x86, xsave: context switch support using xsave/xrstor

Uses xsave/xrstor (instead of traditional fxsave/fxrstor) in context switch
when available.

Introduces TS_XSAVE flag, which determine the need to use xsave/xrstor
instructions during context switch instead of the legacy fxsave/fxrstor
instructions. Thread-synchronous status word is already in L1 cache during
this code patch and thus minimizes the performance penality compared to
(cpu_has_xsave) checks.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/asm-x86/processor.h b/include/asm-x86/processor.h
index d7c0221c0278..77b7af6b573b 100644
--- a/include/asm-x86/processor.h
+++ b/include/asm-x86/processor.h
@@ -362,6 +362,7 @@ union thread_xstate {
         struct i387_fsave_struct        fsave;
         struct i387_fxsave_struct       fxsave;
         struct i387_soft_struct         soft;
+        struct xsave_struct             xsave;
 };
 
 #ifdef CONFIG_X86_64