Re: Oops for sale

Avi Kivity
2008-06-09T16:33:13Z

> Log attached. Scanning it and having a brief look at the source code
> makes me suspect it could be a flags update triggering this: Due to
> 64bit xen guest kernels running in ring3 xenner may just flip the user
> bit (off->on) in the page table handler, which is a unusual operation I
> guess ...
>

The unshadow-on-userspace-access heuristic is broken. Since it is also
bad for Xenner, try removing the following lines:

spte |= PT_WRITABLE_MASK;
if (user_fault) {
mmu_unshadow(vcpu->kvm, gfn);
goto unshadowed;
}

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.