Re: [Xen-devel] [PATCH 15/19] x86/vmce: emulate MSR_IA32_MCG_EXT_CTL

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

On 02/23/17 00:53 -0700, Jan Beulich wrote:
> >>> On 23.02.17 at 05:26, <haozhong.zhang@xxxxxxxxx> wrote:
> > On 02/22/17 08:36 -0700, Jan Beulich wrote:
> >> >>> On 17.02.17 at 07:39, <haozhong.zhang@xxxxxxxxx> wrote:
> >> All of this said - is this really a per-vCPU property, instead of a
> >> per-domain one?
> > 
> > Per-vCPU. At least it can be set in the per-CPU way. Patch 16, which
> > implements the vLMCE injection, checks this per-vcpu flag when
> > injecting vMCE. If the flag is cleared, vMCE (w/ MCG_STATUS_LMCE
> > removed) will be broadcast to all vcpus.
> 
> You answer my question based on the mechanics of your patches,
> but the question was from a conceptual / architectural perspective.
> 

LMCE can be enabled by SW in the per-CPU way on the real hardware,
i.e. it can be enabled on some CPUs while disabled on others.
lmce_enabled is to track whether guest SW enables LMCE on a vcpu, so
it should be a per-vcpu property.

Haozhong


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