x86: add macro for privileged 64-bit operation

i386 has a macro GET_CR0_INTO_EAX, used in early trap handling code.
x86_64 has similar needs, only it needs to put cr2 into rcx. We provide
a macro for such task, in the same way

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/asm-x86/paravirt.h

@@ -1227,6 +1227,12 @@ static inline unsigned long __raw_local_irq_save(void)
 	push %ecx; push %edx;			\
 	call *pv_cpu_ops+PV_CPU_read_cr0;	\
 	pop %edx; pop %ecx
+#else
+#define GET_CR2_INTO_RCX			\
+	call *pv_mmu_ops+PV_MMU_read_cr2;	\
+	movq %rax, %rcx;			\
+	xorq %rax, %rax;
+
 #endif
 
 #endif /* __ASSEMBLY__ */