x86/xsaves: Use xsaves/xrstors to save and restore xsave area

If xsaves is eanbled, use xsaves/xrstors instrucitons to save and restore
xstate. xsaves and xrstors support compacted format, init optimization,
modified optimization, and supervisor states.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1401387164-43416-9-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 64 insertions, 20 deletions

diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h
index 76c2459188c8..f9177a2a97e9 100644
--- a/arch/x86/include/asm/xsave.h
+++ b/arch/x86/include/asm/xsave.h
@@ -65,6 +65,70 @@ extern int init_fpu(struct task_struct *child);
                         _ASM_EXTABLE(1b, 3b)            \
                         : [err] "=r" (err)
 
+/*
+ * Save processor xstate to xsave area.
+ */
+static inline int xsave_state(struct xsave_struct *fx, u64 mask)
+{
+        u32 lmask = mask;
+        u32 hmask = mask >> 32;
+        int err = 0;
+
+        /*
+         * If xsaves is enabled, xsaves replaces xsaveopt because
+         * it supports compact format and supervisor states in addition to
+         * modified optimization in xsaveopt.
+         *
+         * Otherwise, if xsaveopt is enabled, xsaveopt replaces xsave
+         * because xsaveopt supports modified optimization which is not
+         * supported by xsave.
+         *
+         * If none of xsaves and xsaveopt is enabled, use xsave.
+         */
+        alternative_input_2(
+                "1:"XSAVE,
+                "1:"XSAVEOPT,
+                X86_FEATURE_XSAVEOPT,
+                "1:"XSAVES,
+                X86_FEATURE_XSAVES,
+                [fx] "D" (fx), "a" (lmask), "d" (hmask) :
+                "memory");
+        asm volatile("2:\n\t"
+                     xstate_fault
+                     : "0" (0)
+                     : "memory");
+
+        return err;
+}
+
+/*
+ * Restore processor xstate from xsave area.
+ */
+static inline int xrstor_state(struct xsave_struct *fx, u64 mask)
+{
+        int err = 0;
+        u32 lmask = mask;
+        u32 hmask = mask >> 32;
+
+        /*
+         * Use xrstors to restore context if it is enabled. xrstors supports
+         * compacted format of xsave area which is not supported by xrstor.
+         */
+        alternative_input(
+                "1: " XRSTOR,
+                "1: " XRSTORS,
+                X86_FEATURE_XSAVES,
+                "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+                : "memory");
+
+        asm volatile("2:\n"
+                     xstate_fault
+                     : "0" (0)
+                     : "memory");
+
+        return err;
+}
+
 static inline int fpu_xrstor_checking(struct xsave_struct *fx)
 {
         int err;
@@ -130,26 +194,6 @@ static inline int xrestore_user(struct xsave_struct __user *buf, u64 mask)
         return err;
 }
 
-static inline void xrstor_state(struct xsave_struct *fx, u64 mask)
-{
-        u32 lmask = mask;
-        u32 hmask = mask >> 32;
-
-        asm volatile(".byte " REX_PREFIX "0x0f,0xae,0x2f\n\t"
-                     : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
-                     :   "memory");
-}
-
-static inline void xsave_state(struct xsave_struct *fx, u64 mask)
-{
-        u32 lmask = mask;
-        u32 hmask = mask >> 32;
-
-        asm volatile(".byte " REX_PREFIX "0x0f,0xae,0x27\n\t"
-                     : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
-                     :   "memory");
-}
-
 static inline void fpu_xsave(struct fpu *fpu)
 {
         /* This, however, we can work around by forcing the compiler to select