[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 1/2] x86: flush high xstate CPUID sub-leaves to zero
On 01/06/16 16:05, Jan Beulich wrote: > In line with other recent changes, these should be fully white listed, > requiring us to zero them until the obtain a meaning we support. > > Without XSAVE support, all xstate sub-leaves should be zero. > > Also move away from checking host XSAVE support - we really ought to > consider the guest flag for that purpose. > > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, with one suggestion > > --- a/xen/arch/x86/hvm/hvm.c > +++ b/xen/arch/x86/hvm/hvm.c > @@ -3433,7 +3433,13 @@ void hvm_cpuid(unsigned int input, unsig > *edx = v->vcpu_id * 2; > break; > > - case 0xd: > + case XSTATE_CPUID: > + hvm_cpuid(1, NULL, NULL, &_ecx, NULL); > + if ( !(_ecx & cpufeat_mask(X86_FEATURE_XSAVE)) || count >= 63 ) > + { > + *eax = *ebx = *ecx = *edx = 0; > + break; > + } > /* EBX value of main leaf 0 depends on enabled xsave features */ > if ( count == 0 && v->arch.xcr0 ) > { > --- a/xen/arch/x86/traps.c > +++ b/xen/arch/x86/traps.c > @@ -928,6 +928,8 @@ void pv_cpuid(struct cpu_user_regs *regs > > switch ( leaf ) > { > + uint32_t tmp; > + > case 0x00000001: > c &= pv_featureset[FEATURESET_1c]; > d &= pv_featureset[FEATURESET_1d]; > @@ -1085,14 +1087,19 @@ void pv_cpuid(struct cpu_user_regs *regs > break; > > case XSTATE_CPUID: > - if ( !cpu_has_xsave ) > + if ( !((!is_control_domain(currd) && !is_hardware_domain(currd) I would recommend extra brackets on this line, to avoid the possible mis-interpretation of !is_control_domain(currd) && (!is_hardware_domain(currd) ? ... > + ? ({ > + uint32_t ecx; > + > + domain_cpuid(currd, 1, 0, &tmp, &tmp, &ecx, &tmp); > + ecx & pv_featureset[FEATURESET_1c]; > + }) > + : cpuid_ecx(1)) & cpufeat_mask(X86_FEATURE_XSAVE)) || > + subleaf >= 63 ) This is rather nasty code. I am glad that my longterm plans involve removing it all. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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