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

[Paolo Bonzini]

> 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.

Paolo