Re: general protection fault in vmx_vcpu_run (2)

[Dmitry Vyukov]

On Wed, Feb 24, 2021 at 7:08 PM 'Sean Christopherson' via
syzkaller-bugs <syzkaller-bugs@xxxxxxxxxxxxxxxx> wrote:
>
> On Wed, Feb 24, 2021, Borislav Petkov wrote:
> > Hi Dmitry,
> >
> > On Wed, Feb 24, 2021 at 06:12:57PM +0100, Dmitry Vyukov wrote:
> > > Looking at the bisection log, the bisection was distracted by something else.
> >
> > Meaning the bisection result:
> >
> > 167dcfc08b0b ("x86/mm: Increase pgt_buf size for 5-level page tables")
> >
> > is bogus?
>
> Ya, looks 100% bogus.
>
> > > You can always find the original reported issue over the dashboard link:
> > > https://syzkaller.appspot.com/bug?extid=42a71c84ef04577f1aef
> > > or on lore:
> > > https://lore.kernel.org/lkml/0000000000007ff56205ba985b60@xxxxxxxxxx/
> >
> > Ok, so this looks like this is trying to run kvm ioctls *in* a guest,
> > i.e., nested. Right?
>
> Yep.  I tried to run the reproducer yesterday, but the kernel config wouldn't
> boot my VM.  I haven't had time to dig in.  Anyways, I think you can safely
> assume this is a KVM issue unless more data comes along that says otherwise.

Interesting. What happens? Does the kernel crash? Userspace crash?
Rootfs is not mounted? Or something else?