Hi all,
What about using vmx_inject_nmi(vcpu) to inject the NMIs into the
guest, when we are sure about the vcpu on which the NMI is to be
injected.
Nipun
On Mon, Jul 27, 2009 at 12:55 AM, Jiaqing Du <jiaqing@xxxxxxxxx> wrote:
>
> Hi Gleb,
>
> Thanks for your reply.
>
> 2009/7/26 Gleb Natapov <gleb@xxxxxxxxxx>:
> > 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.
>
> Yes. I need to add some code to propagate host NMI 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().
>
> Based on the code with Linux 2.6.30, what kvm_inject_nmi(vcpu) does is
> just set vcpu->arch.nmi_pending to 1. kvm_vcpu_ioctl_nmi() puts
> vcpu_load() before the setting and vcpu_put() after it.
>
> I need to push host NMI to guests between a VM-exit and a VM-entry
> after that. The VM-exit is due to an NMI caused by performance counter
> overflow. The following code with vcpu_enter_guest(), which is
> surrounded by a vcpu_load() and vcpu_put(), checks this
> vcpu->arch.nmi_pending and other related flags to decide whether an
> NMI should be pushed to guests.
>
> if (vcpu->arch.exception.pending)
> __queue_exception(vcpu);
> else if (irqchip_in_kernel(vcpu->kvm))
> kvm_x86_ops->inject_pending_irq(vcpu);
> else
> kvm_x86_ops->inject_pending_vectors(vcpu, kvm_run);
>
> What I did is given below:
>
> 3097 static int vcpu_enter_guest(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
> 3098 {
> ... ...
>
> 3156 if (kvm_vm_exit_on_cnt_overflow) {
> 3157 vcpu->arch.nmi_pending = 1;
> 3158 }
> 3159
> 3160 if (vcpu->arch.exception.pending)
> 3161 __queue_exception(vcpu);
> 3162 else if (irqchip_in_kernel(vcpu->kvm))
> 3163 kvm_x86_ops->inject_pending_irq(vcpu);
> 3164 else
> 3165 kvm_x86_ops->inject_pending_vectors(vcpu, kvm_run);
>
> ... ....
> 3236 }
>
> In vcpu_enter_guest(), before this part of code is reached,
> vcpu->arch.nmi_pending is set to 1 if the VM-exit is due to
> performance counter overflow. Still, no NMIs are seen by the guests. I
> also tried to put this "vcpu->arch.nmi_pending = 1;" somewhere else on
> the path between a VM-exit and VM-entry, it does not seem to work
> neither. Only vmx_inject_nmi() manages to push NMIs to guests, but
> without right sanity checks, it causes various wired host and guest
> behaviors.
>
> To inject NMIs on the path between a VM-exit and VM-entry, what's to try next?
>
> >
> > --
> > Gleb.
> >
>
> Thanks,
> Jiaqing
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