Re: [Xen-devel] [PATCH] pv/pvh: disable MTRR feature on cpuid for Dom0

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On 13/12/13 12:28, Jan Beulich wrote:
>>>> On 12.12.13 at 17:52, Roger Pau Monne <roger.pau@xxxxxxxxxx> wrote:
>> MTRR is not available for PV/PVH Dom0, so prevent cpuid from
>> reporting it as an available feature.
> 
> Some misunderstanding perhaps? PV certainly has MTRR support for
> Dom0 - see XENPF_*_memtype.

OK, my bad, I was looking for a PV implementation of struct mtrr_ops in
the pvops kernel, but Linux pvops doesn't use MTRR at all, also none of
the XENPF_*_memtype ops seem to be used.

>
>> --- a/xen/arch/x86/traps.c
>> +++ b/xen/arch/x86/traps.c
>> @@ -796,6 +796,7 @@ void pv_cpuid(struct cpu_user_regs *regs)
>>          __clear_bit(X86_FEATURE_DS, &d);
>>          __clear_bit(X86_FEATURE_ACC, &d);
>>          __clear_bit(X86_FEATURE_PBE, &d);
>> +        __clear_bit(X86_FEATURE_MTRR, &d);
> 
> Thus clearing this flag should be limited to PVH.

Will resend now with this fixed, thanks.

Roger.


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