Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Pull virtio updates from Michael Tsirkin:
 "Several fixes, most notably fix for virtio on swiotlb systems"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  vhost: silence an unused-variable warning
  virtio: hint if callbacks surprisingly might sleep
  virtio-ccw: wire up ->bus_name callback
  s390/virtio: handle find on invalid queue gracefully
  virtio-ccw: diag 500 may return a negative cookie
  virtio_balloon: remove the unnecessary 0-initialization
  virtio-balloon: improve update_balloon_size_func
  virtio-blk: Consider virtio_max_dma_size() for maximum segment size
  virtio: Introduce virtio_max_dma_size()
  dma: Introduce dma_max_mapping_size()
  swiotlb: Add is_swiotlb_active() function
  swiotlb: Introduce swiotlb_max_mapping_size()

6 files changed, 35 insertions, 8 deletions

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index b16a887bbd02..4bc083b7c9b5 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -723,7 +723,7 @@ static int virtblk_probe(struct virtio_device *vdev)
 	struct request_queue *q;
 	int err, index;
 
-	u32 v, blk_size, sg_elems, opt_io_size;
+	u32 v, blk_size, max_size, sg_elems, opt_io_size;
 	u16 min_io_size;
 	u8 physical_block_exp, alignment_offset;
 
@@ -826,14 +826,16 @@ static int virtblk_probe(struct virtio_device *vdev)
 	/* No real sector limit. */
 	blk_queue_max_hw_sectors(q, -1U);
 
+	max_size = virtio_max_dma_size(vdev);
+
 	/* Host can optionally specify maximum segment size and number of
 	 * segments. */
 	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
 				   struct virtio_blk_config, size_max, &v);
 	if (!err)
-		blk_queue_max_segment_size(q, v);
-	else
-		blk_queue_max_segment_size(q, -1U);
+		max_size = min(max_size, v);
+
+	blk_queue_max_segment_size(q, max_size);
 
 	/* Host can optionally specify the block size of the device */
 	err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index ae1d56da671d..74c328321889 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -272,6 +272,8 @@ static void virtio_ccw_drop_indicators(struct virtio_ccw_device *vcdev)
 {
 	struct virtio_ccw_vq_info *info;
 
+	if (!vcdev->airq_info)
+		return;
 	list_for_each_entry(info, &vcdev->virtqueues, node)
 		drop_airq_indicator(info->vq, vcdev->airq_info);
 }
@@ -413,7 +415,7 @@ static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev,
 	ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_VQ_CONF);
 	if (ret)
 		return ret;
-	return vcdev->config_block->num;
+	return vcdev->config_block->num ?: -ENOENT;
 }
 
 static void virtio_ccw_del_vq(struct virtqueue *vq, struct ccw1 *ccw)
@@ -973,6 +975,13 @@ static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status)
 	kfree(ccw);
 }
 
+static const char *virtio_ccw_bus_name(struct virtio_device *vdev)
+{
+	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+
+	return dev_name(&vcdev->cdev->dev);
+}
+
 static const struct virtio_config_ops virtio_ccw_config_ops = {
 	.get_features = virtio_ccw_get_features,
 	.finalize_features = virtio_ccw_finalize_features,
@@ -983,6 +992,7 @@ static const struct virtio_config_ops virtio_ccw_config_ops = {
 	.reset = virtio_ccw_reset,
 	.find_vqs = virtio_ccw_find_vqs,
 	.del_vqs = virtio_ccw_del_vqs,
+	.bus_name = virtio_ccw_bus_name,
 };
 
 
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index a2e5dc7716e2..5ace833de746 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1188,7 +1188,7 @@ static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
 			 struct vring_used __user *used)
 
 {
-	size_t s = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
+	size_t s __maybe_unused = vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0;
 
 	return access_ok(desc, num * sizeof *desc) &&
 	       access_ok(avail,
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 59e36ef4920f..98b30f54342c 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -161,6 +161,7 @@ EXPORT_SYMBOL_GPL(virtio_config_enable);
 
 void virtio_add_status(struct virtio_device *dev, unsigned int status)
 {
+	might_sleep();
 	dev->config->set_status(dev, dev->config->get_status(dev) | status);
 }
 EXPORT_SYMBOL_GPL(virtio_add_status);
@@ -170,6 +171,7 @@ int virtio_finalize_features(struct virtio_device *dev)
 	int ret = dev->config->finalize_features(dev);
 	unsigned status;
 
+	might_sleep();
 	if (ret)
 		return ret;
 
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index fb12fe205f86..f19061b585a4 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -457,9 +457,12 @@ static void update_balloon_size_func(struct work_struct *work)
 			  update_balloon_size_work);
 	diff = towards_target(vb);
 
+	if (!diff)
+		return;
+
 	if (diff > 0)
 		diff -= fill_balloon(vb, diff);
-	else if (diff < 0)
+	else
 		diff += leak_balloon(vb, -diff);
 	update_balloon_size(vb);
 
@@ -922,7 +925,6 @@ static int virtballoon_probe(struct virtio_device *vdev)
 						  VIRTIO_BALLOON_CMD_ID_STOP);
 		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
 						  VIRTIO_BALLOON_CMD_ID_STOP);
-		vb->num_free_page_blocks = 0;
 		spin_lock_init(&vb->free_page_list_lock);
 		INIT_LIST_HEAD(&vb->free_page_list);
 		if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index a0b07c331255..18846afb39da 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -271,6 +271,17 @@ static bool vring_use_dma_api(struct virtio_device *vdev)
 	return false;
 }
 
+size_t virtio_max_dma_size(struct virtio_device *vdev)
+{
+	size_t max_segment_size = SIZE_MAX;
+
+	if (vring_use_dma_api(vdev))
+		max_segment_size = dma_max_mapping_size(&vdev->dev);
+
+	return max_segment_size;
+}
+EXPORT_SYMBOL_GPL(virtio_max_dma_size);
+
 static void *vring_alloc_queue(struct virtio_device *vdev, size_t size,
 			      dma_addr_t *dma_handle, gfp_t flag)
 {