4.20-stable review patch. If anyone has any objections, please let me know.
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From: Wei Wang wei.w.wang@intel.com
commit bf4dc0b2beebfd9338df7c0bcf473b356f67cf66 upstream.
virtio-ccw has deadlock issues with reading the config space inside the interrupt context, so we tweak the virtballoon_changed implementation by moving the config read operations into the related workqueue contexts. The config_read_bitmap is used as a flag to the workqueue callbacks about the related config fields that need to be read.
The cmd_id_received is also renamed to cmd_id_received_cache, and the value should be obtained via virtio_balloon_cmd_id_received.
Reported-by: Christian Borntraeger borntraeger@de.ibm.com Signed-off-by: Wei Wang wei.w.wang@intel.com Reviewed-by: Cornelia Huck cohuck@redhat.com Reviewed-by: Halil Pasic pasic@linux.ibm.com Signed-off-by: Michael S. Tsirkin mst@redhat.com Cc: stable@vger.kernel.org Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT") Tested-by: Christian Borntraeger borntraeger@de.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/virtio/virtio_balloon.c | 98 ++++++++++++++++++++++++++-------------- 1 file changed, 65 insertions(+), 33 deletions(-)
--- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -61,6 +61,10 @@ enum virtio_balloon_vq { VIRTIO_BALLOON_VQ_MAX };
+enum virtio_balloon_config_read { + VIRTIO_BALLOON_CONFIG_READ_CMD_ID = 0, +}; + struct virtio_balloon { struct virtio_device *vdev; struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; @@ -77,14 +81,20 @@ struct virtio_balloon { /* Prevent updating balloon when it is being canceled. */ spinlock_t stop_update_lock; bool stop_update; + /* Bitmap to indicate if reading the related config fields are needed */ + unsigned long config_read_bitmap;
/* The list of allocated free pages, waiting to be given back to mm */ struct list_head free_page_list; spinlock_t free_page_list_lock; /* The number of free page blocks on the above list */ unsigned long num_free_page_blocks; - /* The cmd id received from host */ - u32 cmd_id_received; + /* + * The cmd id received from host. + * Read it via virtio_balloon_cmd_id_received to get the latest value + * sent from host. + */ + u32 cmd_id_received_cache; /* The cmd id that is actively in use */ __virtio32 cmd_id_active; /* Buffer to store the stop sign */ @@ -390,37 +400,31 @@ static unsigned long return_free_pages_t return num_returned; }
+static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb) +{ + if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) + return; + + /* No need to queue the work if the bit was already set. */ + if (test_and_set_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID, + &vb->config_read_bitmap)) + return; + + queue_work(vb->balloon_wq, &vb->report_free_page_work); +} + static void virtballoon_changed(struct virtio_device *vdev) { struct virtio_balloon *vb = vdev->priv; unsigned long flags; - s64 diff = towards_target(vb);
- if (diff) { - spin_lock_irqsave(&vb->stop_update_lock, flags); - if (!vb->stop_update) - queue_work(system_freezable_wq, - &vb->update_balloon_size_work); - spin_unlock_irqrestore(&vb->stop_update_lock, flags); - } - - if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { - virtio_cread(vdev, struct virtio_balloon_config, - free_page_report_cmd_id, &vb->cmd_id_received); - if (vb->cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) { - /* Pass ULONG_MAX to give back all the free pages */ - return_free_pages_to_mm(vb, ULONG_MAX); - } else if (vb->cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP && - vb->cmd_id_received != - virtio32_to_cpu(vdev, vb->cmd_id_active)) { - spin_lock_irqsave(&vb->stop_update_lock, flags); - if (!vb->stop_update) { - queue_work(vb->balloon_wq, - &vb->report_free_page_work); - } - spin_unlock_irqrestore(&vb->stop_update_lock, flags); - } + spin_lock_irqsave(&vb->stop_update_lock, flags); + if (!vb->stop_update) { + queue_work(system_freezable_wq, + &vb->update_balloon_size_work); + virtio_balloon_queue_free_page_work(vb); } + spin_unlock_irqrestore(&vb->stop_update_lock, flags); }
static void update_balloon_size(struct virtio_balloon *vb) @@ -527,6 +531,17 @@ static int init_vqs(struct virtio_balloo return 0; }
+static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb) +{ + if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID, + &vb->config_read_bitmap)) + virtio_cread(vb->vdev, struct virtio_balloon_config, + free_page_report_cmd_id, + &vb->cmd_id_received_cache); + + return vb->cmd_id_received_cache; +} + static int send_cmd_id_start(struct virtio_balloon *vb) { struct scatterlist sg; @@ -537,7 +552,8 @@ static int send_cmd_id_start(struct virt while (virtqueue_get_buf(vq, &unused)) ;
- vb->cmd_id_active = cpu_to_virtio32(vb->vdev, vb->cmd_id_received); + vb->cmd_id_active = virtio32_to_cpu(vb->vdev, + virtio_balloon_cmd_id_received(vb)); sg_init_one(&sg, &vb->cmd_id_active, sizeof(vb->cmd_id_active)); err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_active, GFP_KERNEL); if (!err) @@ -620,7 +636,8 @@ static int send_free_pages(struct virtio * stop the reporting. */ cmd_id_active = virtio32_to_cpu(vb->vdev, vb->cmd_id_active); - if (cmd_id_active != vb->cmd_id_received) + if (unlikely(cmd_id_active != + virtio_balloon_cmd_id_received(vb))) break;
/* @@ -637,11 +654,9 @@ static int send_free_pages(struct virtio return 0; }
-static void report_free_page_func(struct work_struct *work) +static void virtio_balloon_report_free_page(struct virtio_balloon *vb) { int err; - struct virtio_balloon *vb = container_of(work, struct virtio_balloon, - report_free_page_work); struct device *dev = &vb->vdev->dev;
/* Start by sending the received cmd id to host with an outbuf. */ @@ -659,6 +674,23 @@ static void report_free_page_func(struct dev_err(dev, "Failed to send a stop id, err = %d\n", err); }
+static void report_free_page_func(struct work_struct *work) +{ + struct virtio_balloon *vb = container_of(work, struct virtio_balloon, + report_free_page_work); + u32 cmd_id_received; + + cmd_id_received = virtio_balloon_cmd_id_received(vb); + if (cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) { + /* Pass ULONG_MAX to give back all the free pages */ + return_free_pages_to_mm(vb, ULONG_MAX); + } else if (cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP && + cmd_id_received != + virtio32_to_cpu(vb->vdev, vb->cmd_id_active)) { + virtio_balloon_report_free_page(vb); + } +} + #ifdef CONFIG_BALLOON_COMPACTION /* * virtballoon_migratepage - perform the balloon page migration on behalf of @@ -885,7 +917,7 @@ static int virtballoon_probe(struct virt goto out_del_vqs; } INIT_WORK(&vb->report_free_page_work, report_free_page_func); - vb->cmd_id_received = VIRTIO_BALLOON_CMD_ID_STOP; + vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP; vb->cmd_id_active = cpu_to_virtio32(vb->vdev, VIRTIO_BALLOON_CMD_ID_STOP); vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,