On Fri, Jun 10, 2016 at 07:17:43PM +0100, Andrew Cooper wrote:
> PKU lives in CPUID.7[0].ECX, not EBX. This causes hardware with BMI1 to
> accidentally advertise PKU in CPUID.0xD[0].EAX. Any OS which proceeds to
> blindly write this into %xcr0 takes a #GP fault. (Experimentally, Windows
> Vista 32bit falls into this category.)
>
> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
> ---
> CC: Jan Beulich <jbeul...@suse.com>
> CC: Wei Liu <wei.l...@citrix.com>
>
Reviewed-by: Wei Liu <wei.l...@citrix.com>
and
Release-acked-by: Wei Liu <wei.l...@citrix.com>
> This is all going to be far less error prone when I have guest_has_$FEATURE(v)
> helpers which read the bits out of a flat array...
> ---
> xen/arch/x86/hvm/hvm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index e664b34..78db903 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -3466,7 +3466,7 @@ void hvm_cpuid(unsigned int input, unsigned int *eax,
> unsigned int *ebx,
> xstate_sizes[_XSTATE_BNDCSR]);
> }
>
> - if ( _ebx & cpufeat_mask(X86_FEATURE_PKU) )
> + if ( _ecx & cpufeat_mask(X86_FEATURE_PKU) )
> {
> xfeature_mask |= XSTATE_PKRU;
> xstate_size = max(xstate_size,
> --
> 2.1.4
>
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