linux-kernel - [PATCH V4 5/15] KVM/MMU: Move tlb flush in kvm_set_pte_rmapp() to kvm_mmu_notifier_change

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Message-Id: <20181013145406.4911-6-Tianyu.Lan@microsoft.com>
Date:   Sat, 13 Oct 2018 22:53:56 +0800
From:   lantianyu1986@...il.com
To:     unlisted-recipients:; (no To-header on input)
Cc:     Lan Tianyu <Tianyu.Lan@...rosoft.com>, kys@...rosoft.com,
        haiyangz@...rosoft.com, sthemmin@...rosoft.com, tglx@...utronix.de,
        mingo@...hat.com, hpa@...or.com, x86@...nel.org,
        pbonzini@...hat.com, rkrcmar@...hat.com,
        devel@...uxdriverproject.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, michael.h.kelley@...rosoft.com,
        vkuznets@...hat.com
Subject: [PATCH V4 5/15] KVM/MMU: Move tlb flush in kvm_set_pte_rmapp() to kvm_mmu_notifier_change_pte()

From: Lan Tianyu <Tianyu.Lan@...rosoft.com>

This patch is to move tlb flush in kvm_set_pte_rmapp() to
kvm_mmu_notifier_change_pte() in order to avoid redundant tlb flush.

Signed-off-by: Lan Tianyu <Tianyu.Lan@...rosoft.com>
---
 arch/x86/kvm/mmu.c  | 8 ++------
 virt/kvm/kvm_main.c | 5 ++++-
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index fd24a4dc45e9..5d3a180c57e2 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1781,10 +1781,7 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 		}
 	}
 
-	if (need_flush)
-		kvm_flush_remote_tlbs(kvm);
-
-	return 0;
+	return need_flush;
 }
 
 struct slot_rmap_walk_iterator {
@@ -1920,8 +1917,7 @@ int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end)
 
 int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
 {
-	kvm_handle_hva(kvm, hva, (unsigned long)&pte, kvm_set_pte_rmapp);
-	return 0;
+	return kvm_handle_hva(kvm, hva, (unsigned long)&pte, kvm_set_pte_rmapp);
 }
 
 static int kvm_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index acc951cc2663..bd026d74541e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -354,7 +354,10 @@ static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
 	idx = srcu_read_lock(&kvm->srcu);
 	spin_lock(&kvm->mmu_lock);
 	kvm->mmu_notifier_seq++;
-	kvm_set_spte_hva(kvm, address, pte);
+
+	if (kvm_set_spte_hva(kvm, address, pte))
+		kvm_flush_remote_tlbs(kvm);
+
 	spin_unlock(&kvm->mmu_lock);
 	srcu_read_unlock(&kvm->srcu, idx);
 }
-- 
2.14.4