x86/xen: use capabilities instead of fake cpuid values for x2apic

When running as pv domain xen_cpuid() is being used instead of
native_cpuid(). In xen_cpuid() the x2apic feature is indicated as not
being present by special casing the related cpuid leaf.

Instead of delivering fake cpuid values clear the cpu capability bit
for x2apic instead.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

arch/x86/xen/enlighten_pv.c

@@ -286,8 +286,6 @@ static void __init xen_init_cpuid_mask(void)
 	unsigned int ax, bx, cx, dx;
 	unsigned int xsave_mask;
 
-	cpuid_leaf1_ecx_mask &= ~(1 << (X86_FEATURE_X2APIC % 32));
-
 	ax = 1;
 	cx = 0;
 	cpuid(1, &ax, &bx, &cx, &dx);
@@ -309,6 +307,7 @@ static void __init xen_init_capabilities(void)
 	setup_clear_cpu_cap(X86_FEATURE_APERFMPERF);
 	setup_clear_cpu_cap(X86_FEATURE_MTRR);
 	setup_clear_cpu_cap(X86_FEATURE_ACC);
+	setup_clear_cpu_cap(X86_FEATURE_X2APIC);
 
 	if (!xen_initial_domain())
 		setup_clear_cpu_cap(X86_FEATURE_ACPI);