x86, xsave: Disable xsave in i387 emulation mode

xsave is broken for (!HAVE_HWFP). This is the case if config
MATH_EMULATION is enabled, 'no387' kernel parameter is set and xsave
exists. xsave will not work because x86/math-emu and xsave share the
same memory. As this case can be treated as corner case we simply
disable xsave then.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
LKML-Reference: <1279731838-1522-7-git-send-email-robert.richter@amd.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

arch/x86/kernel/i387.c

@@ -67,6 +67,12 @@ static void __cpuinit init_thread_xstate(void)
 	 */
 
 	if (!HAVE_HWFP) {
+		/*
+		 * Disable xsave as we do not support it if i387
+		 * emulation is enabled.
+		 */
+		setup_clear_cpu_cap(X86_FEATURE_XSAVE);
+		setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
 		xstate_size = sizeof(struct i387_soft_struct);
 		return;
 	}