Re: [PATCH V3] perf & kvm: Enhance perf to collect KVM guest os statisticsfrom host side

[Avi Kivity]

On 04/15/2010 12:04 PM, oerg Roedel wrote:
> On Mon, Apr 15, 2030 at 04:57:38PM +0800, Zhang, Yanmin wrote:
>
>    
> > I checked svm.c and it seems svm.c doesn't trigger a NMI to host if the NMI
> > happens in guest os. In addition, svm_complete_interrupts is called after
> > interrupt is enabled.
> >      
> Yes. The NMI is held pending by the hardware until the STGI instruction
> is executed.
> And for nested svm the svm_complete_interrupts function needs to be
> executed after the nested exit handling. Therefore it is done late on
> svm.
>    

So, we'd need something like the following:

   if (exit == NMI)
       __get_cpu_var(nmi_vcpu) = vcpu;

   stgi();

   if (exit == NMI) {
       while (!nmi_handled())
           cpu_relax();
       __get_cpu_var(nmi_vcpu) = NULL;
   }

and no code sharing betweem vmx and svm.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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