SIGILL in grub in guest on 4365

["Gregory Haskins" <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>]

Hi All,
  New to the list and project...hoping to make a meaningful contribution here someday :)

I am in the process of coming up to speed on the KVM project (very cool BTW).  I found that it was extremely simple to get setup and running.  During the course of setting it up, I found an issue running a SUSE Linux Enterprise Desktop 10 (x86_64) guest.  Basically, if you try to run GRUB, the grub process dies immediately as it takes an illegal instruction (SIGILL) signal.  Non-symbol stack traces indicate it was in the sync() call in libc.  I have worked around this temporarily by installing LILO under rescue mode...but I figured what better way to learn the code than to try to debug and fix this issue.

My assumption is that an illegal-opcode will cause either a vm-exit or an illegal-opcode exception down to the host.  This in turn would cause either the KVM_RUN ioctl to return (presumably with an EXCEPTION reason) or a signal to be delivered to QEMU.  Problem is, I am fairly stumped at this point trying to prove this is true.

So my questions are: 

1) Is this how illegal-op would be handled, or would that stay entirely in the domain of the guest?  

2) If they do cause a host exception/exit, what is that path that would handle this?

I put breakpoints in QEMU in all the obvious places (e.g. looking for VM-Exits in kvm_run(), host-2-guest exception generation points, and/or signal handlers).  I have also straced QEMU and it doesn't appear to be taking any signals other than SIGIO.  My next step will be to start sprinkling printfs in the QEMU/KVM code and/or debugging/LTT'ing the kernel, but I figured I would ping the group for suggestions first.  Any pointers out there?

Another possibility is that the guest is not generating a real illegal-op and the bug is that QEMU/KVM is accidentally injecting the exception condition (due to corruption, etc) and that explains why I cant seem to find it being explicitly handled.  Its too early to say right now, of course.

Thanks!
-Greg

PS: Other than the grub issue, I have been successfully  hosting a 64 bit SLED guest on KVM for days now, so we are pretty close to being able to add it to your list of working guests.


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