Re: [Qemu-devel] [PATCH v2 1/5] i386: Add support for IA32_PRED_CMD and IA32_ARCH_CAPABILITIES MSRs

[Robert Hoo]

On Thu, 2018-06-28 at 16:20 +0200, Paolo Bonzini wrote:
> On 28/06/2018 11:25, Robert Hoo wrote:
> >>> +    uint64_t pred_cmd;
> >>> +    uint64_t arch_capabilities;
> >> What's the purpose of those CPUX86State fields, if the migration
> >> sections were removed in v2?
> >>
> > Thanks Eduardo. Going to clean up in v3. Any more comments, regarding
> > other patches?
> 
> Yes - something like arch_capabilities must stay, as it will be filled
> in with "CPUID-like" feature bits that are actually visible to the guest
> via the MSR.
> 
> However, I suggest adding it to the FeatureWord enum, since everything
> that handles FeatureWord applies to this new kind of MSR as well.
> Currently FeatureWord is only for CPUID leaves, but it doesn't have to
> be like that.
> 
I think this will be changing struct FeatureWordInfo, which is designed
for cpuid enumerations. You must not want to do that. May I know more
details about your thought?

And, if I implemented ARCH_CAPABILITIES-bits features in FeatureWord,
then no necessity of having it in kvm_msr_entries, right?
> Paolo