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: Robert Richter <robert.richter@amd.com>
LKML-Reference: <1279731838-1522-7-git-send-email-robert.richter@amd.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 1f11f5ce668f..2605c50b11d3 100644
--- a/arch/x86/kernel/i387.c
+++ b/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;
         }