x86, xsave: Use xsaveopt in context-switch path when supported
xsaveopt is a more optimized form of xsave specifically designed
for the context switch usage. xsaveopt doesn't save the state that's not
modified from the prior xrstor. And if a specific feature state gets
modified to the init state, then xsaveopt just updates the header bit
in the xsave memory layout without updating the corresponding memory
layout.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20100719230205.604014179@sbs-t61.sc.intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index bb370fd..59bd93a 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -60,7 +60,7 @@
static __always_inline __pure bool use_xsaveopt(void)
{
- return 0;
+ return static_cpu_has(X86_FEATURE_XSAVEOPT);
}
static __always_inline __pure bool use_xsave(void)