From: Wei Liu <wei.liu2@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>, Jan Beulich <JBeulich@suse.com>,
Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH for-4.7] xen/hvm: Fix advertisment of available xstates following c/s c52319642
Date: Fri, 10 Jun 2016 19:29:05 +0100 [thread overview]
Message-ID: <20160610182904.GM28116@citrix.com> (raw)
In-Reply-To: <1465582663-15317-1-git-send-email-andrew.cooper3@citrix.com>
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.cooper3@citrix.com>
> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Wei Liu <wei.liu2@citrix.com>
>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
and
Release-acked-by: Wei Liu <wei.liu2@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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next prev parent reply other threads:[~2016-06-10 18:29 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-10 18:17 [PATCH for-4.7] xen/hvm: Fix advertisment of available xstates following c/s c52319642 Andrew Cooper
2016-06-10 18:29 ` Wei Liu [this message]
2016-06-13 9:48 ` Jan Beulich
2016-06-13 10:42 ` Wei Liu
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