Re: [Xen-devel] your IRC thread regarding a crash in __sanitize_i387_state()

[Matt Wilson <msw@xxxxxxxxxx>]

On Thu, Jun 27, 2013 at 07:55:57AM +0100, Jan Beulich wrote:
> Considering that you see XSAVE disabled in CPUID, is it possible that
> this is being enforced via CPUID masking or some such?

Yup, I'm pretty sure this was a config problem with masking.

> If so, is the CPU supporting XSAVEOPT by chance? That CPUID flag
> would then also need to be masked, or else the kernel would get
> misled calling __sanitize_i387_state() from sanitize_i387_state()
> despite there not being anything to sanitize (which matches the
> fault address in the pointed to stack dump being 512 bytes ahead
> of %rbx).

xsaveopt was listed in /proc/cpuinfo. I didn't check the results of
the cpuid instruction, but I'm guessing that it wasn't appropriately
masked.

This makes sense. Thanks for following up!

--msw

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