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| author | Ben Gardon <bgardon@google.com> | 2020-10-14 11:26:59 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-10-23 03:42:15 -0400 |
| commit | daa5b6c12337a0e6e269d022baa21b0549f507c3 (patch) | |
| tree | 9635671d4832b2cb86636ae880146bc2a032f4c5 /arch | |
| parent | 95fb5b0258b7bd2d540102771e31cfd76b72aa7b (diff) | |
| download | lwn-daa5b6c12337a0e6e269d022baa21b0549f507c3.tar.gz lwn-daa5b6c12337a0e6e269d022baa21b0549f507c3.zip | |
kvm: x86/mmu: Don't clear write flooding count for direct roots
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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 6a0941ccac34..7b52fa1f01b0 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -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, |