[PATCH RFC XEN v1 03/14] xen: arm: switch arch_do_domctl to a common exit path

[Ian Campbell <ian.campbell@citrix.com>]

... with copyback functionality. A future domctl is going to want
this, rather than end up with different ops having different return
behaviour, simply switch everything over to a single exit path scheme.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
---
 xen/arch/arm/domctl.c | 76 ++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 51 insertions(+), 25 deletions(-)

diff --git a/xen/arch/arm/domctl.c b/xen/arch/arm/domctl.c
index 30453d8..d42b2bf 100644
--- a/xen/arch/arm/domctl.c
+++ b/xen/arch/arm/domctl.c
@@ -12,11 +12,15 @@
 #include <xen/hypercall.h>
 #include <xen/iocap.h>
 #include <xsm/xsm.h>
+#include <xen/guest_access.h>
 #include <public/domctl.h>
 
 long arch_do_domctl(struct xen_domctl *domctl, struct domain *d,
                     XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
 {
+    long rc;
+    bool_t copyback = 0;
+
     switch ( domctl->cmd )
     {
     case XEN_DOMCTL_cacheflush:
@@ -25,30 +29,36 @@ long arch_do_domctl(struct xen_domctl *domctl, struct domain *d,
         unsigned long e = s + domctl->u.cacheflush.nr_pfns;
 
         if ( domctl->u.cacheflush.nr_pfns > (1U<<MAX_ORDER) )
-            return -EINVAL;
-
-        if ( e < s )
-            return -EINVAL;
+            rc = -EINVAL;
+        else if ( e < s )
+            rc = -EINVAL;
+        else
+            rc = p2m_cache_flush(d, s, e);
 
-        return p2m_cache_flush(d, s, e);
+        break;
     }
     case XEN_DOMCTL_bind_pt_irq:
     {
-        int rc;
         xen_domctl_bind_pt_irq_t *bind = &domctl->u.bind_pt_irq;
         uint32_t irq = bind->u.spi.spi;
         uint32_t virq = bind->machine_irq;
 
         /* We only support PT_IRQ_TYPE_SPI */
         if ( bind->irq_type != PT_IRQ_TYPE_SPI )
-            return -EOPNOTSUPP;
+        {
+            rc = -EOPNOTSUPP;
+            break;
+        }
 
         /*
          * XXX: For now map the interrupt 1:1. Other support will require to
          * modify domain_pirq_to_irq macro.
          */
         if ( irq != virq )
-            return -EINVAL;
+        {
+            rc = -EINVAL;
+            break;
+        }
 
         /*
          * ARM doesn't require separating IRQ assignation into 2
@@ -60,66 +70,82 @@ long arch_do_domctl(struct xen_domctl *domctl, struct domain *d,
          */
         rc = xsm_map_domain_irq(XSM_HOOK, d, irq, NULL);
         if ( rc )
-            return rc;
+            break;
 
         rc = xsm_bind_pt_irq(XSM_HOOK, d, bind);
         if ( rc )
-            return rc;
+            break;
 
         if ( !irq_access_permitted(current->domain, irq) )
-            return -EPERM;
+        {
+            rc = -EPERM;
+            break;
+        }
 
         if ( !vgic_reserve_virq(d, virq) )
-            return -EBUSY;
+        {
+            rc = -EBUSY;
+            break;
+        }
 
         rc = route_irq_to_guest(d, virq, irq, "routed IRQ");
         if ( rc )
             vgic_free_virq(d, virq);
 
-        return rc;
+        break;
     }
     case XEN_DOMCTL_unbind_pt_irq:
     {
-        int rc;
         xen_domctl_bind_pt_irq_t *bind = &domctl->u.bind_pt_irq;
         uint32_t irq = bind->u.spi.spi;
         uint32_t virq = bind->machine_irq;
 
         /* We only support PT_IRQ_TYPE_SPI */
         if ( bind->irq_type != PT_IRQ_TYPE_SPI )
-            return -EOPNOTSUPP;
+        {
+            rc = -EOPNOTSUPP;
+            break;
+        }
 
         /* For now map the interrupt 1:1 */
         if ( irq != virq )
-            return -EINVAL;
+        {
+            rc = -EINVAL;
+            break;
+        }
 
         rc = xsm_unbind_pt_irq(XSM_HOOK, d, bind);
         if ( rc )
-            return rc;
+            break;
 
         if ( !irq_access_permitted(current->domain, irq) )
-            return -EPERM;
+        {
+            rc = -EPERM;
+            break;
+        }
 
         rc = release_guest_irq(d, virq);
         if ( rc )
-            return rc;
+            break;
 
         vgic_free_virq(d, virq);
 
-        return 0;
+        rc = 0;
+        break;
     }
     default:
-    {
-        int rc;
-
         rc = subarch_do_domctl(domctl, d, u_domctl);
 
         if ( rc == -ENOSYS )
             rc = iommu_do_domctl(domctl, d, u_domctl);
 
-        return rc;
-    }
+        break;
     }
+
+    if ( copyback && __copy_to_guest(u_domctl, domctl, 1) )
+        rc = -EFAULT;
+
+    return rc;
 }
 
 void arch_get_info_guest(struct vcpu *v, vcpu_guest_context_u c)
-- 
2.6.1