Main excitement is a virtio_scsi fix for alloc holding spinlock on the abort

path, which I refuse to CC stable since (1) I discovered it myself, and
 (2) it's been there forever with no reports.
 
 Cheers,
 Rusty.
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Merge tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

Pull virtio updates from Rusty Russell:
 "Main excitement is a virtio_scsi fix for alloc holding spinlock on the
  abort path, which I refuse to CC stable since (1) I discovered it
  myself, and (2) it's been there forever with no reports"

* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  virtio_scsi: don't call virtqueue_add_sgs(... GFP_NOIO) holding spinlock.
  virtio-rng: fixes for device registration/unregistration
  virtio-rng: fix boot with virtio-rng device
  virtio-rng: support multiple virtio-rng devices
  virtio_ccw: introduce device_lost in virtio_ccw_device
  virtio: virtio_break_device() to mark all virtqueues broken.

drivers/char/hw_random/virtio-rng.c

@@ -25,88 +25,115 @@
 #include <linux/virtio_rng.h>
 #include <linux/module.h>
 
-static struct virtqueue *vq;
-static unsigned int data_avail;
-static DECLARE_COMPLETION(have_data);
-static bool busy;
+static DEFINE_IDA(rng_index_ida);
+
+struct virtrng_info {
+	struct virtio_device *vdev;
+	struct hwrng hwrng;
+	struct virtqueue *vq;
+	unsigned int data_avail;
+	struct completion have_data;
+	bool busy;
+	char name[25];
+	int index;
+};
 
 static void random_recv_done(struct virtqueue *vq)
 {
+	struct virtrng_info *vi = vq->vdev->priv;
+
 	/* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
-	if (!virtqueue_get_buf(vq, &data_avail))
+	if (!virtqueue_get_buf(vi->vq, &vi->data_avail))
 		return;
 
-	complete(&have_data);
+	complete(&vi->have_data);
 }
 
 /* The host will fill any buffer we give it with sweet, sweet randomness. */
-static void register_buffer(u8 *buf, size_t size)
+static void register_buffer(struct virtrng_info *vi, u8 *buf, size_t size)
 {
 	struct scatterlist sg;
 
 	sg_init_one(&sg, buf, size);
 
 	/* There should always be room for one buffer. */
-	virtqueue_add_inbuf(vq, &sg, 1, buf, GFP_KERNEL);
+	virtqueue_add_inbuf(vi->vq, &sg, 1, buf, GFP_KERNEL);
 
-	virtqueue_kick(vq);
+	virtqueue_kick(vi->vq);
 }
 
 static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait)
 {
 	int ret;
+	struct virtrng_info *vi = (struct virtrng_info *)rng->priv;
 
-	if (!busy) {
-		busy = true;
-		init_completion(&have_data);
-		register_buffer(buf, size);
+	if (!vi->busy) {
+		vi->busy = true;
+		init_completion(&vi->have_data);
+		register_buffer(vi, buf, size);
 	}
 
 	if (!wait)
 		return 0;
 
-	ret = wait_for_completion_killable(&have_data);
+	ret = wait_for_completion_killable(&vi->have_data);
 	if (ret < 0)
 		return ret;
 
-	busy = false;
+	vi->busy = false;
 
-	return data_avail;
+	return vi->data_avail;
 }
 
 static void virtio_cleanup(struct hwrng *rng)
 {
-	if (busy)
-		wait_for_completion(&have_data);
+	struct virtrng_info *vi = (struct virtrng_info *)rng->priv;
+
+	if (vi->busy)
+		wait_for_completion(&vi->have_data);
 }
 
-
-static struct hwrng virtio_hwrng = {
-	.name		= "virtio",
-	.cleanup	= virtio_cleanup,
-	.read		= virtio_read,
-};
-
 static int probe_common(struct virtio_device *vdev)
 {
-	int err;
+	int err, index;
+	struct virtrng_info *vi = NULL;
 
-	if (vq) {
-		/* We only support one device for now */
-		return -EBUSY;
+	vi = kzalloc(sizeof(struct virtrng_info), GFP_KERNEL);
+	if (!vi)
+		return -ENOMEM;
+
+	vi->index = index = ida_simple_get(&rng_index_ida, 0, 0, GFP_KERNEL);
+	if (index < 0) {
+		kfree(vi);
+		return index;
 	}
+	sprintf(vi->name, "virtio_rng.%d", index);
+	init_completion(&vi->have_data);
+
+	vi->hwrng = (struct hwrng) {
+		.read = virtio_read,
+		.cleanup = virtio_cleanup,
+		.priv = (unsigned long)vi,
+		.name = vi->name,
+	};
+	vdev->priv = vi;
+
 	/* We expect a single virtqueue. */
-	vq = virtio_find_single_vq(vdev, random_recv_done, "input");
-	if (IS_ERR(vq)) {
-		err = PTR_ERR(vq);
-		vq = NULL;
+	vi->vq = virtio_find_single_vq(vdev, random_recv_done, "input");
+	if (IS_ERR(vi->vq)) {
+		err = PTR_ERR(vi->vq);
+		vi->vq = NULL;
+		kfree(vi);
+		ida_simple_remove(&rng_index_ida, index);
 		return err;
 	}
 
-	err = hwrng_register(&virtio_hwrng);
+	err = hwrng_register(&vi->hwrng);
 	if (err) {
 		vdev->config->del_vqs(vdev);
-		vq = NULL;
+		vi->vq = NULL;
+		kfree(vi);
+		ida_simple_remove(&rng_index_ida, index);
 		return err;
 	}
 
@@ -115,11 +142,13 @@ static int probe_common(struct virtio_device *vdev)
 
 static void remove_common(struct virtio_device *vdev)
 {
+	struct virtrng_info *vi = vdev->priv;
 	vdev->config->reset(vdev);
-	busy = false;
-	hwrng_unregister(&virtio_hwrng);
+	vi->busy = false;
+	hwrng_unregister(&vi->hwrng);
 	vdev->config->del_vqs(vdev);
-	vq = NULL;
+	ida_simple_remove(&rng_index_ida, vi->index);
+	kfree(vi);
 }
 
 static int virtrng_probe(struct virtio_device *vdev)

drivers/s390/kvm/virtio_ccw.c

@@ -27,6 +27,7 @@
 #include <linux/module.h>
 #include <linux/io.h>
 #include <linux/kvm_para.h>
+#include <linux/notifier.h>
 #include <asm/setup.h>
 #include <asm/irq.h>
 #include <asm/cio.h>
@@ -62,6 +63,7 @@ struct virtio_ccw_device {
 	struct vq_config_block *config_block;
 	bool is_thinint;
 	bool going_away;
+	bool device_lost;
 	void *airq_info;
 };
 
@@ -1010,11 +1012,14 @@ static void virtio_ccw_remove(struct ccw_device *cdev)
 	unsigned long flags;
 	struct virtio_ccw_device *vcdev = virtio_grab_drvdata(cdev);
 
-	if (vcdev && cdev->online)
+	if (vcdev && cdev->online) {
+		if (vcdev->device_lost)
+			virtio_break_device(&vcdev->vdev);
 		unregister_virtio_device(&vcdev->vdev);
-	spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
-	dev_set_drvdata(&cdev->dev, NULL);
-	spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
+		spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
+		dev_set_drvdata(&cdev->dev, NULL);
+		spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
+	}
 	cdev->handler = NULL;
 }
 
@@ -1023,12 +1028,14 @@ static int virtio_ccw_offline(struct ccw_device *cdev)
 	unsigned long flags;
 	struct virtio_ccw_device *vcdev = virtio_grab_drvdata(cdev);
 
-	if (vcdev) {
-		unregister_virtio_device(&vcdev->vdev);
-		spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
-		dev_set_drvdata(&cdev->dev, NULL);
-		spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
-	}
+	if (!vcdev)
+		return 0;
+	if (vcdev->device_lost)
+		virtio_break_device(&vcdev->vdev);
+	unregister_virtio_device(&vcdev->vdev);
+	spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
+	dev_set_drvdata(&cdev->dev, NULL);
+	spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
 	return 0;
 }
 
@@ -1096,8 +1103,26 @@ out_free:
 
 static int virtio_ccw_cio_notify(struct ccw_device *cdev, int event)
 {
-	/* TODO: Check whether we need special handling here. */
-	return 0;
+	int rc;
+	struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev);
+
+	/*
+	 * Make sure vcdev is set
+	 * i.e. set_offline/remove callback not already running
+	 */
+	if (!vcdev)
+		return NOTIFY_DONE;
+
+	switch (event) {
+	case CIO_GONE:
+		vcdev->device_lost = true;
+		rc = NOTIFY_DONE;
+		break;
+	default:
+		rc = NOTIFY_DONE;
+		break;
+	}
+	return rc;
 }
 
 static struct ccw_device_id virtio_ids[] = {

drivers/scsi/virtio_scsi.c

@@ -393,11 +393,10 @@ static void virtscsi_event_done(struct virtqueue *vq)
  * @cmd		: command structure
  * @req_size	: size of the request buffer
  * @resp_size	: size of the response buffer
- * @gfp	: flags to use for memory allocations
  */
 static int virtscsi_add_cmd(struct virtqueue *vq,
 			    struct virtio_scsi_cmd *cmd,
-			    size_t req_size, size_t resp_size, gfp_t gfp)
+			    size_t req_size, size_t resp_size)
 {
 	struct scsi_cmnd *sc = cmd->sc;
 	struct scatterlist *sgs[4], req, resp;
@@ -429,19 +428,19 @@ static int virtscsi_add_cmd(struct virtqueue *vq,
 	if (in)
 		sgs[out_num + in_num++] = in->sgl;
 
-	return virtqueue_add_sgs(vq, sgs, out_num, in_num, cmd, gfp);
+	return virtqueue_add_sgs(vq, sgs, out_num, in_num, cmd, GFP_ATOMIC);
 }
 
 static int virtscsi_kick_cmd(struct virtio_scsi_vq *vq,
 			     struct virtio_scsi_cmd *cmd,
-			     size_t req_size, size_t resp_size, gfp_t gfp)
+			     size_t req_size, size_t resp_size)
 {
 	unsigned long flags;
 	int err;
 	bool needs_kick = false;
 
 	spin_lock_irqsave(&vq->vq_lock, flags);
-	err = virtscsi_add_cmd(vq->vq, cmd, req_size, resp_size, gfp);
+	err = virtscsi_add_cmd(vq->vq, cmd, req_size, resp_size);
 	if (!err)
 		needs_kick = virtqueue_kick_prepare(vq->vq);
 
@@ -484,8 +483,7 @@ static int virtscsi_queuecommand(struct virtio_scsi *vscsi,
 	memcpy(cmd->req.cmd.cdb, sc->cmnd, sc->cmd_len);
 
 	if (virtscsi_kick_cmd(req_vq, cmd,
-			      sizeof cmd->req.cmd, sizeof cmd->resp.cmd,
-			      GFP_ATOMIC) != 0)
+			      sizeof cmd->req.cmd, sizeof cmd->resp.cmd) != 0)
 		return SCSI_MLQUEUE_HOST_BUSY;
 	return 0;
 }
@@ -542,8 +540,7 @@ static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd)
 
 	cmd->comp = ∁
 	if (virtscsi_kick_cmd(&vscsi->ctrl_vq, cmd,
-			      sizeof cmd->req.tmf, sizeof cmd->resp.tmf,
-			      GFP_NOIO) < 0)
+			      sizeof cmd->req.tmf, sizeof cmd->resp.tmf) < 0)
 		goto out;
 
 	wait_for_completion(&comp);

drivers/virtio/virtio_ring.c

@@ -865,4 +865,19 @@ bool virtqueue_is_broken(struct virtqueue *_vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_is_broken);
 
+/*
+ * This should prevent the device from being used, allowing drivers to
+ * recover.  You may need to grab appropriate locks to flush.
+ */
+void virtio_break_device(struct virtio_device *dev)
+{
+	struct virtqueue *_vq;
+
+	list_for_each_entry(_vq, &dev->vqs, list) {
+		struct vring_virtqueue *vq = to_vvq(_vq);
+		vq->broken = true;
+	}
+}
+EXPORT_SYMBOL_GPL(virtio_break_device);
+
 MODULE_LICENSE("GPL");

include/linux/virtio.h

@@ -106,6 +106,8 @@ static inline struct virtio_device *dev_to_virtio(struct device *_dev)
 int register_virtio_device(struct virtio_device *dev);
 void unregister_virtio_device(struct virtio_device *dev);
 
+void virtio_break_device(struct virtio_device *dev);
+
 /**
  * virtio_driver - operations for a virtio I/O driver
  * @driver: underlying device driver (populate name and owner).