Re: Bug: Xen panics with #UD in acpi_processor_idle()

[Rafal Wojtczuk <rafal@invisiblethingslab.com>]

On Mon, Nov 22, 2010 at 03:15:03PM +0000, Keir Fraser wrote:
> On 22/11/2010 13:02, "Rafal Wojtczuk" <rafal@invisiblethingslab.com> wrote:
> 
> > Hello,
> > 
> > There seems to be an issue with handling of
> > MSR_IA32_MISC_ENABLE_MONITOR_ENABLE bit in MSR_IA32_MISC_ENABLE. The effect
> > is that Xen panics because of #UD after trying to execute "monitor"
> > instruction. Most likely Xen does not bother to set this bit, leaving
> > it to BIOS. If I understand correctly, it is mere reliability issue, not
> > triggerable from any domain.
> 
> The issue appears to be be that we do not check for MWAIT support in CPUID,
> same as native Linux would do (the flag in MISC_ENABLE MSR also affects
> CPUID appropriately). Can you please try the attached patch? If it works I
> will apply it to all our trees.
Yes, with this patch the test machine boots fine.

Regards,
Rafal Wojtczuk