Re: [PATCH] KVM: SVM: vNMI pending bit is V_NMI_PENDING_MASK not V_NMI_BLOCKING_MASK

[Maciej S. Szmigiero]

On 1.06.2023 20:04, Sean Christopherson wrote:
> On Thu, Jun 01, 2023, Maciej S. Szmigiero wrote:
> > On 19.05.2023 17:51, Sean Christopherson wrote:
> > > On Fri, May 19, 2023, Maciej S. Szmigiero wrote:
> > > > From: "Maciej S. Szmigiero" <maciej.szmigiero@xxxxxxxxxx>
> > > >
> > > > While testing Hyper-V enabled Windows Server 2019 guests on Zen4 hardware
> > > > I noticed that with vCPU count large enough (> 16) they sometimes froze at
> > > > boot.
> > > > With vCPU count of 64 they never booted successfully - suggesting some kind
> > > > of a race condition.
> > > >
> > > > Since adding "vnmi=0" module parameter made these guests boot successfully
> > > > it was clear that the problem is most likely (v)NMI-related.
> > > >
> > > > Running kvm-unit-tests quickly showed failing NMI-related tests cases, like
> > > > "multiple nmi" and "pending nmi" from apic-split, x2apic and xapic tests
> > > > and the NMI parts of eventinj test.
> > > >
> > > > The issue was that once one NMI was being serviced no other NMI was allowed
> > > > to be set pending (NMI limit = 0), which was traced to
> > > > svm_is_vnmi_pending() wrongly testing for the "NMI blocked" flag rather
> > > > than for the "NMI pending" flag.
> > > >
> > > > Fix this by testing for the right flag in svm_is_vnmi_pending().
> > > > Once this is done, the NMI-related kvm-unit-tests pass successfully and
> > > > the Windows guest no longer freezes at boot.
> > > >
> > > > Fixes: fa4c027a7956 ("KVM: x86: Add support for SVM's Virtual NMI")
> > > > Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
> > >
> > > Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> >
> > I can't see this in kvm/kvm.git trees or the kvm-x86 ones on GitHub -
> > is this patch planned to be picked up for -rc5 soon?
> >
> > Technically, just knowing the final commit id would be sufficit for my
> > purposes.
>
> If Paolo doesn't pick it up by tomorrow, I'll apply it and send a fixes pull
> request for -rc5.

Thanks Sean.