x86/paravirt, 64-bit: don't restore user rsp within sysret

There's no need to combine restoring the user rsp within the sysret
pvop, so split it out.  This makes the pvop's semantics closer to the
machine instruction.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citirx.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-x86/irqflags.h b/include/asm-x86/irqflags.h
index 99ee525..544836c 100644
--- a/include/asm-x86/irqflags.h
+++ b/include/asm-x86/irqflags.h
@@ -112,8 +112,7 @@
 
 #ifdef CONFIG_X86_64
 #define INTERRUPT_RETURN	iretq
-#define USERSP_SYSRET					\
-			movq	%gs:pda_oldrsp, %rsp;	\
+#define USERGS_SYSRET					\
 			swapgs;				\
 			sysretq;
 #else