *memcg); + +int lru_gen_find_generation(const struct memcg_stats *stats, + unsigned long total_pages); + +#endif /* SELFTEST_KVM_LRU_GEN_UTIL_H */ diff --git a/tools/testing/selftests/kvm/lib/lru_gen_util.c b/tools/testing/selftests/kvm/lib/lru_gen_util.c new file mode 100644 index 000000000000..3c02a635a9f7 --- /dev/null +++ b/tools/testing/selftests/kvm/lib/lru_gen_util.c @@ -0,0 +1,391 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2024, Google LLC. + */ + +#include + +#include "lru_gen_util.h" + +/* + * Tracks state while we parse memcg lru_gen stats. The file we're parsing is + * structured like this (some extra whitespace elided): + * + * memcg (id) (path) + * node (id) + * (gen_nr) (age_in_ms) (nr_anon_pages) (nr_file_pages) + */ +struct memcg_stats_parse_context { + bool consumed; /* Whether or not this line was consumed */ + /* Next parse handler to invoke */ + void (*next_handler)(struct memcg_stats *, + struct memcg_stats_parse_context *, char *); + int current_node_idx; /* Current index in nodes array */ + const char *name; /* The name of the memcg we're looking for */ +}; + +static void memcg_stats_handle_searching(struct memcg_stats *stats, + struct memcg_stats_parse_context *ctx, + char *line); +static void memcg_stats_handle_in_memcg(struct memcg_stats *stats, + struct memcg_stats_parse_context *ctx, + char *line); +static void memcg_stats_handle_in_node(struct memcg_stats *stats, + struct memcg_stats_parse_context *ctx, + char *line); + +struct split_iterator { + char *str; + char *save; +}; + +static char *split_next(struct split_iterator *it) +{ + char *ret = strtok_r(it->str, " \t\n\r", &it->save); + + it->str = NULL; + return ret; +} + +static void memcg_stats_handle_searching(struct memcg_stats *stats, + struct memcg_stats_parse_context *ctx, + char *line) +{ + struct split_iterator it = { .str = line }; + char *prefix = split_next(&it); + char *memcg_id = split_next(&it); + char *memcg_name = split_next(&it); + char *end; + + ctx->consumed = true; + + if (!prefix || strcmp("memcg", prefix)) + return; /* Not a memcg line (maybe empty), skip */ + + TEST_ASSERT(memcg_id && memcg_name, + "malformed memcg line; no memcg id or memcg_name"); + + if (strcmp(memcg_name + 1, ctx->name)) + return; /* Wrong memcg, skip */ + + /* Found it! */ + + stats->memcg_id = strtoul(memcg_id, &end, 10); + TEST_ASSERT(*end == '\0', "malformed memcg id '%s'", memcg_id); + if (!stats->memcg_id) + return; /* Removed memcg? */ + + ctx->next_handler = memcg_stats_handle_in_memcg; +} + +static void memcg_stats_handle_in_memcg(struct memcg_stats *stats, + struct memcg_stats_parse_context *ctx, + char *line) +{ + struct split_iterator it = { .str = line }; + char *prefix = split_next(&it); + char *id = split_next(&it); + long found_node_id; + char *end; + + ctx->consumed = true; + ctx->current_node_idx = -1; + + if (!prefix) + return; /* Skip empty lines */ + + if (!strcmp("memcg", prefix)) { + /* Memcg done, found next one; stop. */ + ctx->next_handler = NULL; + return; + } else if (strcmp("node", prefix)) + TEST_ASSERT(false, "found malformed line after 'memcg ...'," + "token: '%s'", prefix); + + /* At this point we know we have a node line. Parse the ID. */ + + TEST_ASSERT(id, "malformed node line; no node id"); + + found_node_id = strtol(id, &end, 10); + TEST_ASSERT(*end == '\0', "malformed node id '%s'", id); + + ctx->current_node_idx = stats->nr_nodes++; + TEST_ASSERT(ctx->current_node_idx < MAX_NR_NODES, + "memcg has stats for too many nodes, max is %d", + MAX_NR_NODES); + stats->nodes[ctx->current_node_idx].node = found_node_id; + + ctx->next_handler = memcg_stats_handle_in_node; +} + +static void memcg_stats_handle_in_node(struct memcg_stats *stats, + struct memcg_stats_parse_context *ctx, + char *line) +{ + /* Have to copy since we might not consume */ + char *my_line = strdup(line); + struct split_iterator it = { .str = my_line }; + char *gen, *age, *nr_anon, *nr_file; + struct node_stats *node_stats; + struct generation_stats *gen_stats; + char *end; + + TEST_ASSERT(it.str, "failed to copy input line"); + + gen = split_next(&it); + + /* Skip empty lines */ + if (!gen) + goto out_consume; /* Skip empty lines */ + + if (!strcmp("memcg", gen) || !strcmp("node", gen)) { + /* + * Reached next memcg or node section. Don't consume, let the + * other handler deal with this. + */ + ctx->next_handler = memcg_stats_handle_in_memcg; + goto out; + } + + node_stats = &stats->nodes[ctx->current_node_idx]; + TEST_ASSERT(node_stats->nr_gens < MAX_NR_GENS, + "found too many generation lines; max is %d", + MAX_NR_GENS); + gen_stats = &node_stats->gens[node_stats->nr_gens++]; + + age = split_next(&it); + nr_anon = split_next(&it); + nr_file = split_next(&it); + + TEST_ASSERT(age && nr_anon && nr_file, + "malformed generation line; not enough tokens"); + + gen_stats->gen = (int)strtol(gen, &end, 10); + TEST_ASSERT(*end == '\0', "malformed generation number '%s'", gen); + + gen_stats->age_ms = strtol(age, &end, 10); + TEST_ASSERT(*end == '\0', "malformed generation age '%s'", age); + + gen_stats->nr_anon = strtol(nr_anon, &end, 10); + TEST_ASSERT(*end == '\0', "malformed anonymous page count '%s'", + nr_anon); + + gen_stats->nr_file = strtol(nr_file, &end, 10); + TEST_ASSERT(*end == '\0', "malformed file page count '%s'", nr_file); + +out_consume: + ctx->consumed = true; +out: + free(my_line); +} + +/* Pretty-print lru_gen @stats. */ +void print_memcg_stats(const struct memcg_stats *stats, const char *name) +{ + int node, gen; + + fprintf(stderr, "stats for memcg %s (id %lu):\n", + name, stats->memcg_id); + for (node = 0; node < stats->nr_nodes; ++node) { + fprintf(stderr, "\tnode %d\n", stats->nodes[node].node); + for (gen = 0; gen < stats->nodes[node].nr_gens; ++gen) { + const struct generation_stats *gstats = + &stats->nodes[node].gens[gen]; + + fprintf(stderr, + "\t\tgen %d\tage_ms %ld" + "\tnr_anon %ld\tnr_file %ld\n", + gstats->gen, gstats->age_ms, gstats->nr_anon, + gstats->nr_file); + } + } +} + +/* Re-read lru_gen debugfs information for @memcg into @stats. */ +void read_memcg_stats(struct memcg_stats *stats, const char *memcg) +{ + FILE *f; + ssize_t read = 0; + char *line = NULL; + size_t bufsz; + struct memcg_stats_parse_context ctx = { + .next_handler = memcg_stats_handle_searching, + .name = memcg, + }; + + memset(stats, 0, sizeof(struct memcg_stats)); + + f = fopen(DEBUGFS_LRU_GEN, "r"); + TEST_ASSERT(f, "fopen(%s) failed", DEBUGFS_LRU_GEN); + + while (ctx.next_handler && (read = getline(&line, &bufsz, f)) > 0) { + ctx.consumed = false; + + do { + ctx.next_handler(stats, &ctx, line); + if (!ctx.next_handler) + break; + } while (!ctx.consumed); + } + + if (read < 0 && !feof(f)) + TEST_ASSERT(false, "getline(%s) failed", DEBUGFS_LRU_GEN); + + TEST_ASSERT(stats->memcg_id > 0, "Couldn't find memcg: %s\n" + "Did the memcg get created in the proper mount?", + memcg); + if (line) + free(line); + TEST_ASSERT(!fclose(f), "fclose(%s) failed", DEBUGFS_LRU_GEN); +} + +/* + * Find all pages tracked by lru_gen for this memcg in generation @target_gen. + * + * If @target_gen is negative, look for all generations. + */ +static long sum_memcg_stats_for_gen(int target_gen, + const struct memcg_stats *stats) +{ + int node, gen; + long total_nr = 0; + + for (node = 0; node < stats->nr_nodes; ++node) { + const struct node_stats *node_stats = &stats->nodes[node]; + + for (gen = 0; gen < node_stats->nr_gens; ++gen) { + const struct generation_stats *gen_stats = + &node_stats->gens[gen]; + + if (target_gen >= 0 && gen_stats->gen != target_gen) + continue; + + total_nr += gen_stats->nr_anon + gen_stats->nr_file; + } + } + + return total_nr; +} + +/* Find all pages tracked by lru_gen for this memcg. */ +long sum_memcg_stats(const struct memcg_stats *stats) +{ + return sum_memcg_stats_for_gen(-1, stats); +} + +/* Read the memcg stats and optionally print if this is a debug build. */ +void read_print_memcg_stats(struct memcg_stats *stats, const char *memcg) +{ + read_memcg_stats(stats, memcg); +#ifdef DEBUG + print_memcg_stats(stats, memcg); +#endif +} + +/* + * If lru_gen aging should force page table scanning. + * + * If you want to set this to false, you will need to do eviction + * before doing extra aging passes. + */ +static const bool force_scan = true; + +static void run_aging_impl(unsigned long memcg_id, int node_id, int max_gen) +{ + FILE *f = fopen(DEBUGFS_LRU_GEN, "w"); + char *command; + size_t sz; + + TEST_ASSERT(f, "fopen(%s) failed", DEBUGFS_LRU_GEN); + sz = asprintf(&command, "+ %lu %d %d 1 %d\n", + memcg_id, node_id, max_gen, force_scan); + TEST_ASSERT(sz > 0, "creating aging command failed"); + + pr_debug("Running aging command: %s", command); + if (fwrite(command, sizeof(char), sz, f) < sz) { + TEST_ASSERT(false, "writing aging command %s to %s failed", + command, DEBUGFS_LRU_GEN); + } + + TEST_ASSERT(!fclose(f), "fclose(%s) failed", DEBUGFS_LRU_GEN); +} + +static void _lru_gen_do_aging(struct memcg_stats *stats, const char *memcg, + bool verbose) +{ + int node, gen; + struct timespec ts_start; + struct timespec ts_elapsed; + + pr_debug("lru_gen: invoking aging...\n"); + + /* Must read memcg stats to construct the proper aging command. */ + read_print_memcg_stats(stats, memcg); + + if (verbose) + clock_gettime(CLOCK_MONOTONIC, &ts_start); + + for (node = 0; node < stats->nr_nodes; ++node) { + int max_gen = 0; + + for (gen = 0; gen < stats->nodes[node].nr_gens; ++gen) { + int this_gen = stats->nodes[node].gens[gen].gen; + + max_gen = max_gen > this_gen ? max_gen : this_gen; + } + + run_aging_impl(stats->memcg_id, stats->nodes[node].node, + max_gen); + } + + if (verbose) { + ts_elapsed = timespec_elapsed(ts_start); + pr_info("%-30s: %ld.%09lds\n", "lru_gen: Aging", + ts_elapsed.tv_sec, ts_elapsed.tv_nsec); + } + + /* Re-read so callers get updated information */ + read_print_memcg_stats(stats, memcg); +} + +/* Do aging, and print how long it took. */ +void lru_gen_do_aging(struct memcg_stats *stats, const char *memcg) +{ + return _lru_gen_do_aging(stats, memcg, true); +} + +/* Do aging, don't print anything. */ +void lru_gen_do_aging_quiet(struct memcg_stats *stats, const char *memcg) +{ + return _lru_gen_do_aging(stats, memcg, false); +} + +/* + * Find which generation contains more than half of @total_pages, assuming that + * such a generation exists. + */ +int lru_gen_find_generation(const struct memcg_stats *stats, + unsigned long total_pages) +{ + int node, gen, gen_idx, min_gen = INT_MAX, max_gen = -1; + + for (node = 0; node < stats->nr_nodes; ++node) + for (gen_idx = 0; gen_idx < stats->nodes[node].nr_gens; + ++gen_idx) { + gen = stats->nodes[node].gens[gen_idx].gen; + max_gen = gen > max_gen ? gen : max_gen; + min_gen = gen < min_gen ? gen : min_gen; + } + + for (gen = min_gen; gen < max_gen; ++gen) + /* See if the most pages are in this generation. */ + if (sum_memcg_stats_for_gen(gen, stats) > + total_pages / 2) + return gen; + + TEST_ASSERT(false, "No generation includes majority of %lu pages.", + total_pages); + + /* unreachable, but make the compiler happy */ + return -1; +}