x86/xsaves: Clear reserved bits in xsave header

The reserved bits (128~511) in the xsave header must be zero according to
X86 SDM. Clear the bits in this patch.
Signed-off-by: NFenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1401387164-43416-12-git-send-email-fenghua.yu@intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

arch/x86/kernel/i387.c

@@ -375,7 +375,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
 	/*
 	 * These bits must be zero.
 	 */
-	xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
+	memset(xsave_hdr->reserved, 0, 48);
 
 	return ret;
 }