[PATCH] x86: don't expose SYSENTER on unknown CPUs

[PATCH] x86: don't expose SYSENTER on unknown CPUs

[Jan Beulich]

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So far we only ever set up the respective MSRs on Intel CPUs, yet we
hide the feature only on a 32-bit hypervisor. That prevents booting of
PV guests on top of a 64-bit hypervisor making use of the instruction
on unknown CPUs (VIA in this case).

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -55,6 +55,7 @@ static void default_init(struct cpuinfo_
 	/* Not much we can do here... */
 	/* Check if at least it has cpuid */
 	BUG_ON(c->cpuid_level == -1);
+	__clear_bit(X86_FEATURE_SEP, c->x86_capability);
 }
 
 static struct cpu_dev default_cpu = {




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x86: don't expose SYSENTER on unknown CPUs

So far we only ever set up the respective MSRs on Intel CPUs, yet we
hide the feature only on a 32-bit hypervisor. That prevents booting of
PV guests on top of a 64-bit hypervisor making use of the instruction
on unknown CPUs (VIA in this case).

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -55,6 +55,7 @@ static void default_init(struct cpuinfo_
 	/* Not much we can do here... */
 	/* Check if at least it has cpuid */
 	BUG_ON(c->cpuid_level == -1);
+	__clear_bit(X86_FEATURE_SEP, c->x86_capability);
 }
 
 static struct cpu_dev default_cpu = {

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Re: [PATCH] x86: don't expose SYSENTER on unknown CPUs

[Keir Fraser]

On 17/08/2012 17:25, "Jan Beulich" <JBeulich@suse.com> wrote:

> So far we only ever set up the respective MSRs on Intel CPUs, yet we
> hide the feature only on a 32-bit hypervisor. That prevents booting of
> PV guests on top of a 64-bit hypervisor making use of the instruction
> on unknown CPUs (VIA in this case).
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Keir Fraser <keir@xen.org>

> --- a/xen/arch/x86/cpu/common.c
> +++ b/xen/arch/x86/cpu/common.c
> @@ -55,6 +55,7 @@ static void default_init(struct cpuinfo_
> /* Not much we can do here... */
> /* Check if at least it has cpuid */
> BUG_ON(c->cpuid_level == -1);
> + __clear_bit(X86_FEATURE_SEP, c->x86_capability);
>  }
>  
>  static struct cpu_dev default_cpu = {
> 
> 
> 
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