Re: [Qemu-devel] [SeaBIOS] [PATCH v3] fw/msr_feature_control: add support to set MSR_IA32_FEATURE_CONTROL

[Haozhong Zhang]

Hi Ashok,

On 07/06/16 02:18, Paolo Bonzini wrote:
> > I forgot to restore MSR_IA32_FEATURE_CONTROL in the resume path, and
> > MSR_IA32_FEATURE_CONTROL is zero after S3 resume.
> 
> This is a bug.  Sorry Laszlo. :)
> 
> > Not restore MSR_IA32_FEATURE_CONTROL during S3 resume does not affect
> > at least Linux guest (tested 4.5). Current QEMU may advise the guest
> > firmware to set bit 20 (for LMCE), bit 2 (for VMX) and bit 0 (lock
> > bit).
> > - For LMCE, Linux only checks bit 20 and bit 0 at boot time and then
> >   keeps using the result even after resume.
> 
> On real hardware, LMCE would not be enabled after resume.  I'm not
> sure what would happen, but it wouldn't be good.

Could you help to check if the LMCE bit in MSR_IA32_FEATURE_CONTROL is
set after S3 resume on the real hardware?

Thanks,
Haozhong