Re: [PATCH 1/2] KVM: SVM: Fix NMI path when NMI happens in guest mode

Roedel, Joerg
2011-01-14T13:36:18Z

On Thu, Jan 13, 2011 at 02:27:00PM -0500, Avi Kivity wrote:
> On 01/13/2011 05:51 PM, Roedel, Joerg wrote:
> > I also had a look at entry_64.S. The save_paranoid could not be the
> > cause because MSR_GS_BASE is already negative at this point. But the
> > re-schedule condition check at the end of the NMI handler code could
> > also not be the cause because the NMI happens while preemption (and
> > interrupts) are disabled (a re-schedule should also trigger
> > preempt-notifiers and restore KERNEL_GS_BASE).
> >
>
> I have it:

Cool, good catch. Thanks :)

The only use of load_gs_index in svm is the vcpu_put function. It is
sufficient to just swap the KERNEL_GS_BASE wrmsr and the load_gs_index
function calls in there to be safe.

Joerg

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