On Wed, Jun 01, 2016 at 09:50:10AM -0600, Jan Beulich wrote:
> >>> On 01.06.16 at 17:35, <andrew.coop...@citrix.com> wrote:
> > On 01/06/16 16:06, Jan Beulich wrote:
> >> @@ -3440,42 +3440,24 @@ void hvm_cpuid(unsigned int input, unsig
> >> *eax = *ebx = *ecx = *edx = 0;
> >> break;
> >> }
> >> - /* EBX value of main leaf 0 depends on enabled xsave features */
> >> - if ( count == 0 && v->arch.xcr0 )
> >> - {
> >> - /* reset EBX to default value first */
> >> - *ebx = XSTATE_AREA_MIN_SIZE;
> >> - for ( sub_leaf = 2; sub_leaf < 63; sub_leaf++ )
> >> - {
> >> - if ( !(v->arch.xcr0 & (1ULL << sub_leaf)) )
> >> - continue;
> >> - domain_cpuid(d, input, sub_leaf, &_eax, &_ebx, &_ecx,
> >> - &_edx);
> >> - if ( (_eax + _ebx) > *ebx )
> >> - *ebx = _eax + _ebx;
> >> - }
> >> - }
> >> -
> >> - if ( count == 1 )
> >> + switch ( count )
> >> {
> >> + case 1:
> >> *eax &= hvm_featureset[FEATURESET_Da1];
> >> -
> >> - if ( *eax & cpufeat_mask(X86_FEATURE_XSAVES) )
> >> + if ( !(*eax & cpufeat_mask(X86_FEATURE_XSAVES)) )
> >> {
> >> - uint64_t xfeatures = v->arch.xcr0 |
> >> v->arch.hvm_vcpu.msr_xss;
> >> -
> >> - *ebx = XSTATE_AREA_MIN_SIZE;
> >> - if ( xfeatures & ~XSTATE_FP_SSE )
> >> - for ( sub_leaf = 2; sub_leaf < 63; sub_leaf++ )
> >> - if ( xfeatures & (1ULL << sub_leaf) )
> >> - {
> >> - if ( test_bit(sub_leaf, &xstate_align) )
> >> - *ebx = ROUNDUP(*ebx, 64);
> >> - *ebx += xstate_sizes[sub_leaf];
> >> - }
> >> - }
> >> - else
> >> *ebx = *ecx = *edx = 0;
> >> + break;
> >> + }
> >> + /* fall through */
> >> + case 0:
> >> + /*
> >> + * Always read CPUID.0xD[ECX=0/1].EBX from hardware, rather
> >> than
> >> + * domain policy. It varies with enabled xstate, and the
> >> correct
> >> + * xcr0/xss are in context.
> >> + */
> >> + cpuid_count(input, count, &dummy, ebx, &dummy, &dummy);
> >> + break;
> >
> > It would be helpful for my PKU bugfix if you could avoid collapsing this
> > into a fallthough, as the fallthough would need to be undone.
> > Otherwise, Reviewed-by: Andrew Cooper <andrew.coop...@citrix.com>
>
> Converting this back is easy to do, but I'll nevertheless wait for
> Wei's opinion re 4.7 inclusion, as otherwise I'll eventually need to
> rebase on top of yours anyway.
>
I think this is fine for 4.7. And I will leave it to you two to
coordinate the rest.
Wei.
> Jan
>
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