vhost: register and change IOMMU flag depending on Device-TLB state

The guest can disable or never enable Device-TLB. In these cases, it can't be used even if enabled in QEMU. So, check Device-TLB state before registering IOMMU notifier and select unmap flag depending on that. Also, implement a way to change IOMMU notifier flag if Device-TLB state is changed. Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2001312 Signed-off-by: Viktor Prutyanov <viktor@daynix.com> Acked-by: Jason Wang <jasowang@redhat.com> Message-Id: <20230626091258.24453-2-viktor@daynix.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
qemu · Jul 10, 2023 · ee071f6 · ee071f6
1 parent 2b5de4d
commit ee071f6
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Showing 3 changed files with 31 additions and 12 deletions.
diff --git a/hw/virtio/vhost-stub.c b/hw/virtio/vhost-stub.c
@@ -15,3 +15,7 @@ bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error **errp)
 void vhost_user_cleanup(VhostUserState *user)
 {
 }
+
+void vhost_toggle_device_iotlb(VirtIODevice *vdev)
+{
+}
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
@@ -780,7 +780,6 @@ static void vhost_iommu_region_add(MemoryListener *listener,
     Int128 end;
     int iommu_idx;
     IOMMUMemoryRegion *iommu_mr;
-    int ret;
 
     if (!memory_region_is_iommu(section->mr)) {
         return;
@@ -795,24 +794,18 @@ static void vhost_iommu_region_add(MemoryListener *listener,
     iommu_idx = memory_region_iommu_attrs_to_index(iommu_mr,
                                                    MEMTXATTRS_UNSPECIFIED);
     iommu_notifier_init(&iommu->n, vhost_iommu_unmap_notify,
-                        IOMMU_NOTIFIER_DEVIOTLB_UNMAP,
+                        dev->vdev->device_iotlb_enabled ?
+                            IOMMU_NOTIFIER_DEVIOTLB_UNMAP :
+                            IOMMU_NOTIFIER_UNMAP,
                         section->offset_within_region,
                         int128_get64(end),
                         iommu_idx);
     iommu->mr = section->mr;
     iommu->iommu_offset = section->offset_within_address_space -
                           section->offset_within_region;
     iommu->hdev = dev;
-    ret = memory_region_register_iommu_notifier(section->mr, &iommu->n, NULL);
-    if (ret) {
-        /*
-         * Some vIOMMUs do not support dev-iotlb yet.  If so, try to use the
-         * UNMAP legacy message
-         */
-        iommu->n.notifier_flags = IOMMU_NOTIFIER_UNMAP;
-        memory_region_register_iommu_notifier(section->mr, &iommu->n,
-                                              &error_fatal);
-    }
+    memory_region_register_iommu_notifier(section->mr, &iommu->n,
+                                          &error_fatal);
     QLIST_INSERT_HEAD(&dev->iommu_list, iommu, iommu_next);
     /* TODO: can replay help performance here? */
 }
@@ -840,6 +833,27 @@ static void vhost_iommu_region_del(MemoryListener *listener,
     }
 }
 
+void vhost_toggle_device_iotlb(VirtIODevice *vdev)
+{
+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
+    struct vhost_dev *dev;
+    struct vhost_iommu *iommu;
+
+    if (vdev->vhost_started) {
+        dev = vdc->get_vhost(vdev);
+    } else {
+        return;
+    }
+
+    QLIST_FOREACH(iommu, &dev->iommu_list, iommu_next) {
+        memory_region_unregister_iommu_notifier(iommu->mr, &iommu->n);
+        iommu->n.notifier_flags = vdev->device_iotlb_enabled ?
+                IOMMU_NOTIFIER_DEVIOTLB_UNMAP : IOMMU_NOTIFIER_UNMAP;
+        memory_region_register_iommu_notifier(iommu->mr, &iommu->n,
+                                              &error_fatal);
+    }
+}
+
 static int vhost_virtqueue_set_addr(struct vhost_dev *dev,
                                     struct vhost_virtqueue *vq,
                                     unsigned idx, bool enable_log)

diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
@@ -320,6 +320,7 @@ bool vhost_has_free_slot(void);
 int vhost_net_set_backend(struct vhost_dev *hdev,
                           struct vhost_vring_file *file);
 
+void vhost_toggle_device_iotlb(VirtIODevice *vdev);
 int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write);
 
 int vhost_virtqueue_start(struct vhost_dev *dev, struct VirtIODevice *vdev,