Re: [PATCH] Add MCE support to KVM

[Avi Kivity]

Huang Ying wrote:
> > I'm okay with an ioctl to setup MCE, but just make sure userspace has 
> > all the information to know what the kernel can do rather than the 
> > try-and-see-if-it-works approach.  We can publish this information via 
> > KVM_CAP things, or via another ioctl (see KVM_GET_SUPPORTED_CPUID2 for 
> > an example).
> >     
>
> Yes. MCE support should be published by KVM_CAP_MCE and other features
> can be published via reading the default value of MSR_IA32_MCG_CAP.
>   

A problem with this is that you can only read an MSR after a vcpu has 
been created.  But if you're writing a program to detect what features 
are available (for example, when checking features common to a migration 
pool), you don't want to create a vpcu (you could, but it's hacky).

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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