On Thu, 2010-04-15 at 11:05 +0300, Avi Kivity wrote: > On 04/15/2030 04:04 AM, Zhang, Yanmin wrote: > > > >> An even more accurate way to determine this is to check whether the > >> interrupt frame points back at the 'int $2' instruction. However we > >> plan to switch to a self-IPI method to inject the NMI, and I'm not sure > >> wether APIC NMIs are accepted on an instruction boundary or whether > >> there's some latency involved. > >> > > Yes. But the frame pointer checking seems a little complicated. > > > > An even bigger disadvantage is that it won't work with Sheng's patch, > self-NMIs are not synchronous. > > >>> trace_kvm_entry(vcpu->vcpu_id); > >>> + > >>> + percpu_write(current_vcpu, vcpu); > >>> kvm_x86_ops->run(vcpu); > >>> + percpu_write(current_vcpu, NULL); > >>> > >>> > >> If you move this around the 'int $2' instructions you will close the > >> race, as a stray NMI won't catch us updating the rip cache. But that > >> depends on whether self-IPI is accepted on the next instruction or not. > >> > > Right. The kernel part has dependency on the self-IPI implementation. > > I will move above percpu_write(current_vcpu, vcpu) (or a new wrapper > > function) > > just around 'int $2'. > > > > > > Or create a new function to inject the interrupt in x86.c. That will > reduce duplication between svm.c and vmx.c. 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.
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