x86, xen: Suppress WP test on Xen

Xen always runs on CPUs which properly support WP enforcement in
privileged mode, so there's no need to test for it.

This also works around a crash reported by Arnd Hannemann, though I
think its just a band-aid for that case.

Reported-by: Arnd Hannemann <hannemann@nets.rwth-aachen.de>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index e90540a..0b755cd 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1059,6 +1059,7 @@
 	/* set up basic CPUID stuff */
 	cpu_detect(&new_cpu_data);
 	new_cpu_data.hard_math = 1;
+	new_cpu_data.wp_works_ok = 1;
 	new_cpu_data.x86_capability[0] = cpuid_edx(1);
 #endif