also move compat mode VCPUOP_register_vcpu_info into common code

Otherwise, with arch_compat_vcpu_op() calling arch_do_vcpu_op() to
handle it, it results in -ENOSYS after 6ff9e4f7 ("xen: move
VCPUOP_register_vcpu_info to common code") for 32-bit x86 domains.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/x86_64/domain.c
+++ b/xen/arch/x86/x86_64/domain.c
@@ -9,14 +9,6 @@
 #include <xen/hypercall.h>
 #include <compat/vcpu.h>
 
-#define xen_vcpu_info vcpu_info
-CHECK_SIZE_(struct, vcpu_info);
-#undef xen_vcpu_info
-
-#define xen_vcpu_register_vcpu_info vcpu_register_vcpu_info
-CHECK_vcpu_register_vcpu_info;
-#undef xen_vcpu_register_vcpu_info
-
 #define xen_vcpu_get_physid vcpu_get_physid
 CHECK_vcpu_get_physid;
 #undef xen_vcpu_get_physid
@@ -63,7 +55,6 @@ arch_compat_vcpu_op(
         break;
     }
 
-    case VCPUOP_register_vcpu_info:
     case VCPUOP_get_physid:
         rc = arch_do_vcpu_op(cmd, v, arg);
         break;
--- a/xen/common/compat/domain.c
+++ b/xen/common/compat/domain.c
@@ -15,6 +15,14 @@
 CHECK_vcpu_set_periodic_timer;
 #undef xen_vcpu_set_periodic_timer
 
+#define xen_vcpu_info vcpu_info
+CHECK_SIZE_(struct, vcpu_info);
+#undef xen_vcpu_info
+
+#define xen_vcpu_register_vcpu_info vcpu_register_vcpu_info
+CHECK_vcpu_register_vcpu_info;
+#undef xen_vcpu_register_vcpu_info
+
 int compat_vcpu_op(int cmd, int vcpuid, XEN_GUEST_HANDLE_PARAM(void) arg)
 {
     struct domain *d = current->domain;
@@ -64,6 +72,7 @@ int compat_vcpu_op(int cmd, int vcpuid, 
     case VCPUOP_set_periodic_timer:
     case VCPUOP_stop_periodic_timer:
     case VCPUOP_stop_singleshot_timer:
+    case VCPUOP_register_vcpu_info:
     case VCPUOP_send_nmi:
         rc = do_vcpu_op(cmd, vcpuid, arg);
         break;