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virtio-balloon: tweak config_changed implementation 

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: 86a559787e ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Wei Wang 2019-01-07 15:01:04 +08:00 committed by Michael S. Tsirkin
parent a229989d97
commit bf4dc0b2be
1 changed files with 65 additions and 33 deletions
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98
drivers/virtio/virtio_balloon.c
View File

@ -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_to_mm(struct virtio_balloon *vb,
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_balloon *vb)
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 virtio_balloon *vb)
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_balloon *vb)
* 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_balloon *vb)
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 work_struct *work)
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 virtio_device *vdev)
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,