xen: don't bother trying to set cr4

Xen ignores all updates to cr4, and some versions will kill the domain if
you try to change its value.  Just ignore all changes.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/i386/xen/enlighten.c b/arch/i386/xen/enlighten.c
index f0c37511d8da82d6e30650a6d7f0cc6cbd6dd368..f01bfcd4bdee4c63059ff2a2fd9f8ec4b1b0d1e1 100644 (file)
--- a/arch/i386/xen/enlighten.c
+++ b/arch/i386/xen/enlighten.c
@@ -623,8 +623,8 @@ static unsigned long xen_read_cr2_direct(void)
 
 static void xen_write_cr4(unsigned long cr4)
 {
-       /* never allow TSC to be disabled */
-       native_write_cr4(cr4 & ~X86_CR4_TSD);
+       /* Just ignore cr4 changes; Xen doesn't allow us to do
+          anything anyway. */
 }
 
 static unsigned long xen_read_cr3(void)