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[99.241.198.116]) by smtp.gmail.com with ESMTPSA id n4-20020a056e02140400b002d522958fb4sm1726538ilo.2.2022.06.16.18.41.51 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 16 Jun 2022 18:41:51 -0700 (PDT) From: Peter Xu To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "Dr . David Alan Gilbert" , Linux MM Mailing List , Sean Christopherson , Paolo Bonzini , Andrea Arcangeli , Andrew Morton , peterx@redhat.com Subject: [PATCH RFC 1/4] mm/gup: Add FOLL_INTERRUPTIBLE Date: Thu, 16 Jun 2022 21:41:44 -0400 Message-Id: <20220617014147.7299-2-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220617014147.7299-1-peterx@redhat.com> References: <20220617014147.7299-1-peterx@redhat.com> MIME-Version: 1.0 Content-type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org We have had FAULT_FLAG_INTERRUPTIBLE but it was never applied to GUPs. One issue with it is that not all GUP paths are able to handle signal delivers besides SIGKILL. That's not ideal for the GUP users who are actually able to handle these cases, like KVM. KVM uses GUP extensively on faulting guest pages, during which we've got existing infrastructures to retry a page fault at a later time. Allowing the GUP to be interrupted by generic signals can make KVM related threads to be more responsive. For examples: (1) SIGUSR1: which QEMU/KVM uses to deliver an inter-process IPI, e.g. when the admin issues a vm_stop QMP command, SIGUSR1 can be generated to kick the vcpus out of kernel context immediately, (2) SIGINT: which can be used with interactive hypervisor users to stop a virtual machine with Ctrl-C without any delays/hangs, (3) SIGTRAP: which grants GDB capability even during page faults that are stuck for a long time. Normally hypervisor will be able to receive these signals properly, but not if we're stuck in a GUP for a long time for whatever reason. It happens easily with a stucked postcopy migration when e.g. a network temp failure happens, then some vcpu threads can hang death waiting for the pages. With the new FOLL_INTERRUPTIBLE, we can allow GUP users like KVM to selectively enable the ability to trap these signals. Signed-off-by: Peter Xu --- include/linux/mm.h | 1 + mm/gup.c | 33 +++++++++++++++++++++++++++++---- 2 files changed, 30 insertions(+), 4 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index bc8f326be0ce..ebdf8a6b86c1 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2941,6 +2941,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, #define FOLL_SPLIT_PMD 0x20000 /* split huge pmd before returning */ #define FOLL_PIN 0x40000 /* pages must be released via unpin_user_page */ #define FOLL_FAST_ONLY 0x80000 /* gup_fast: prevent fall-back to slow gup */ +#define FOLL_INTERRUPTIBLE 0x100000 /* allow interrupts from generic signals */ /* * FOLL_PIN and FOLL_LONGTERM may be used in various combinations with each diff --git a/mm/gup.c b/mm/gup.c index 551264407624..ad74b137d363 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -933,8 +933,17 @@ static int faultin_page(struct vm_area_struct *vma, fault_flags |= FAULT_FLAG_WRITE; if (*flags & FOLL_REMOTE) fault_flags |= FAULT_FLAG_REMOTE; - if (locked) + if (locked) { fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; + /* + * We should only grant FAULT_FLAG_INTERRUPTIBLE when we're + * (at least) killable. It also mostly means we're not + * with NOWAIT. Otherwise ignore FOLL_INTERRUPTIBLE since + * it won't make a lot of sense to be used alone. + */ + if (*flags & FOLL_INTERRUPTIBLE) + fault_flags |= FAULT_FLAG_INTERRUPTIBLE; + } if (*flags & FOLL_NOWAIT) fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT; if (*flags & FOLL_TRIED) { @@ -1322,6 +1331,22 @@ int fixup_user_fault(struct mm_struct *mm, } EXPORT_SYMBOL_GPL(fixup_user_fault); +/* + * GUP always responds to fatal signals. When FOLL_INTERRUPTIBLE is + * specified, it'll also respond to generic signals. The caller of GUP + * that has FOLL_INTERRUPTIBLE should take care of the GUP interruption. + */ +static bool gup_signal_pending(unsigned int flags) +{ + if (fatal_signal_pending(current)) + return true; + + if (!(flags & FOLL_INTERRUPTIBLE)) + return false; + + return signal_pending(current); +} + /* * Please note that this function, unlike __get_user_pages will not * return 0 for nr_pages > 0 without FOLL_NOWAIT @@ -1403,11 +1428,11 @@ static __always_inline long __get_user_pages_locked(struct mm_struct *mm, * Repeat on the address that fired VM_FAULT_RETRY * with both FAULT_FLAG_ALLOW_RETRY and * FAULT_FLAG_TRIED. Note that GUP can be interrupted - * by fatal signals, so we need to check it before we + * by fatal signals of even common signals, depending on + * the caller's request. So we need to check it before we * start trying again otherwise it can loop forever. */ - - if (fatal_signal_pending(current)) { + if (gup_signal_pending(flags)) { if (!pages_done) pages_done = -EINTR; break; From patchwork Fri Jun 17 01:41:45 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Xu X-Patchwork-Id: 12885029 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F75FCCA47F for ; Fri, 17 Jun 2022 01:42:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379390AbiFQBmH (ORCPT ); Thu, 16 Jun 2022 21:42:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1379591AbiFQBl7 (ORCPT ); Thu, 16 Jun 2022 21:41:59 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 92FB963BC9 for ; Thu, 16 Jun 2022 18:41:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655430117; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=bR8MuwpznI9qRUj89FotcZKYXyQ5fO5vJmhSv17cXWQ=; b=QhBJ0fKocsQPKEJrUyBaWQcOT0lkiSgEqLIsc5NUQ0667G45F41zRW9PuH9qV6SPNDW7oW WfZdvtFKhj3A+cXikrtjrWs0xOt8ih2DdcnU2sLLREsA+5xZXOPF3Q0Pq23z/c0bZkjzkb 0ilnn0PNNv30c292sgibjg6cwyJrGWA= Received: from mail-il1-f199.google.com (mail-il1-f199.google.com [209.85.166.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-474-7o_3p-wePYSjsqkb_oZBfw-1; Thu, 16 Jun 2022 21:41:56 -0400 X-MC-Unique: 7o_3p-wePYSjsqkb_oZBfw-1 Received: by mail-il1-f199.google.com with SMTP id k15-20020a056e021a8f00b002d79963e53fso1818257ilv.14 for ; Thu, 16 Jun 2022 18:41:56 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=bR8MuwpznI9qRUj89FotcZKYXyQ5fO5vJmhSv17cXWQ=; b=lOHdyUlD+b8TMeerPO6BMhupfuq+GZCpjTjuTpTJX5lZOfMHhL23zqrs2wANUAnwRx dz1+Rsxervb0Ws8aN/yGWsCLqCDBVt7+pWNDY0IwXSnoX2Kb+g9zifpJiaUFl+u7e3iy ZHSEP0NemeZMOSD6R/y6w1rNGuED60EdvygJ4I1dtjNIl0M3tJEsOwKAqeqoQU93IzRT 7LJoweouaY8nw7uJKp5Vcr4ewGtdeXQ/BB5aICEk0b/cPB62OgQ6r+BlG/2/ukKcqOcl Sog6cEVSaI0QPzpuTYroRAyJb++ReYSeBUNeg2iCQ7AFxtvtzS/+Ux3T2mo6vmZRErMC DQkw== X-Gm-Message-State: AJIora9Sm05WA4SqD9cQY8i7vZD2Oe0PDeP9NKP0W42Qxi+gCf/vLsfT 9JV/P7yRTFyPLYbIcqwl24GV6F8NjO3tt/YU2imkcGU4ZzhXx0QBxf87+AuYzzqHgxRDlOQIZi3 jqzW6BBa7JVxd0OrKD9iISROq0RkmFF357sN6pB3Rj6Kfg72luGKDCJ1zy912Tw== X-Received: by 2002:a92:ca0b:0:b0:2d1:ed7a:a1fc with SMTP id j11-20020a92ca0b000000b002d1ed7aa1fcmr4338230ils.282.1655430114602; Thu, 16 Jun 2022 18:41:54 -0700 (PDT) X-Google-Smtp-Source: AGRyM1spYww9dWZVjK4wNwAz3pACZhgd3fjV/WAPqh1xL4lB2Vo7rp9WsWx7H9mGd00hnV7NGDXT3A== X-Received: by 2002:a92:ca0b:0:b0:2d1:ed7a:a1fc with SMTP id j11-20020a92ca0b000000b002d1ed7aa1fcmr4338213ils.282.1655430114178; Thu, 16 Jun 2022 18:41:54 -0700 (PDT) Received: from localhost.localdomain (cpec09435e3e0ee-cmc09435e3e0ec.cpe.net.cable.rogers.com. [99.241.198.116]) by smtp.gmail.com with ESMTPSA id n4-20020a056e02140400b002d522958fb4sm1726538ilo.2.2022.06.16.18.41.52 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 16 Jun 2022 18:41:53 -0700 (PDT) From: Peter Xu To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "Dr . David Alan Gilbert" , Linux MM Mailing List , Sean Christopherson , Paolo Bonzini , Andrea Arcangeli , Andrew Morton , peterx@redhat.com Subject: [PATCH RFC 2/4] kvm: Merge "atomic" and "write" in __gfn_to_pfn_memslot() Date: Thu, 16 Jun 2022 21:41:45 -0400 Message-Id: <20220617014147.7299-3-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220617014147.7299-1-peterx@redhat.com> References: <20220617014147.7299-1-peterx@redhat.com> MIME-Version: 1.0 Content-type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Merge two boolean parameters into a bitmask flag called kvm_gtp_flag_t for __gfn_to_pfn_memslot(). This cleans the parameter lists, and also prepare for new boolean to be added to __gfn_to_pfn_memslot(). Signed-off-by: Peter Xu --- arch/arm64/kvm/mmu.c | 5 ++-- arch/powerpc/kvm/book3s_64_mmu_hv.c | 5 ++-- arch/powerpc/kvm/book3s_64_mmu_radix.c | 5 ++-- arch/x86/kvm/mmu/mmu.c | 10 +++---- include/linux/kvm_host.h | 9 ++++++- virt/kvm/kvm_main.c | 37 +++++++++++++++----------- virt/kvm/kvm_mm.h | 6 +++-- virt/kvm/pfncache.c | 2 +- 8 files changed, 49 insertions(+), 30 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index f5651a05b6a8..ce8066ded15b 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1204,8 +1204,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, */ smp_rmb(); - pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL, - write_fault, &writable, NULL); + pfn = __gfn_to_pfn_memslot(memslot, gfn, + write_fault ? KVM_GTP_WRITE : 0, + false, NULL, &writable, NULL); if (pfn == KVM_PFN_ERR_HWPOISON) { kvm_send_hwpoison_signal(hva, vma_shift); return 0; diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 514fd45c1994..2f5fad2e1b7f 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -598,8 +598,9 @@ int kvmppc_book3s_hv_page_fault(struct kvm_vcpu *vcpu, write_ok = true; } else { /* Call KVM generic code to do the slow-path check */ - pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL, - writing, &write_ok, NULL); + pfn = __gfn_to_pfn_memslot(memslot, gfn, + writing ? KVM_GTP_WRITE : 0, + false, NULL, &write_ok, NULL); if (is_error_noslot_pfn(pfn)) return -EFAULT; page = NULL; diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c index 42851c32ff3b..232b17c75b83 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c @@ -845,8 +845,9 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu, unsigned long pfn; /* Call KVM generic code to do the slow-path check */ - pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL, - writing, upgrade_p, NULL); + pfn = __gfn_to_pfn_memslot(memslot, gfn, + writing ? KVM_GTP_WRITE : 0, + NULL, upgrade_p, NULL); if (is_error_noslot_pfn(pfn)) return -EFAULT; page = NULL; diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index f4653688fa6d..e92f1ab63d6a 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3968,6 +3968,7 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { + kvm_gtp_flag_t flags = fault->write ? KVM_GTP_WRITE : 0; struct kvm_memory_slot *slot = fault->slot; bool async; @@ -3999,8 +4000,8 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) } async = false; - fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, &async, - fault->write, &fault->map_writable, + fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, flags, + &async, &fault->map_writable, &fault->hva); if (!async) return RET_PF_CONTINUE; /* *pfn has correct page already */ @@ -4016,9 +4017,8 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) } } - fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, NULL, - fault->write, &fault->map_writable, - &fault->hva); + fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, flags, NULL, + &fault->map_writable, &fault->hva); return RET_PF_CONTINUE; } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index c20f2d55840c..b646b6fcaec6 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1146,8 +1146,15 @@ kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault, bool *writable); kvm_pfn_t gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn); kvm_pfn_t gfn_to_pfn_memslot_atomic(const struct kvm_memory_slot *slot, gfn_t gfn); + +/* gfn_to_pfn (gtp) flags */ +typedef unsigned int __bitwise kvm_gtp_flag_t; + +#define KVM_GTP_WRITE ((__force kvm_gtp_flag_t) BIT(0)) +#define KVM_GTP_ATOMIC ((__force kvm_gtp_flag_t) BIT(1)) + kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn, - bool atomic, bool *async, bool write_fault, + kvm_gtp_flag_t gtp_flags, bool *async, bool *writable, hva_t *hva); void kvm_release_pfn_clean(kvm_pfn_t pfn); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 64ec2222a196..952400b42ee9 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2444,9 +2444,11 @@ static bool hva_to_pfn_fast(unsigned long addr, bool write_fault, * The slow path to get the pfn of the specified host virtual address, * 1 indicates success, -errno is returned if error is detected. */ -static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault, +static int hva_to_pfn_slow(unsigned long addr, bool *async, + kvm_gtp_flag_t gtp_flags, bool *writable, kvm_pfn_t *pfn) { + bool write_fault = gtp_flags & KVM_GTP_WRITE; unsigned int flags = FOLL_HWPOISON; struct page *page; int npages = 0; @@ -2565,20 +2567,22 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma, /* * Pin guest page in memory and return its pfn. * @addr: host virtual address which maps memory to the guest - * @atomic: whether this function can sleep + * @gtp_flags: kvm_gtp_flag_t flags (atomic, write, ..) * @async: whether this function need to wait IO complete if the * host page is not in the memory - * @write_fault: whether we should get a writable host page * @writable: whether it allows to map a writable host page for !@write_fault * - * The function will map a writable host page for these two cases: + * The function will map a writable (KVM_GTP_WRITE set) host page for these + * two cases: * 1): @write_fault = true * 2): @write_fault = false && @writable, @writable will tell the caller * whether the mapping is writable. */ -kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, - bool write_fault, bool *writable) +kvm_pfn_t hva_to_pfn(unsigned long addr, kvm_gtp_flag_t gtp_flags, bool *async, + bool *writable) { + bool write_fault = gtp_flags & KVM_GTP_WRITE; + bool atomic = gtp_flags & KVM_GTP_ATOMIC; struct vm_area_struct *vma; kvm_pfn_t pfn = 0; int npages, r; @@ -2592,7 +2596,7 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, if (atomic) return KVM_PFN_ERR_FAULT; - npages = hva_to_pfn_slow(addr, async, write_fault, writable, &pfn); + npages = hva_to_pfn_slow(addr, async, gtp_flags, writable, &pfn); if (npages == 1) return pfn; @@ -2625,10 +2629,11 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, } kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn, - bool atomic, bool *async, bool write_fault, + kvm_gtp_flag_t gtp_flags, bool *async, bool *writable, hva_t *hva) { - unsigned long addr = __gfn_to_hva_many(slot, gfn, NULL, write_fault); + unsigned long addr = __gfn_to_hva_many(slot, gfn, NULL, + gtp_flags & KVM_GTP_WRITE); if (hva) *hva = addr; @@ -2651,28 +2656,30 @@ kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn, writable = NULL; } - return hva_to_pfn(addr, atomic, async, write_fault, - writable); + return hva_to_pfn(addr, gtp_flags, async, writable); } EXPORT_SYMBOL_GPL(__gfn_to_pfn_memslot); kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault, bool *writable) { - return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn, false, NULL, - write_fault, writable, NULL); + return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn, + write_fault ? KVM_GTP_WRITE : 0, + NULL, writable, NULL); } EXPORT_SYMBOL_GPL(gfn_to_pfn_prot); kvm_pfn_t gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn) { - return __gfn_to_pfn_memslot(slot, gfn, false, NULL, true, NULL, NULL); + return __gfn_to_pfn_memslot(slot, gfn, KVM_GTP_WRITE, + NULL, NULL, NULL); } EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot); kvm_pfn_t gfn_to_pfn_memslot_atomic(const struct kvm_memory_slot *slot, gfn_t gfn) { - return __gfn_to_pfn_memslot(slot, gfn, true, NULL, true, NULL, NULL); + return __gfn_to_pfn_memslot(slot, gfn, KVM_GTP_WRITE | KVM_GTP_ATOMIC, + NULL, NULL, NULL); } EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot_atomic); diff --git a/virt/kvm/kvm_mm.h b/virt/kvm/kvm_mm.h index 41da467d99c9..1c870911eb48 100644 --- a/virt/kvm/kvm_mm.h +++ b/virt/kvm/kvm_mm.h @@ -3,6 +3,8 @@ #ifndef __KVM_MM_H__ #define __KVM_MM_H__ 1 +#include + /* * Architectures can choose whether to use an rwlock or spinlock * for the mmu_lock. These macros, for use in common code @@ -24,8 +26,8 @@ #define KVM_MMU_READ_UNLOCK(kvm) spin_unlock(&(kvm)->mmu_lock) #endif /* KVM_HAVE_MMU_RWLOCK */ -kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, - bool write_fault, bool *writable); +kvm_pfn_t hva_to_pfn(unsigned long addr, kvm_gtp_flag_t gtp_flags, bool *async, + bool *writable); #ifdef CONFIG_HAVE_KVM_PFNCACHE void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index dd84676615f1..0f9f6b5d2fbb 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -123,7 +123,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct kvm *kvm, unsigned long uhva) smp_rmb(); /* We always request a writeable mapping */ - new_pfn = hva_to_pfn(uhva, false, NULL, true, NULL); + new_pfn = hva_to_pfn(uhva, KVM_GTP_WRITE, NULL, NULL); if (is_error_noslot_pfn(new_pfn)) break; From patchwork Fri Jun 17 01:41:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Xu X-Patchwork-Id: 12885030 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 71327C433EF for ; Fri, 17 Jun 2022 01:42:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379588AbiFQBmQ (ORCPT ); Thu, 16 Jun 2022 21:42:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35318 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1379458AbiFQBmB (ORCPT ); Thu, 16 Jun 2022 21:42:01 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4D2A263BD7 for ; Thu, 16 Jun 2022 18:42:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655430119; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ghHac7UV1N6vPGfjk7ojRXZFbMUyEtSeJQo5S/wAoOg=; b=UrS3mwPEcs57xDdDkIykHFCj1GTK5Lk8UVCsdou1GwUeeQVytItXPFp321+7kCaqqG7P3A FucUGVETLCwrF1Vpa/pvzT3GjZ0kO43aZwave4rqWHLL2VBKEV22AfUANII7dcemPklRsu RqTS9dh3eaz6/pxfkajXPUAp1WQ1XsM= Received: from mail-il1-f200.google.com (mail-il1-f200.google.com [209.85.166.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-267-VR95ee9kOjCqRErhvPE5WQ-1; Thu, 16 Jun 2022 21:41:57 -0400 X-MC-Unique: VR95ee9kOjCqRErhvPE5WQ-1 Received: by mail-il1-f200.google.com with SMTP id e4-20020a056e020b2400b002d5509de6f3so1827568ilu.6 for ; Thu, 16 Jun 2022 18:41:57 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ghHac7UV1N6vPGfjk7ojRXZFbMUyEtSeJQo5S/wAoOg=; b=Hjyq5fjDtTYKEaj4avcmAPu2NrM7UT8ZMyULVo7nP/eil7JLhjxiz+pHfhHadV9+Nx 9HmvS2v5o4nQC8mPhPtPiMpmK9f4fekJehPQe8OxzwxIBJDOevNMq+joOaqMqKpdHejU xw1z4skAWMg6VArYB88xq3wV7OvCJ6XxafR4fDxQ+NbT2fBn8SiIUlBGjhbg4qnrzyAY kIi/y6Pu8hEsLietjseS9ONyj2tzER8BHdkr3YnJCuX382oai7+xkY18nOa6hlE5mhDK aAJL5SJ4sUEj+XHCDr0KBSWvFnHAvpT+uCgN7lGIH8uH4NWONe55SmJWbt4kINp/7+oQ +54Q== X-Gm-Message-State: AJIora9G09nh2jbIF5R8O9M6OEt4EMNlaKexTbcmk/c2/qaYIwmhdbez AhdcLdaLF3a7uQw2FvEoIQjXRABy2iPwICArjBA/kL7FuOYMF3cbcssnkcT/u8KLRTMDcxq69ti J5c4c+2D2Wg252Jcm2S2nXAu4iiyjF06hhu0wuiYr8CL/JUOj4tng+9RxdH4pJw== X-Received: by 2002:a05:6e02:811:b0:2d5:2294:ff37 with SMTP id u17-20020a056e02081100b002d52294ff37mr4319995ilm.249.1655430116808; Thu, 16 Jun 2022 18:41:56 -0700 (PDT) X-Google-Smtp-Source: AGRyM1vkkfMz7cqp5MF8GJOCZIECqzgeFNO0MvlQHMdn1ovMhxzPuVoVfsfN47FOLsLaed4L90CO1w== X-Received: by 2002:a05:6e02:811:b0:2d5:2294:ff37 with SMTP id u17-20020a056e02081100b002d52294ff37mr4319979ilm.249.1655430116477; Thu, 16 Jun 2022 18:41:56 -0700 (PDT) Received: from localhost.localdomain (cpec09435e3e0ee-cmc09435e3e0ec.cpe.net.cable.rogers.com. [99.241.198.116]) by smtp.gmail.com with ESMTPSA id n4-20020a056e02140400b002d522958fb4sm1726538ilo.2.2022.06.16.18.41.54 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 16 Jun 2022 18:41:56 -0700 (PDT) From: Peter Xu To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "Dr . David Alan Gilbert" , Linux MM Mailing List , Sean Christopherson , Paolo Bonzini , Andrea Arcangeli , Andrew Morton , peterx@redhat.com Subject: [PATCH RFC 3/4] kvm: Add new pfn error KVM_PFN_ERR_INTR Date: Thu, 16 Jun 2022 21:41:46 -0400 Message-Id: <20220617014147.7299-4-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220617014147.7299-1-peterx@redhat.com> References: <20220617014147.7299-1-peterx@redhat.com> MIME-Version: 1.0 Content-type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Add one new PFN error type to show when we cannot finish fetching the PFN due to interruptions. For example, by receiving a generic signal. This prepares KVM to be able to respond to SIGUSR1 (for QEMU that's the SIGIPI) even during e.g. handling an userfaultfd page fault. Signed-off-by: Peter Xu --- include/linux/kvm_host.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index b646b6fcaec6..4f84a442f67f 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -96,6 +96,7 @@ #define KVM_PFN_ERR_FAULT (KVM_PFN_ERR_MASK) #define KVM_PFN_ERR_HWPOISON (KVM_PFN_ERR_MASK + 1) #define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 2) +#define KVM_PFN_ERR_INTR (KVM_PFN_ERR_MASK + 3) /* * error pfns indicate that the gfn is in slot but faild to @@ -106,6 +107,16 @@ static inline bool is_error_pfn(kvm_pfn_t pfn) return !!(pfn & KVM_PFN_ERR_MASK); } +/* + * When KVM_PFN_ERR_INTR is returned, it means we're interrupted during + * fetching the PFN (e.g. a signal might have arrived), so we may want to + * retry at some later point and kick the userspace to handle the signal. + */ +static inline bool is_intr_pfn(kvm_pfn_t pfn) +{ + return pfn == KVM_PFN_ERR_INTR; +} + /* * error_noslot pfns indicate that the gfn can not be * translated to pfn - it is not in slot or failed to From patchwork Fri Jun 17 01:41:47 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Xu X-Patchwork-Id: 12885031 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE636C43334 for ; Fri, 17 Jun 2022 01:42:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379614AbiFQBmR (ORCPT ); Thu, 16 Jun 2022 21:42:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1379568AbiFQBmD (ORCPT ); Thu, 16 Jun 2022 21:42:03 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5D52863BD8 for ; Thu, 16 Jun 2022 18:42:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655430120; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+Bc6oiDMKyczPP3MnRg+YG2Ibpmu1/F27D1fgoc2Uo0=; b=gDXBZOScJ2sU5KdARbajqNpssaqmuZygbU3NXTjKvQM0uE+uidQVbv3plJgby4JCgNb7/Y HwSigMBWHRS2GqHNeEaRnrDT9U/tYOvQXyWstG2jk65clq6/O/a3LfwEsjW/0NWcvttmGb AmxwNM1xL/5keODuErkn0BVc6vzKZ4Y= Received: from mail-io1-f71.google.com (mail-io1-f71.google.com [209.85.166.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-657-HBN4oqHLOz-6ArOPbC_Pkg-1; Thu, 16 Jun 2022 21:41:59 -0400 X-MC-Unique: HBN4oqHLOz-6ArOPbC_Pkg-1 Received: by mail-io1-f71.google.com with SMTP id l7-20020a6b7007000000b00669b2a0d497so1790151ioc.0 for ; Thu, 16 Jun 2022 18:41:59 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=+Bc6oiDMKyczPP3MnRg+YG2Ibpmu1/F27D1fgoc2Uo0=; b=jm94qEqTiK+4i383kcudIU8cgcw6fgZ5q5JoCa7R19IZ142bvGrO1HTsds9L1uqaXz Tzvxamy1WAli5J1ycJFiG/VQNx+BwtdiFmCC+Cc22ocy150A0pxOMLGUPThqqqYBabPT PCH2jPAgsbc2urYSrv92Px0MACpb18rWP7P2q4aFhEtLQ+cGcOMKUtmINS1/8TgeL1ce e8MzFDgaTQJgUVjCue7Yf5yzb/tVogRcFLsv4LT8wRqGI9APk4B/pxUsRB/lYdK9iWBA YDkGtpDPHtCQAp9HfYn/JrIx7V8JPqkqb1zBntIhaQ4xXNKLN55HTGkOb+oacgdra7sX 7cNQ== X-Gm-Message-State: AJIora83UZcsfWiVmblB0ddhtK18GJR6XZQwjRQyyknj7H44XGcPalwS qo2Bx8XupZLYgBDdRgveRunZzAcDaT2due8keQ3Wd8D/OIES8I+R3uuAn6givHHuw52U23WI4y5 cXefigqo4AV0K/zR0mJMhL2cy1Ob4wqjyBob0sJGeLk8ueVbAUoM4Ipszjn8dsQ== X-Received: by 2002:a92:da4e:0:b0:2d6:6554:a33b with SMTP id p14-20020a92da4e000000b002d66554a33bmr4355228ilq.10.1655430118330; Thu, 16 Jun 2022 18:41:58 -0700 (PDT) X-Google-Smtp-Source: AGRyM1vLhgSniNb4wQ9rsYIx2n9iJ0unph2M/HKN3cx1HhnNV8Tgz+efjRctqDyhOiUvQlicAOOc3w== X-Received: by 2002:a92:da4e:0:b0:2d6:6554:a33b with SMTP id p14-20020a92da4e000000b002d66554a33bmr4355213ilq.10.1655430117980; Thu, 16 Jun 2022 18:41:57 -0700 (PDT) Received: from localhost.localdomain (cpec09435e3e0ee-cmc09435e3e0ec.cpe.net.cable.rogers.com. [99.241.198.116]) by smtp.gmail.com with ESMTPSA id n4-20020a056e02140400b002d522958fb4sm1726538ilo.2.2022.06.16.18.41.56 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 16 Jun 2022 18:41:57 -0700 (PDT) From: Peter Xu To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "Dr . David Alan Gilbert" , Linux MM Mailing List , Sean Christopherson , Paolo Bonzini , Andrea Arcangeli , Andrew Morton , peterx@redhat.com Subject: [PATCH RFC 4/4] kvm/x86: Allow to respond to generic signals during slow page faults Date: Thu, 16 Jun 2022 21:41:47 -0400 Message-Id: <20220617014147.7299-5-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220617014147.7299-1-peterx@redhat.com> References: <20220617014147.7299-1-peterx@redhat.com> MIME-Version: 1.0 Content-type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org All the facilities should be ready for this, what we need to do is to add a new KVM_GTP_INTERRUPTIBLE flag showing that we're willing to be interrupted by common signals during the __gfn_to_pfn_memslot() request, and wire it up with a FOLL_INTERRUPTIBLE flag that we've just introduced. Note that only x86 slow page fault routine will set this new bit. The new bit is not used in non-x86 arch or on other gup paths even for x86. However it can actually be used elsewhere too but not yet covered. When we see the PFN fetching was interrupted, do early exit to userspace with an KVM_EXIT_INTR exit reason. Signed-off-by: Peter Xu --- arch/x86/kvm/mmu/mmu.c | 9 +++++++++ include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 4 ++++ 3 files changed, 14 insertions(+) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index e92f1ab63d6a..b39acb7cb16d 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3012,6 +3012,13 @@ static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn) static int handle_abnormal_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, unsigned int access) { + /* NOTE: not all error pfn is fatal; handle intr before the other ones */ + if (unlikely(is_intr_pfn(fault->pfn))) { + vcpu->run->exit_reason = KVM_EXIT_INTR; + ++vcpu->stat.signal_exits; + return -EINTR; + } + /* The pfn is invalid, report the error! */ if (unlikely(is_error_pfn(fault->pfn))) return kvm_handle_bad_page(vcpu, fault->gfn, fault->pfn); @@ -4017,6 +4024,8 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) } } + /* Allow to respond to generic signals in slow page faults */ + flags |= KVM_GTP_INTERRUPTIBLE; fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, flags, NULL, &fault->map_writable, &fault->hva); return RET_PF_CONTINUE; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 4f84a442f67f..c8d98e435537 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1163,6 +1163,7 @@ typedef unsigned int __bitwise kvm_gtp_flag_t; #define KVM_GTP_WRITE ((__force kvm_gtp_flag_t) BIT(0)) #define KVM_GTP_ATOMIC ((__force kvm_gtp_flag_t) BIT(1)) +#define KVM_GTP_INTERRUPTIBLE ((__force kvm_gtp_flag_t) BIT(2)) kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn, kvm_gtp_flag_t gtp_flags, bool *async, diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 952400b42ee9..b3873cac5672 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2462,6 +2462,8 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, flags |= FOLL_WRITE; if (async) flags |= FOLL_NOWAIT; + if (gtp_flags & KVM_GTP_INTERRUPTIBLE) + flags |= FOLL_INTERRUPTIBLE; npages = get_user_pages_unlocked(addr, 1, &page, flags); if (npages != 1) @@ -2599,6 +2601,8 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, kvm_gtp_flag_t gtp_flags, bool *async, npages = hva_to_pfn_slow(addr, async, gtp_flags, writable, &pfn); if (npages == 1) return pfn; + if (npages == -EINTR) + return KVM_PFN_ERR_INTR; mmap_read_lock(current->mm); if (npages == -EHWPOISON ||