[Bug 218684] CPU soft lockups in KVM VMs on kernel 6.x after switching hypervisor from C8S to C9S

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=218684

Igor Mammedov (imammedo@redhat.com) changed:

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--- Comment #5 from Igor Mammedov (imammedo@redhat.com) ---
(In reply to Frantisek Sumsal from comment #4)
> (In reply to Sean Christopherson from comment #3)
> > Given that 6.7 is still broken, my money is on commit d02c357e5bfa ("KVM:
> > x86/mmu: Retry fault before acquiring mmu_lock if mapping is changing"). 
> > Ugh, which I neglected to mark for stable.
> > 
> > Note, if that's indeed what's to blame, there's also a bug in the kernel's
> > preemption model logic that is contributing to the problems.
> > https://lore.kernel.org/all/20240110214723.695930-1-seanjc@google.com
> 
> You're absolutely right. I took the C9S kernel RPM (5.14.0-436), slapped
> d02c357e5bfa on top of it, and after running the same tests as in previous
> cases all the soft lockups seem to be magically gone. Thanks a lot!
> 
> I'll run a couple more tests and if they pass I'll go ahead and sum this up
> in a RHEL report, so the necessary patches make it to C9S/RHEL9.

Thanks for reporting it upstream, as for C9S it should be fixed in
kernel-5.14.0-444.el9
https://issues.redhat.com/browse/RHEL-17714

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