linux-kernel - [PATCH v3 21/31] KVM: x86/mmu: Avoid memslot lookup in page_fault_handle_page

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Message-Id: <20210924163152.289027-22-pbonzini@redhat.com>
Date:   Fri, 24 Sep 2021 12:31:42 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     dmatlack@...gle.com, seanjc@...gle.com
Subject: [PATCH v3 21/31] KVM: x86/mmu: Avoid memslot lookup in page_fault_handle_page_track

From: David Matlack <dmatlack@...gle.com>

Now that kvm_page_fault has a pointer to the memslot it can be passed
down to the page tracking code to avoid a redundant slot lookup.

No functional change intended.

Signed-off-by: David Matlack <dmatlack@...gle.com>
Message-Id: <20210813203504.2742757-5-dmatlack@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/include/asm/kvm_page_track.h |  2 ++
 arch/x86/kvm/mmu/mmu.c                |  2 +-
 arch/x86/kvm/mmu/page_track.c         | 20 +++++++++++++-------
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h
index 6a5f3acf2b33..9cd9230e5cc8 100644
--- a/arch/x86/include/asm/kvm_page_track.h
+++ b/arch/x86/include/asm/kvm_page_track.h
@@ -61,6 +61,8 @@ void kvm_slot_page_track_remove_page(struct kvm *kvm,
 				     enum kvm_page_track_mode mode);
 bool kvm_page_track_is_active(struct kvm_vcpu *vcpu, gfn_t gfn,
 			      enum kvm_page_track_mode mode);
+bool kvm_slot_page_track_is_active(struct kvm_memory_slot *slot, gfn_t gfn,
+				   enum kvm_page_track_mode mode);
 
 void
 kvm_page_track_register_notifier(struct kvm *kvm,
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 754578458cb7..d63fe7b10bd1 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3819,7 +3819,7 @@ static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu,
 	 * guest is writing the page which is write tracked which can
 	 * not be fixed by page fault handler.
 	 */
-	if (kvm_page_track_is_active(vcpu, fault->gfn, KVM_PAGE_TRACK_WRITE))
+	if (kvm_slot_page_track_is_active(fault->slot, fault->gfn, KVM_PAGE_TRACK_WRITE))
 		return true;
 
 	return false;
diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c
index 21427e84a82e..859800f7bb95 100644
--- a/arch/x86/kvm/mmu/page_track.c
+++ b/arch/x86/kvm/mmu/page_track.c
@@ -136,19 +136,14 @@ void kvm_slot_page_track_remove_page(struct kvm *kvm,
 }
 EXPORT_SYMBOL_GPL(kvm_slot_page_track_remove_page);
 
-/*
- * check if the corresponding access on the specified guest page is tracked.
- */
-bool kvm_page_track_is_active(struct kvm_vcpu *vcpu, gfn_t gfn,
-			      enum kvm_page_track_mode mode)
+bool kvm_slot_page_track_is_active(struct kvm_memory_slot *slot, gfn_t gfn,
+				   enum kvm_page_track_mode mode)
 {
-	struct kvm_memory_slot *slot;
 	int index;
 
 	if (WARN_ON(!page_track_mode_is_valid(mode)))
 		return false;
 
-	slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
 	if (!slot)
 		return false;
 
@@ -156,6 +151,17 @@ bool kvm_page_track_is_active(struct kvm_vcpu *vcpu, gfn_t gfn,
 	return !!READ_ONCE(slot->arch.gfn_track[mode][index]);
 }
 
+/*
+ * check if the corresponding access on the specified guest page is tracked.
+ */
+bool kvm_page_track_is_active(struct kvm_vcpu *vcpu, gfn_t gfn,
+			      enum kvm_page_track_mode mode)
+{
+	struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
+
+	return kvm_slot_page_track_is_active(slot, gfn, mode);
+}
+
 void kvm_page_track_cleanup(struct kvm *kvm)
 {
 	struct kvm_page_track_notifier_head *head;
-- 
2.27.0