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.
