xen: mask out SEP from CPUID

[Chris Wright]

-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>

upstream commit: d40e705903397445c6861a0a56c23e5b2e8f9b9a

Fix 32-on-64 pvops kernel:

we don't want userspace using syscall/sysenter, even if the hypervisor
supports it, so mask it out from CPUID.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
 arch/x86/xen/enlighten.c |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -153,6 +153,7 @@ static void xen_cpuid(unsigned int *eax,
 	if (*eax == 1)
 		maskedx = ~((1 << X86_FEATURE_APIC) |  /* disable APIC */
 			    (1 << X86_FEATURE_ACPI) |  /* disable ACPI */
+			    (1 << X86_FEATURE_SEP)  |  /* disable SEP */
 			    (1 << X86_FEATURE_ACC));   /* thermal monitoring */
 
 	asm(XEN_EMULATE_PREFIX "cpuid"

-- 
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