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

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Date:   Tue, 02 Jan 2018 11:47:10 +0200
From:   Liran Alon <LIRAN.ALON@...CLE.COM>
To:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
CC:     jmattson@...gle.com
Subject: Re: [PATCH] KVM: nVMX: remove unnecessary vmwrite from L2->L1 vmexit



On 02/01/18 00:58, Paolo Bonzini 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);
>

Reviewed-by: Liran Alon <liran.alon@...cle.com>

I would also add to commit message:
Fixes: 06a5524f091b ("KVM: nVMX: Fix posted intr delivery when vcpu is 
in guest mode")