From 4293ddb788c1a98bdfa6479bcfd63ad5ce0a5ce6 Mon Sep 17 00:00:00 2001
From: Mingwei Zhang <mizhang@google.com>
Date: Mon, 2 Aug 2021 21:46:05 -0700
Subject: [PATCH] KVM: x86/mmu: Remove redundant spte present check in
mmu_set_spte
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>
Message-Id: <20210803044607.599629-2-mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.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 8568ae42e8675..2f6458bca65d8 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2776,17 +2776,13 @@ 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;
--
2.30.2