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

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Date:   Wed, 3 Jan 2018 14:32:28 +0800
From:   Quan Xu <quan.xu0@...il.com>
To:     Liran Alon <LIRAN.ALON@...CLE.COM>,
        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 2018/01/02 17:47, Liran Alon wrote:
>
>
> 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")
>
Reviewed-by: Quan Xu <quan.xu0@...il.com>