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kvm: x86/mmu: Don't clear write flooding count for direct roots

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Direct roots don't have a write flooding count because the guest can't
affect that paging structure. Thus there's no need to clear the write
flooding count on a fast CR3 switch for direct roots.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
	https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538

Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20201014182700.2888246-20-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ben Gardon 2020-10-14 11:26:59 -07:00 committed by Paolo Bonzini
parent 95fb5b0258
commit daa5b6c123
1 changed files with 7 additions and 1 deletions
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8
arch/x86/kvm/mmu/mmu.c
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@ -3892,7 +3892,13 @@ static void __kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd,
*/
vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY);
__clear_sp_write_flooding_count(to_shadow_page(vcpu->arch.mmu->root_hpa));
/*
* If this is a direct root page, it doesn't have a write flooding
* count. Otherwise, clear the write flooding count.
*/
if (!new_role.direct)
__clear_sp_write_flooding_count(
to_shadow_page(vcpu->arch.mmu->root_hpa));
}
void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd, bool skip_tlb_flush,