From patchwork Tue Nov 8 04:10:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gavin Shan X-Patchwork-Id: 13035830 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 94C51C4332F for ; Tue, 8 Nov 2022 04:13:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232939AbiKHENZ (ORCPT ); Mon, 7 Nov 2022 23:13:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43484 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232381AbiKHENX (ORCPT ); Mon, 7 Nov 2022 23:13:23 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9670A15FD2 for ; Mon, 7 Nov 2022 20:12:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1667880746; 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=zHFWHrDPitAZ2CFICQlKxokmuu7CotBRVEubYjCqj1c=; b=bm8YDfw2WCDbvACt7g9g35RMamY5yRa9csCiHIMR9v+jB6O6kZjwJRsckz+RcBoqWZ8+iu hdN58FGh2zu1XeCdXOI8vopBcdYVUnF80Zmkw+qfIJS9K/Jj3JLHhBrc+GDyeriVVIIxOa rL7fOKbQDXlu+XdqvdrMKwzNzQovTG4= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-664-d6ytsOAcOeeDwCl1-gHcXA-1; Mon, 07 Nov 2022 23:12:23 -0500 X-MC-Unique: d6ytsOAcOeeDwCl1-gHcXA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8FC30811E7A; Tue, 8 Nov 2022 04:12:22 +0000 (UTC) Received: from gshan.redhat.com (vpn2-54-78.bne.redhat.com [10.64.54.78]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3682535429; Tue, 8 Nov 2022 04:12:15 +0000 (UTC) From: Gavin Shan To: kvmarm@lists.linux.dev Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, shuah@kernel.org, catalin.marinas@arm.com, andrew.jones@linux.dev, ajones@ventanamicro.com, bgardon@google.com, dmatlack@google.com, will@kernel.org, suzuki.poulose@arm.com, alexandru.elisei@arm.com, pbonzini@redhat.com, maz@kernel.org, peterx@redhat.com, oliver.upton@linux.dev, seanjc@google.com, zhenyzha@redhat.com, shan.gavin@gmail.com Subject: [PATCH v9 1/7] KVM: x86: Introduce KVM_REQ_DIRTY_RING_SOFT_FULL Date: Tue, 8 Nov 2022 12:10:33 +0800 Message-Id: <20221108041039.111145-2-gshan@redhat.com> In-Reply-To: <20221108041039.111145-1-gshan@redhat.com> References: <20221108041039.111145-1-gshan@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org The VCPU isn't expected to be runnable when the dirty ring becomes soft full, until the dirty pages are harvested and the dirty ring is reset from userspace. So there is a check in each guest's entrace to see if the dirty ring is soft full or not. The VCPU is stopped from running if its dirty ring has been soft full. The similar check will be needed when the feature is going to be supported on ARM64. As Marc Zyngier suggested, a new event will avoid pointless overhead to check the size of the dirty ring ('vcpu->kvm->dirty_ring_size') in each guest's entrance. Add KVM_REQ_DIRTY_RING_SOFT_FULL. The event is raised when the dirty ring becomes soft full in kvm_dirty_ring_push(). The event is only cleared in the check, done in the newly added helper kvm_dirty_ring_check_request(). Since the VCPU is not runnable when the dirty ring becomes soft full, the KVM_REQ_DIRTY_RING_SOFT_FULL event is always set to prevent the VCPU from running until the dirty pages are harvested and the dirty ring is reset by userspace. kvm_dirty_ring_soft_full() becomes a private function with the newly added helper kvm_dirty_ring_check_request(). The alignment for the various event definitions in kvm_host.h is changed to tab character by the way. In order to avoid using 'container_of()', the argument @ring is replaced by @vcpu in kvm_dirty_ring_push(). Link: https://lore.kernel.org/kvmarm/87lerkwtm5.wl-maz@kernel.org Suggested-by: Marc Zyngier Signed-off-by: Gavin Shan Reviewed-by: Peter Xu Reviewed-by: Sean Christopherson --- arch/x86/kvm/x86.c | 15 ++++++--------- include/linux/kvm_dirty_ring.h | 12 ++++-------- include/linux/kvm_host.h | 9 +++++---- virt/kvm/dirty_ring.c | 32 ++++++++++++++++++++++++++++++-- virt/kvm/kvm_main.c | 3 +-- 5 files changed, 46 insertions(+), 25 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 5f5eb577d583..a228a1b872bb 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10515,20 +10515,17 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) bool req_immediate_exit = false; - /* Forbid vmenter if vcpu dirty ring is soft-full */ - if (unlikely(vcpu->kvm->dirty_ring_size && - kvm_dirty_ring_soft_full(&vcpu->dirty_ring))) { - vcpu->run->exit_reason = KVM_EXIT_DIRTY_RING_FULL; - trace_kvm_dirty_ring_exit(vcpu); - r = 0; - goto out; - } - if (kvm_request_pending(vcpu)) { if (kvm_check_request(KVM_REQ_VM_DEAD, vcpu)) { r = -EIO; goto out; } + + if (kvm_dirty_ring_check_request(vcpu)) { + r = 0; + goto out; + } + if (kvm_check_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu)) { if (unlikely(!kvm_x86_ops.nested_ops->get_nested_state_pages(vcpu))) { r = 0; diff --git a/include/linux/kvm_dirty_ring.h b/include/linux/kvm_dirty_ring.h index 906f899813dc..9c13c4c3d30c 100644 --- a/include/linux/kvm_dirty_ring.h +++ b/include/linux/kvm_dirty_ring.h @@ -49,7 +49,7 @@ static inline int kvm_dirty_ring_reset(struct kvm *kvm, return 0; } -static inline void kvm_dirty_ring_push(struct kvm_dirty_ring *ring, +static inline void kvm_dirty_ring_push(struct kvm_vcpu *vcpu, u32 slot, u64 offset) { } @@ -64,11 +64,6 @@ static inline void kvm_dirty_ring_free(struct kvm_dirty_ring *ring) { } -static inline bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring) -{ - return true; -} - #else /* CONFIG_HAVE_KVM_DIRTY_RING */ u32 kvm_dirty_ring_get_rsvd_entries(void); @@ -84,13 +79,14 @@ int kvm_dirty_ring_reset(struct kvm *kvm, struct kvm_dirty_ring *ring); * returns =0: successfully pushed * <0: unable to push, need to wait */ -void kvm_dirty_ring_push(struct kvm_dirty_ring *ring, u32 slot, u64 offset); +void kvm_dirty_ring_push(struct kvm_vcpu *vcpu, u32 slot, u64 offset); + +bool kvm_dirty_ring_check_request(struct kvm_vcpu *vcpu); /* for use in vm_operations_struct */ struct page *kvm_dirty_ring_get_page(struct kvm_dirty_ring *ring, u32 offset); void kvm_dirty_ring_free(struct kvm_dirty_ring *ring); -bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring); #endif /* CONFIG_HAVE_KVM_DIRTY_RING */ diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 18592bdf4c1b..6fab55e58111 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -153,10 +153,11 @@ static inline bool is_error_page(struct page *page) * Architecture-independent vcpu->requests bit members * Bits 3-7 are reserved for more arch-independent bits. */ -#define KVM_REQ_TLB_FLUSH (0 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) -#define KVM_REQ_VM_DEAD (1 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) -#define KVM_REQ_UNBLOCK 2 -#define KVM_REQUEST_ARCH_BASE 8 +#define KVM_REQ_TLB_FLUSH (0 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) +#define KVM_REQ_VM_DEAD (1 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) +#define KVM_REQ_UNBLOCK 2 +#define KVM_REQ_DIRTY_RING_SOFT_FULL 3 +#define KVM_REQUEST_ARCH_BASE 8 /* * KVM_REQ_OUTSIDE_GUEST_MODE exists is purely as way to force the vCPU to diff --git a/virt/kvm/dirty_ring.c b/virt/kvm/dirty_ring.c index d6fabf238032..fecbb7d75ad2 100644 --- a/virt/kvm/dirty_ring.c +++ b/virt/kvm/dirty_ring.c @@ -26,7 +26,7 @@ static u32 kvm_dirty_ring_used(struct kvm_dirty_ring *ring) return READ_ONCE(ring->dirty_index) - READ_ONCE(ring->reset_index); } -bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring) +static bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring) { return kvm_dirty_ring_used(ring) >= ring->soft_limit; } @@ -142,13 +142,19 @@ int kvm_dirty_ring_reset(struct kvm *kvm, struct kvm_dirty_ring *ring) kvm_reset_dirty_gfn(kvm, cur_slot, cur_offset, mask); + /* + * The request KVM_REQ_DIRTY_RING_SOFT_FULL will be cleared + * by the VCPU thread next time when it enters the guest. + */ + trace_kvm_dirty_ring_reset(ring); return count; } -void kvm_dirty_ring_push(struct kvm_dirty_ring *ring, u32 slot, u64 offset) +void kvm_dirty_ring_push(struct kvm_vcpu *vcpu, u32 slot, u64 offset) { + struct kvm_dirty_ring *ring = &vcpu->dirty_ring; struct kvm_dirty_gfn *entry; /* It should never get full */ @@ -166,6 +172,28 @@ void kvm_dirty_ring_push(struct kvm_dirty_ring *ring, u32 slot, u64 offset) kvm_dirty_gfn_set_dirtied(entry); ring->dirty_index++; trace_kvm_dirty_ring_push(ring, slot, offset); + + if (kvm_dirty_ring_soft_full(ring)) + kvm_make_request(KVM_REQ_DIRTY_RING_SOFT_FULL, vcpu); +} + +bool kvm_dirty_ring_check_request(struct kvm_vcpu *vcpu) +{ + /* + * The VCPU isn't runnable when the dirty ring becomes soft full. + * The KVM_REQ_DIRTY_RING_SOFT_FULL event is always set to prevent + * the VCPU from running until the dirty pages are harvested and + * the dirty ring is reset by userspace. + */ + if (kvm_check_request(KVM_REQ_DIRTY_RING_SOFT_FULL, vcpu) && + kvm_dirty_ring_soft_full(&vcpu->dirty_ring)) { + kvm_make_request(KVM_REQ_DIRTY_RING_SOFT_FULL, vcpu); + vcpu->run->exit_reason = KVM_EXIT_DIRTY_RING_FULL; + trace_kvm_dirty_ring_exit(vcpu); + return true; + } + + return false; } struct page *kvm_dirty_ring_get_page(struct kvm_dirty_ring *ring, u32 offset) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 25d7872b29c1..c865d7d82685 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3314,8 +3314,7 @@ void mark_page_dirty_in_slot(struct kvm *kvm, u32 slot = (memslot->as_id << 16) | memslot->id; if (kvm->dirty_ring_size) - kvm_dirty_ring_push(&vcpu->dirty_ring, - slot, rel_gfn); + kvm_dirty_ring_push(vcpu, slot, rel_gfn); else set_bit_le(rel_gfn, memslot->dirty_bitmap); }