[Bug 206215] QEMU guest crash due to random 'general protection fault' since kernel 5.2.5 on i7-3517UE

bugzilla-daemon
2020-01-16T15:38:59Z

--- Comment #5 from Sean Christopherson (sean.j.christopherson@intel.com) ---
On Wed, Jan 15, 2020 at 08:08:32PM -0500, Derek Yerger wrote:
> On 1/15/20 4:52 PM, Sean Christopherson wrote:
> >+cc Derek, who is hitting the same thing.
> >
> >On Wed, Jan 15, 2020 at 09:18:56PM +0000,
> bugzilla-daemon@bugzilla.kernel.org wrote:
> >>https://bugzilla.kernel.org/show_bug.cgi?id=206215
> >*snip*
> >that's a big smoking gun pointing at commit ca7e6b286333 ("KVM: X86: Fix
> >fpu state crash in kvm guest"), which is commit e751732486eb upstream.
> >
> >1. Can you verify reverting ca7e6b286333 (or e751732486eb in upstream)
> > solves the issue?
> >
> >2. Assuming the answer is yes, on a buggy kernel, can you run with the
> > attached patch to try get debug info?
> I did these out of order since I had 5.3.11 built with the patch, ready to
> go for weeks now, waiting for an opportunity to test.
>
> Win10 guest immediately BSOD'ed with:
>
> WARNING: CPU: 2 PID: 9296 at include/linux/thread_info.h:55
> kernel_fpu_begin+0x6b/0xc0

Can you provide the full stack trace of the WARN? I'm hoping that will
provide a hint as to what's going wrong.

> Then stashed the patch, reverted ca7e6b286333, compile, reboot.
>
> Guest is running stable now on 5.3.11. Did test my CAD under the guest, did
> not experience the crashes that had me stuck at 5.1.