xen/arm: support VCPUOP_register_vcpu_info.

We don't want to support the full vcpu_op hypercall interface, just
VCPUOP_register_vcpu_info: introduce an internal ARM-only
do_arm_vcpu_op function to filter out the vcpu_op hypercalls that
we don't want to support.
Call do_arm_vcpu_op instead of do_vcpu_op from traps.c.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Keir Fraser <keir@xen.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

xen/arch/arm/domain.c

@@ -10,6 +10,7 @@
  * GNU General Public License for more details.
  */
 #include <xen/config.h>
+#include <xen/hypercall.h>
 #include <xen/init.h>
 #include <xen/lib.h>
 #include <xen/sched.h>
@@ -629,6 +630,18 @@ void arch_dump_domain_info(struct domain *d)
     }
 }
 
+
+long do_arm_vcpu_op(int cmd, int vcpuid, XEN_GUEST_HANDLE_PARAM(void) arg)
+{
+    switch ( cmd )
+    {
+        case VCPUOP_register_vcpu_info:
+            return do_vcpu_op(cmd, vcpuid, arg);
+        default:
+            return -EINVAL;
+    }
+}
+
 long arch_do_vcpu_op(int cmd, struct vcpu *v, XEN_GUEST_HANDLE_PARAM(void) arg)
 {
     return -ENOSYS;

xen/arch/arm/traps.c

@@ -653,6 +653,11 @@ typedef struct {
         .nr_args = _nr_args,                                         \
     }
 
+#define HYPERCALL_ARM(_name, _nr_args)                        \
+    [ __HYPERVISOR_ ## _name ] =  {                                  \
+        .fn = (arm_hypercall_fn_t) &do_arm_ ## _name,                \
+        .nr_args = _nr_args,                                         \
+    }
 static arm_hypercall_t arm_hypercall_table[] = {
     HYPERCALL(memory_op, 2),
     HYPERCALL(domctl, 1),
@@ -665,6 +670,7 @@ static arm_hypercall_t arm_hypercall_table[] = {
     HYPERCALL(sysctl, 2),
     HYPERCALL(hvm_op, 2),
     HYPERCALL(grant_table_op, 3),
+    HYPERCALL_ARM(vcpu_op, 3),
 };
 
 #define __PSCI_cpu_suspend 0

xen/include/asm-arm/hypercall.h

@@ -4,6 +4,8 @@
 #include <public/domctl.h> /* for arch_do_domctl */
 int do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg);
 
+long do_arm_vcpu_op(int cmd, int vcpuid, XEN_GUEST_HANDLE_PARAM(void) arg);
+
 #endif /* __ASM_ARM_HYPERCALL_H__ */
 /*
  * Local variables: