Re: [PATCH] Add MCE support to KVM

From: Anthony Liguori
Date: Tue Apr 21 2009 - 12:11:14 EST


Avi Kivity wrote:
Anthony Liguori wrote:
Avi Kivity wrote:

Then we would need to tell which read-only MSRs are setup writeable and which aren't...

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).

Why not introduce a new exit type for MSR reads/writes that aren't handled by the kernel? You just need a bit on the return that indicates whether to GPF because of an invalid MSR access.

KVM_SET_MSRs should be reserved for MSRs that are performance sensitive. Not all of them will be.


Right now everything in the vcpu is emulated in the kernel. Everything else is emulated either in the kernel (irqchip) or in userspace. This makes things easier to understand, and is more future friendly if more cpu features become virtualized by hardware.

Except cpuid, which is handled in userspace, sort of :-) I think the same arguments apply here too.

Regards,

Anthony Liguori
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