linux-kernel - Re: [PATCH] KVM: nVMX: remove unnecessary vmwrite from L2->L1 vmexit

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Message-ID: <CALMp9eSdXWqVhTfWMWSpo2+ZXAUFtPzA0QW+JtSoaWH3FCDvPQ@mail.gmail.com>
Date:   Mon, 1 Jan 2018 16:45:24 -0800
From:   Jim Mattson <jmattson@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, kvm list <kvm@...r.kernel.org>
Subject: Re: [PATCH] KVM: nVMX: remove unnecessary vmwrite from L2->L1 vmexit

Reviewed-by: Jim Mattson <jmattson@...gle.com>

On Mon, Jan 1, 2018 at 2:58 PM, Paolo Bonzini <pbonzini@...hat.com> wrote:
> The POSTED_INTR_NV field is constant (though it differs between the vmcs01 and
> vmcs02), there is no need to reload it on vmexit to L1.
>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
>  arch/x86/kvm/vmx.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index e6223fe8faa1..1e184830a295 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -11610,9 +11610,6 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
>                  */
>                 vmx_flush_tlb(vcpu, true);
>         }
> -       /* Restore posted intr vector. */
> -       if (nested_cpu_has_posted_intr(vmcs12))
> -               vmcs_write16(POSTED_INTR_NV, POSTED_INTR_VECTOR);
>
>         vmcs_write32(GUEST_SYSENTER_CS, vmcs12->host_ia32_sysenter_cs);
>         vmcs_writel(GUEST_SYSENTER_ESP, vmcs12->host_ia32_sysenter_esp);
> --
> 1.8.3.1
>