xen/arch/*: add struct domain parameter to arch_do_domctl

Since the arch-independent do_domctl function now RCU locks the domain
specified by op->domain, pass the struct domain to the arch-specific
domctl function and remove the duplicate per-subfunction locking.

This also removes two get_domain/put_domain call pairs (in
XEN_DOMCTL_assign_device and XEN_DOMCTL_deassign_device), replacing
them with RCU locking.
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Tim Deegan <tim@xen.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Committed-by: Keir Fraser <keir@xen.org>

xen/arch/arm/domctl.c

@@ -10,7 +10,7 @@
 #include <xen/errno.h>
 #include <public/domctl.h>
 
-long arch_do_domctl(struct xen_domctl *domctl,
+long arch_do_domctl(struct xen_domctl *domctl, struct domain *d,
                     XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
 {
     return -ENOSYS;

xen/common/domctl.c

@@ -882,7 +882,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
     break;
 
     default:
-        ret = arch_do_domctl(op, u_domctl);
+        ret = arch_do_domctl(op, d, u_domctl);
         break;
     }
 

xen/drivers/passthrough/iommu.c

@@ -542,10 +542,9 @@ void iommu_crash_shutdown(void)
 }
 
 int iommu_do_domctl(
-    struct xen_domctl *domctl,
+    struct xen_domctl *domctl, struct domain *d,
     XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
 {
-    struct domain *d;
     u16 seg;
     u8 bus, devfn;
     int ret = 0;
@@ -564,10 +563,6 @@ int iommu_do_domctl(
         if ( ret )
             break;
 
-        ret = -EINVAL;
-        if ( (d = rcu_lock_domain_by_id(domctl->domain)) == NULL )
-            break;
-
         seg = domctl->u.get_device_group.machine_sbdf >> 16;
         bus = (domctl->u.get_device_group.machine_sbdf >> 8) & 0xff;
         devfn = domctl->u.get_device_group.machine_sbdf & 0xff;
@@ -588,7 +583,6 @@ int iommu_do_domctl(
         }
         if ( __copy_field_to_guest(u_domctl, domctl, u.get_device_group) )
             ret = -EFAULT;
-        rcu_unlock_domain(d);
     }
     break;
 
@@ -611,20 +605,15 @@ int iommu_do_domctl(
         break;
 
     case XEN_DOMCTL_assign_device:
-        if ( unlikely((d = get_domain_by_id(domctl->domain)) == NULL) ||
-             unlikely(d->is_dying) )
+        if ( unlikely(d->is_dying) )
         {
-            printk(XENLOG_G_ERR
-                   "XEN_DOMCTL_assign_device: get_domain_by_id() failed\n");
             ret = -EINVAL;
-            if ( d )
-                goto assign_device_out;
             break;
         }
 
         ret = xsm_assign_device(d, domctl->u.assign_device.machine_sbdf);
         if ( ret )
-            goto assign_device_out;
+            break;
 
         seg = domctl->u.get_device_group.machine_sbdf >> 16;
         bus = (domctl->u.assign_device.machine_sbdf >> 8) & 0xff;
@@ -638,22 +627,12 @@ int iommu_do_domctl(
                    seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
                    d->domain_id, ret);
 
-    assign_device_out:
-        put_domain(d);
         break;
 
     case XEN_DOMCTL_deassign_device:
-        if ( unlikely((d = get_domain_by_id(domctl->domain)) == NULL) )
-        {
-            printk(XENLOG_G_ERR
-                   "XEN_DOMCTL_deassign_device: get_domain_by_id() failed\n");
-            ret = -EINVAL;
-            break;
-        }
-
         ret = xsm_deassign_device(d, domctl->u.assign_device.machine_sbdf);
         if ( ret )
-            goto deassign_device_out;
+            break;
 
         seg = domctl->u.get_device_group.machine_sbdf >> 16;
         bus = (domctl->u.assign_device.machine_sbdf >> 8) & 0xff;
@@ -668,8 +647,6 @@ int iommu_do_domctl(
                    seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
                    d->domain_id, ret);
 
-    deassign_device_out:
-        put_domain(d);
         break;
 
     default:

xen/include/xen/hypercall.h

@@ -37,7 +37,7 @@ do_domctl(
 
 extern long
 arch_do_domctl(
-    struct xen_domctl *domctl,
+    struct xen_domctl *domctl, struct domain *d,
     XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl);
 
 extern long

xen/include/xen/iommu.h

@@ -132,7 +132,8 @@ void iommu_crash_shutdown(void);
 void iommu_set_dom0_mapping(struct domain *d);
 void iommu_share_p2m_table(struct domain *d);
 
-int iommu_do_domctl(struct xen_domctl *, XEN_GUEST_HANDLE_PARAM(xen_domctl_t));
+int iommu_do_domctl(struct xen_domctl *, struct domain *d,
+                    XEN_GUEST_HANDLE_PARAM(xen_domctl_t));
 
 void iommu_iotlb_flush(struct domain *d, unsigned long gfn, unsigned int page_count);
 void iommu_iotlb_flush_all(struct domain *d);