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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.02.17 at 09:54, <haozhong.zhang@xxxxxxxxx> wrote:
> 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.

Good point.

Jan


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