KVM: add hypercall nr to kvm_run

Add the hypercall number to kvm_run and initialize it.  This changes the ABI,
but as this particular ABI was unusable before this no users are affected.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 69d9ab4..2094746 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1378,6 +1378,7 @@
 	}
 	switch (nr) {
 	default:
+		run->hypercall.nr = nr;
 		run->hypercall.args[0] = a0;
 		run->hypercall.args[1] = a1;
 		run->hypercall.args[2] = a2;