Re: [Xen-devel] [V3 PATCH 7/9] x86/hvm: pkeys, add pkeys support for guest_walk_tables

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.12.15 at 19:19, <george.dunlap@xxxxxxxxxx> wrote:
> On 07/12/15 09:16, Huaitong Han wrote:
>> +    if ( likely(!pte_pkeys) )
>> +        return 0;
>> +
>> +    /* Update vcpu xsave area */
>> +    fpu_xsave(vcpu);
> 
> Is there a reason you're calling fpu_xsave() directly here, rather than
> just calling vcpu_save_fpu()?  That saves you actually doing the xsave
> if the fpu hasn't been modified since the last time you read it.

I've already said on an earlier version that wholesale saving of the
entire XSAVE state is wrong here. It should just be the single piece
that we're actually interested in, and it quite likely shouldn't go into
struct vcpu (but e.g. into a local buffer).

Jan


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