vfio/container: ram discard disable helper

Define a helper to set ram discard disable, generate error messages,
and cleanup on failure.  The second vfio_ram_block_discard_disable
call site now performs VFIO_GROUP_UNSET_CONTAINER immediately on failure,
instead of relying on the close of the container fd to do so in the kernel,
but this is equivalent.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Cedric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/1746195760-101443-2-git-send-email-steven.sistare@oracle.com
[ clg: vfio_attach_discard_disable() -> vfio_container_attach_discard_disable() ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>

1 files changed, 27 insertions, 21 deletions

diff --git a/hw/vfio/container.c b/hw/vfio/container.c
index 77ff56b..2ea137f 100644
--- a/hw/vfio/container.c
+++ b/hw/vfio/container.c
@@ -511,16 +511,10 @@ static bool vfio_legacy_setup(VFIOContainerBase *bcontainer, Error **errp)
     return true;
 }
 
-static bool vfio_container_connect(VFIOGroup *group, AddressSpace *as,
-                                   Error **errp)
+static bool vfio_container_attach_discard_disable(VFIOContainer *container,
+                                            VFIOGroup *group, Error **errp)
 {
-    VFIOContainer *container;
-    VFIOContainerBase *bcontainer;
-    int ret, fd;
-    VFIOAddressSpace *space;
-    VFIOIOMMUClass *vioc;
-
-    space = vfio_address_space_get(as);
+    int ret;
 
     /*
      * VFIO is currently incompatible with discarding of RAM insofar as the
@@ -553,18 +547,32 @@ static bool vfio_container_connect(VFIOGroup *group, AddressSpace *as,
      * details once we know which type of IOMMU we are using.
      */
 
+    ret = vfio_ram_block_discard_disable(container, true);
+    if (ret) {
+        error_setg_errno(errp, -ret, "Cannot set discarding of RAM broken");
+        if (ioctl(group->fd, VFIO_GROUP_UNSET_CONTAINER, &container->fd)) {
+            error_report("vfio: error disconnecting group %d from"
+                         " container", group->groupid);
+        }
+    }
+    return !ret;
+}
+
+static bool vfio_container_connect(VFIOGroup *group, AddressSpace *as,
+                                   Error **errp)
+{
+    VFIOContainer *container;
+    VFIOContainerBase *bcontainer;
+    int ret, fd;
+    VFIOAddressSpace *space;
+    VFIOIOMMUClass *vioc;
+
+    space = vfio_address_space_get(as);
+
     QLIST_FOREACH(bcontainer, &space->containers, next) {
         container = container_of(bcontainer, VFIOContainer, bcontainer);
         if (!ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &container->fd)) {
-            ret = vfio_ram_block_discard_disable(container, true);
-            if (ret) {
-                error_setg_errno(errp, -ret,
-                                 "Cannot set discarding of RAM broken");
-                if (ioctl(group->fd, VFIO_GROUP_UNSET_CONTAINER,
-                          &container->fd)) {
-                    error_report("vfio: error disconnecting group %d from"
-                                 " container", group->groupid);
-                }
+            if (!vfio_container_attach_discard_disable(container, group, errp)) {
                 return false;
             }
             group->container = container;
@@ -596,9 +604,7 @@ static bool vfio_container_connect(VFIOGroup *group, AddressSpace *as,
         goto free_container_exit;
     }
 
-    ret = vfio_ram_block_discard_disable(container, true);
-    if (ret) {
-        error_setg_errno(errp, -ret, "Cannot set discarding of RAM broken");
+    if (!vfio_container_attach_discard_disable(container, group, errp)) {
         goto unregister_container_exit;
     }