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From: Mingwei Zhang <mizhang@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Ben Gardon <bgardon@google.com>,
	David Matlack <dmatlack@google.com>,
	Mingwei Zhang <mizhang@google.com>,
	Jing Zhang <jingzhangos@google.com>
Subject: [PATCH v4 1/3] KVM: x86/mmu: Remove redundant spte present check in mmu_set_spte
Date: Mon,  2 Aug 2021 21:46:05 -0700	[thread overview]
Message-ID: <20210803044607.599629-2-mizhang@google.com> (raw)
In-Reply-To: <20210803044607.599629-1-mizhang@google.com>

Drop an unnecessary is_shadow_present_pte() check when updating the rmaps
after installing a non-MMIO SPTE.  set_spte() is used only to create
shadow-present SPTEs, e.g. MMIO SPTEs are handled early on, mmu_set_spte()
runs with mmu_lock held for write, i.e. the SPTE can't be zapped between
writing the SPTE and updating the rmaps.

Opportunistically combine the "new SPTE" logic for large pages and rmaps.

No functional change intended.

Suggested-by: Ben Gardon <bgardon@google.com>

Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
---
 arch/x86/kvm/mmu/mmu.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index a8cdfd8d45c4..f614e9df3c3b 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2734,17 +2734,13 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 
 	pgprintk("%s: setting spte %llx\n", __func__, *sptep);
 	trace_kvm_mmu_set_spte(level, gfn, sptep);
-	if (!was_rmapped && is_large_pte(*sptep))
-		++vcpu->kvm->stat.lpages;
 
-	if (is_shadow_present_pte(*sptep)) {
-		if (!was_rmapped) {
-			rmap_count = rmap_add(vcpu, sptep, gfn);
-			if (rmap_count > vcpu->kvm->stat.max_mmu_rmap_size)
-				vcpu->kvm->stat.max_mmu_rmap_size = rmap_count;
-			if (rmap_count > RMAP_RECYCLE_THRESHOLD)
-				rmap_recycle(vcpu, sptep, gfn);
-		}
+	if (!was_rmapped) {
+		if (is_large_pte(*sptep))
+			++vcpu->kvm->stat.lpages;
+		rmap_count = rmap_add(vcpu, sptep, gfn);
+		if (rmap_count > RMAP_RECYCLE_THRESHOLD)
+			rmap_recycle(vcpu, sptep, gfn);
 	}
 
 	return ret;
-- 
2.32.0.554.ge1b32706d8-goog


  reply	other threads:[~2021-08-03  4:46 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-03  4:46 [PATCH v4 0/3] Add detailed page size stats in KVM stats Mingwei Zhang
2021-08-03  4:46 ` Mingwei Zhang [this message]
2021-08-03  4:46 ` [PATCH v4 2/3] KVM: x86/mmu: Avoid collision with !PRESENT SPTEs in TDP MMU lpage stats Mingwei Zhang
2021-08-03  4:46 ` [PATCH v4 3/3] KVM: x86/mmu: Add detailed page size stats Mingwei Zhang
2021-08-09 22:26   ` Jim Mattson
2021-08-09 23:39     ` Mingwei Zhang
2021-08-10  0:01       ` Mingwei Zhang
2021-08-10 23:22         ` Peter Xu
2021-08-11  1:06           ` Mingwei Zhang
2021-08-11 13:12             ` Peter Xu
2021-08-12 17:44               ` Mingwei Zhang
2021-08-11 11:36   ` Paolo Bonzini

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