RE: [Xen-devel] [PATCH] X86: cpuid faulting feature enable

["Liu, Jinsong" <jinsong.liu@xxxxxxxxx>]

Keir Fraser wrote:
> On 01/07/2011 18:48, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:
> 
>>> Down to a particular stepping? That surely doesn't make sense for
>>> anything but your own experimenting.
>> 
>> Yes, it's some ugly.
>> Currently cpuid faulting is not a architecturally commited feature,
>> and, some other Intel processors (which do not has cpuid faulting
>> feature) also has 0xceh MSR. Hence I use current way for safe.
>> However, I marked it as FIXME to update in the future accordingly.
> 
> But Intel's own supporting document states that bit 31 of the
> PLATFORM_INFO MSR should be sufficient to identify the cpuid faulting
> feature. Do you really need the stepping check as well? Could you
> just do a rdmsr_safe read-and-check of PLATFORM_INFO_MSR[31] instead?
> 
> It would be okay for other Intel CPUs to have MSR 0xce, so long as
> they don't set bit 31...
> 
>  -- Keir

That's good. It does formally state.
We can move family/model/stepping now.

Thanks,
Jinsong
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