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KVM: x86/mmu: Skip no-op changes in TDP MMU functions 

Skip setting SPTEs if no change is expected.

Reviewed-by: Peter Feiner <pfeiner@google.com>
Signed-off-by: Ben Gardon <bgardon@google.com>

Message-Id: <20210202185734.1680553-16-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ben Gardon 2021-02-02 10:57:21 -08:00 committed by Paolo Bonzini
parent 1af4a96025
commit 0f99ee2c7a
1 changed files with 4 additions and 2 deletions
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6
arch/x86/kvm/mmu/tdp_mmu.c
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@ -888,7 +888,8 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
continue;
if (!is_shadow_present_pte(iter.old_spte) ||
!is_last_spte(iter.old_spte, iter.level))
!is_last_spte(iter.old_spte, iter.level) ||
!(iter.old_spte & PT_WRITABLE_MASK))
continue;
new_spte = iter.old_spte & ~PT_WRITABLE_MASK;
@ -1065,7 +1066,8 @@ static bool set_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
if (tdp_mmu_iter_cond_resched(kvm, &iter, false))
continue;
if (!is_shadow_present_pte(iter.old_spte))
if (!is_shadow_present_pte(iter.old_spte) ||
iter.old_spte & shadow_dirty_mask)
continue;
new_spte = iter.old_spte | shadow_dirty_mask;