linux-kernel - Re: [PATCH] KVM: nVMX: Fix the NMI IDT-vectoring info handling

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Message-ID: <CANRm+Czu6WKQdYX820VeCBEZrie1Uyo2hL+RSiwwdKpwCPQEcA@mail.gmail.com>
Date:   Thu, 22 Sep 2016 17:45:38 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kvm <kvm@...r.kernel.org>, Wanpeng Li <wanpeng.li@...mail.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        Bandan Das <bsd@...hat.com>
Subject: Re: [PATCH] KVM: nVMX: Fix the NMI IDT-vectoring info handling

2016-09-22 17:37 GMT+08:00 Paolo Bonzini <pbonzini@...hat.com>:
>
>
> On 22/09/2016 05:34, Wanpeng Li wrote:
>> -     if (vmx->rmode.vm86_active) {
>> -             if (kvm_inject_realmode_interrupt(vcpu, NMI_VECTOR, 0) != EMULATE_DONE)
>> -                     kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
>> -             return;
>> +             ++vcpu->stat.nmi_injections;
>> +             vmx->nmi_known_unmasked = false;
>> +             if (vmx->rmode.vm86_active) {
>> +                     if (kvm_inject_realmode_interrupt(vcpu, NMI_VECTOR, 0) != EMULATE_DONE)
>> +                             kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
>> +                     return;
>> +             }
>>       }
>>       vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
>>                       INTR_TYPE_NMI_INTR | INTR_INFO_VALID_MASK | NMI_VECTOR);
>
> Hi,
>
> the patch is mostly okay but the "if (vmx->rmode.vm86_active)" part
> should be done also if the VCPU is in guest mode.  See
> vmx_queue_exception for a similar example.

Thanks for pointing out. :)

>
> I would like to know which processors lack virtual NMI support.  I'd
> rather rip that code out...

At least the Sandy Bridge server on my hand supports Virtual NMIs, I
don't have machine older than this.

Regards,
Wanpeng Li