Re: [PATCH v2 06/10] KVM: VMX: Don't invalidate hv_tlb_eptp if the new EPTP matches

[Vitaly Kuznetsov]

Sean Christopherson <sean.j.christopherson@xxxxxxxxx> writes:

> Don't invalidate the common EPTP, and thus trigger rechecking of EPTPs
> across all vCPUs, if the new EPTP matches the old/common EPTP.  In all
> likelihood this is a meaningless optimization, but there are (uncommon)
> scenarios where KVM can reload the same EPTP.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
>  arch/x86/kvm/vmx/vmx.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 4dfde8b64750..e6569bafacdc 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -3043,7 +3043,8 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, unsigned long pgd,
>  		if (kvm_x86_ops.tlb_remote_flush) {
>  			spin_lock(&to_kvm_vmx(kvm)->ept_pointer_lock);
>  			to_vmx(vcpu)->ept_pointer = eptp;
> -			to_kvm_vmx(kvm)->hv_tlb_eptp = INVALID_PAGE;
> +			if (eptp != to_kvm_vmx(kvm)->hv_tlb_eptp)
> +				to_kvm_vmx(kvm)->hv_tlb_eptp = INVALID_PAGE;
>  			spin_unlock(&to_kvm_vmx(kvm)->ept_pointer_lock);
>  		}

Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>

-- 
Vitaly