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

bugzilla-daemon
2020-01-16T01:36:31Z

--- Comment #4 from kernel@najdan.com ---
(In reply to derek from comment #3)
> 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

Sean,
I'm not familiar with rebuilding the kernel, nor applying a patch but I'm
working on it right now so I can provide feedback.

> 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
>
> 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.

> 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
>
> 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.

Derek,

Thanks for the update.

I'm still curious about the hypervisor CPU model you have.

On Windows I did exprecience a different behavior though.
The OS did boot but the spice/VNC screen did freeze randomly.
One of my windows VM did end up being corrupted as an update ehich tried to
install just failed miserably.

Anyways, I will try to provide debug details asap from the patch that Sean
provided...

To be continued ...