[PATCH v3 2/3] hw/virtio: cleanup shared resources

[Albert Esteve <aesteve@redhat.com>]

Ensure that we cleanup all virtio shared
resources when the vhost devices is cleaned
up (after a hot unplug, or a crash).

To do so, we add a new function to the virtio_dmabuf
API called `virtio_dmabuf_vhost_cleanup`, which
loop through the table and removes all
resources owned by the vhost device parameter.

Also, add a test to verify that the new
function in the API behaves as expected.

Signed-off-by: Albert Esteve <aesteve@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 hw/display/virtio-dmabuf.c        | 22 +++++++++++++++++++++
 hw/virtio/vhost.c                 |  3 +++
 include/hw/virtio/virtio-dmabuf.h | 10 ++++++++++
 tests/unit/test-virtio-dmabuf.c   | 33 +++++++++++++++++++++++++++++++
 4 files changed, 68 insertions(+)

diff --git a/hw/display/virtio-dmabuf.c b/hw/display/virtio-dmabuf.c
index 3dba4577ca..6688809777 100644
--- a/hw/display/virtio-dmabuf.c
+++ b/hw/display/virtio-dmabuf.c
@@ -136,6 +136,28 @@ SharedObjectType virtio_object_type(const QemuUUID *uuid)
     return vso->type;
 }
 
+static bool virtio_dmabuf_resource_is_owned(gpointer key,
+                                            gpointer value,
+                                            gpointer dev)
+{
+    VirtioSharedObject *vso;
+
+    vso = (VirtioSharedObject *) value;
+    return vso->type == TYPE_VHOST_DEV && vso->value == dev;
+}
+
+int virtio_dmabuf_vhost_cleanup(struct vhost_dev *dev)
+{
+    int num_removed;
+
+    g_mutex_lock(&lock);
+    num_removed = g_hash_table_foreach_remove(
+        resource_uuids, (GHRFunc) virtio_dmabuf_resource_is_owned, dev);
+    g_mutex_unlock(&lock);
+
+    return num_removed;
+}
+
 void virtio_free_resources(void)
 {
     g_mutex_lock(&lock);
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 2c9ac79468..c5622eac14 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -16,6 +16,7 @@
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "hw/virtio/vhost.h"
+#include "hw/virtio/virtio-dmabuf.h"
 #include "qemu/atomic.h"
 #include "qemu/range.h"
 #include "qemu/error-report.h"
@@ -1599,6 +1600,8 @@ void vhost_dev_cleanup(struct vhost_dev *hdev)
     migrate_del_blocker(&hdev->migration_blocker);
     g_free(hdev->mem);
     g_free(hdev->mem_sections);
+    /* free virtio shared objects */
+    virtio_dmabuf_vhost_cleanup(hdev);
     if (hdev->vhost_ops) {
         hdev->vhost_ops->vhost_backend_cleanup(hdev);
     }
diff --git a/include/hw/virtio/virtio-dmabuf.h b/include/hw/virtio/virtio-dmabuf.h
index 627c3b6db7..73f70fb482 100644
--- a/include/hw/virtio/virtio-dmabuf.h
+++ b/include/hw/virtio/virtio-dmabuf.h
@@ -91,6 +91,16 @@ struct vhost_dev *virtio_lookup_vhost_device(const QemuUUID *uuid);
  */
 SharedObjectType virtio_object_type(const QemuUUID *uuid);
 
+/**
+ * virtio_dmabuf_vhost_cleanup() - Destroys all entries of the shared
+ * resources lookup table that are owned by the vhost backend
+ * @dev: the pointer to the vhost device that owns the entries. Data is owned
+ *       by the called of the function.
+ * 
+ * Return: the number of resource entries removed.
+ */
+int virtio_dmabuf_vhost_cleanup(struct vhost_dev *dev);
+
 /**
  * virtio_free_resources() - Destroys all keys and values of the shared
  * resources lookup table, and frees them
diff --git a/tests/unit/test-virtio-dmabuf.c b/tests/unit/test-virtio-dmabuf.c
index a45ec52f42..1c8123c2d2 100644
--- a/tests/unit/test-virtio-dmabuf.c
+++ b/tests/unit/test-virtio-dmabuf.c
@@ -103,6 +103,38 @@ static void test_add_invalid_resource(void)
     }
 }
 
+static void test_cleanup_res(void)
+{
+    QemuUUID uuids[20], uuid_alt;
+    struct vhost_dev *dev = g_new0(struct vhost_dev, 1);
+    struct vhost_dev *dev_alt = g_new0(struct vhost_dev, 1);
+    int i, num_removed;
+
+    for (i = 0; i < ARRAY_SIZE(uuids); ++i) {
+        qemu_uuid_generate(&uuids[i]);
+        virtio_add_vhost_device(&uuids[i], dev);
+        /* vhost device is found */
+        g_assert(virtio_lookup_vhost_device(&uuids[i]) != NULL);
+    }
+    qemu_uuid_generate(&uuid_alt);
+    virtio_add_vhost_device(&uuid_alt, dev_alt);
+    /* vhost device is found */
+    g_assert(virtio_lookup_vhost_device(&uuid_alt) != NULL);
+    /* cleanup all dev resources */
+    num_removed = virtio_dmabuf_vhost_cleanup(dev);
+    g_assert_cmpint(num_removed, ==, ARRAY_SIZE(uuids));
+    for (i = 0; i < ARRAY_SIZE(uuids); ++i) {
+        /* None of the dev resources is found after free'd */
+        g_assert_cmpint(virtio_lookup_dmabuf(&uuids[i]), ==, -1);
+    }
+    /* uuid_alt is still in the hash table */
+    g_assert(virtio_lookup_vhost_device(&uuid_alt) != NULL);
+
+    virtio_free_resources();
+    g_free(dev);
+    g_free(dev_alt);
+}
+
 static void test_free_resources(void)
 {
     QemuUUID uuids[20];
@@ -131,6 +163,7 @@ int main(int argc, char **argv)
                     test_remove_invalid_resource);
     g_test_add_func("/virtio-dmabuf/add_invalid_res",
                     test_add_invalid_resource);
+    g_test_add_func("/virtio-dmabuf/cleanup_dev", test_cleanup_res);
     g_test_add_func("/virtio-dmabuf/free_res", test_free_resources);
 
     return g_test_run();
-- 
2.43.0