Re: [Xen-devel] [PATCHv3 2/3] x86/fpu: Add a per-domain field to set the width of FIP/FDP

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.02.16 at 12:38, <david.vrabel@xxxxxxxxxx> wrote:
> On 25/02/16 11:24, Jan Beulich wrote:
>>>>> On 25.02.16 at 11:58, <david.vrabel@xxxxxxxxxx> wrote:
>>> @@ -261,7 +261,15 @@ void xsave(struct vcpu *v, uint64_t mask)
>>>                           "=m" (*ptr), \
>>>                           "a" (lmask), "d" (hmask), "D" (ptr))
>>>  
>>> -    if ( word_size <= 0 || !is_pv_32bit_vcpu(v) )
>>> +    if ( fip_width == 8 )
>>> +    {
>>> +        XSAVE("0x48,");
>>> +    }
>>> +    else if ( fip_width == 4 )
>>> +    {
>>> +        XSAVE("");
>>> +    }
>>> +    else
>> 
>> Both conditions would now better also check mask & XSTATE_FP,
>> since going these routes (and namely bypassing the FIP check, as
>> was done before) is fine when FP state is not being saved.
> 
> Is this what you mean?
> 
> --- a/xen/arch/x86/xstate.c
> +++ b/xen/arch/x86/xstate.c
> @@ -261,7 +261,7 @@ void xsave(struct vcpu *v, uint64_t mask)
>                           "=m" (*ptr), \
>                           "a" (lmask), "d" (hmask), "D" (ptr))
> 
> -    if ( fip_width == 8 )
> +    if ( fip_width == 8 || !(mask & XSTATE_FP) )
>      {
>          XSAVE("0x48,");
>      }

Oh, you're right, it's just one of the two that needs it.

Jan


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