Re: NMI Injection to Guest

[Gleb Natapov <gleb@redhat.com>]

On Sat, Jul 25, 2009 at 10:46:39PM +0200, Jiaqing Du wrote:
> Hi list,
> 
> I'm trying to extend OProfile to support guest profiling. One step of
> my work is to push an NMI to the guest(s) when a performance counter
> overflows. Please correct me if the following is not correct:
> 
> counter overflow --> NMI to host --> VM exit --> "int $2" to handle
> NMI on host --> ...   --> VM entry --> NMI to guest
> 
Correct except the last step (--> NMI to guest). Host nmi is not
propagated to guests.

> On the path between VM-exit and VM-entry, I want to push an NMI to the
> guest. I tried to put the following code on the path, but never
> succeeded. Various wired things happened, such as KVM hangs, guest
> kernel oops, and host hangs. I tried both code with Linux 2.6.30 and
> version 88.
> 
> if (vmx_nmi_allowed())  { vmx_inject_nmi(); }
> 
> Any suggestions? Where is the right place to push an NMI and what are
> the necessary checks?
Call kvm_inject_nmi(vcpu). And don't forget to vcpu_load(vcpu) before
doing it. See kvm_vcpu_ioctl_nmi().

--
			Gleb.