[PATCH v14 5/5] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_VQ

Wei Wang
2017-08-17T03:38:39Z

Add a new vq to report hints of guest free pages to the host.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Liang Li <liang.z.li@intel.com>
---
drivers/virtio/virtio_balloon.c | 167 +++++++++++++++++++++++++++++++-----
include/uapi/linux/virtio_balloon.h | 1 +
2 files changed, 147 insertions(+), 21 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 72041b4..e6755bc 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -54,11 +54,12 @@ static struct vfsmount *balloon_mnt;

struct virtio_balloon {
struct virtio_device *vdev;
- struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
+ struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;

/* The balloon servicing is delegated to a freezable workqueue. */
struct work_struct update_balloon_stats_work;
struct work_struct update_balloon_size_work;
+ struct work_struct report_free_page_work;

/* Prevent updating balloon when it is being canceled. */
spinlock_t stop_update_lock;
@@ -90,6 +91,13 @@ struct virtio_balloon {
/* Memory statistics */
struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];

+ /*
+ * Used by the device and driver to signal each other.
+ * device->driver: start the free page report.
+ * driver->device: end the free page report.
+ */
+ __virtio32 report_free_page_signal;
+
/* To register callback in oom notifier call chain */
struct notifier_block nb;
};
@@ -174,6 +182,17 @@ static void send_balloon_page_sg(struct virtio_balloon *vb,
} while (unlikely(ret == -ENOSPC));
}

+static void send_free_page_sg(struct virtqueue *vq, void *addr, uint32_t size)
+{
+ unsigned int len;
+
+ add_one_sg(vq, addr, size);
+ virtqueue_kick(vq);
+ /* Release entries if there are */
+ while (virtqueue_get_buf(vq, &len))
+ ;
+}
+
/*
* Send balloon pages in sgs to host. The balloon pages are recorded in the
* page xbitmap. Each bit in the bitmap corresponds to a page of PAGE_SIZE.
@@ -511,42 +530,143 @@ static void update_balloon_size_func(struct work_struct *work)
queue_work(system_freezable_wq, work);
}

+static void virtio_balloon_send_free_pages(void *opaque, unsigned long pfn,
+ unsigned long nr_pages)
+{
+ struct virtio_balloon *vb = (struct virtio_balloon *)opaque;
+ void *addr = (void *)pfn_to_kaddr(pfn);
+ uint32_t len = nr_pages << PAGE_SHIFT;
+
+ send_free_page_sg(vb->free_page_vq, addr, len);
+}
+
+static void report_free_page_completion(struct virtio_balloon *vb)
+{
+ struct virtqueue *vq = vb->free_page_vq;
+ struct scatterlist sg;
+ unsigned int len;
+ int ret;
+
+ sg_init_one(&sg, &vb->report_free_page_signal, sizeof(__virtio32));
+retry:
+ ret = virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
+ virtqueue_kick(vq);
+ if (unlikely(ret == -ENOSPC)) {
+ wait_event(vb->acked, virtqueue_get_buf(vq, &len));
+ goto retry;
+ }
+}
+
+static void report_free_page(struct work_struct *work)
+{
+ struct virtio_balloon *vb;
+
+ vb = container_of(work, struct virtio_balloon, report_free_page_work);
+ walk_free_mem_block(vb, 0, &virtio_balloon_send_free_pages);
+ report_free_page_completion(vb);
+}
+
+static void free_page_request(struct virtqueue *vq)
+{
+ struct virtio_balloon *vb = vq->vdev->priv;
+
+ queue_work(system_freezable_wq, &vb->report_free_page_work);
+}
+
static int init_vqs(struct virtio_balloon *vb)
{
- struct virtqueue *vqs[3];
- vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
- static const char * const names[] = { "inflate", "deflate", "stats" };
- int err, nvqs;
+ struct virtqueue **vqs;
+ vq_callback_t **callbacks;
+ const char **names;
+ struct scatterlist sg;
+ int i, nvqs, err = -ENOMEM;
+
+ /* Inflateq and deflateq are used unconditionally */
+ nvqs = 2;
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ))
+ nvqs++;
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ))
+ nvqs++;
+
+ /* Allocate space for find_vqs parameters */
+ vqs = kcalloc(nvqs, sizeof(*vqs), GFP_KERNEL);
+ if (!vqs)
+ goto err_vq;
+ callbacks = kmalloc_array(nvqs, sizeof(*callbacks), GFP_KERNEL);
+ if (!callbacks)
+ goto err_callback;
+ names = kmalloc_array(nvqs, sizeof(*names), GFP_KERNEL);
+ if (!names)
+ goto err_names;
+
+ callbacks[0] = balloon_ack;
+ names[0] = "inflate";
+ callbacks[1] = balloon_ack;
+ names[1] = "deflate";
+
+ i = 2;
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
+ callbacks[i] = stats_request;
+ names[i] = "stats";
+ i++;
+ }

- /*
- * We expect two virtqueues: inflate and deflate, and
- * optionally stat.
- */
- nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
- err = virtio_find_vqs(vb->vdev, nvqs, vqs, callbacks, names, NULL);
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ)) {
+ callbacks[i] = free_page_request;
+ names[i] = "free_page_vq";
+ }
+
+ err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names,
+ NULL, NULL);
if (err)
- return err;
+ goto err_find;

vb->inflate_vq = vqs[0];
vb->deflate_vq = vqs[1];
+ i = 2;
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
- struct scatterlist sg;
- unsigned int num_stats;
- vb->stats_vq = vqs[2];
-
+ vb->stats_vq = vqs[i++];
/*
* Prime this virtqueue with one buffer so the hypervisor can
* use it to signal us later (it can't be broken yet!).
*/
- num_stats = update_balloon_stats(vb);
-
- sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
+ sg_init_one(&sg, vb->stats, sizeof(vb->stats));
if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL)
- < 0)
- BUG();
+ < 0) {
+ dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n",
+ __func__);
+ goto err_find;
+ }
virtqueue_kick(vb->stats_vq);
}
+
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ)) {
+ vb->free_page_vq = vqs[i];
+ vb->report_free_page_signal = 0;
+ sg_init_one(&sg, &vb->report_free_page_signal,
+ sizeof(__virtio32));
+ if (virtqueue_add_outbuf(vb->free_page_vq, &sg, 1, vb,
+ GFP_KERNEL) < 0) {
+ dev_warn(&vb->vdev->dev, "%s: add signal buf failed\n",
+ __func__);
+ goto err_find;
+ }
+ virtqueue_kick(vb->free_page_vq);
+ }
+
+ kfree(names);
+ kfree(callbacks);
+ kfree(vqs);
return 0;
+
+err_find:
+ kfree(names);
+err_names:
+ kfree(callbacks);
+err_callback:
+ kfree(vqs);
+err_vq:
+ return err;
}

#ifdef CONFIG_BALLOON_COMPACTION
@@ -675,6 +795,9 @@ static int virtballoon_probe(struct virtio_device *vdev)
if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_SG))
xb_init(&vb->page_xb);

+ if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ))
+ INIT_WORK(&vb->report_free_page_work, report_free_page);
+
vb->nb.notifier_call = virtballoon_oom_notify;
vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
err = register_oom_notifier(&vb->nb);
@@ -739,6 +862,7 @@ static void virtballoon_remove(struct virtio_device *vdev)
spin_unlock_irq(&vb->stop_update_lock);
cancel_work_sync(&vb->update_balloon_size_work);
cancel_work_sync(&vb->update_balloon_stats_work);
+ cancel_work_sync(&vb->report_free_page_work);

remove_common(vb);
#ifdef CONFIG_BALLOON_COMPACTION
@@ -792,6 +916,7 @@ static unsigned int features[] = {
VIRTIO_BALLOON_F_STATS_VQ,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
VIRTIO_BALLOON_F_SG,
+ VIRTIO_BALLOON_F_FREE_PAGE_VQ,
};

static struct virtio_driver virtio_balloon_driver = {
diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index 37780a7..8214f84 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -35,6 +35,7 @@
#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
#define VIRTIO_BALLOON_F_SG 3 /* Use sg instead of PFN lists */
+#define VIRTIO_BALLOON_F_FREE_PAGE_VQ 4 /* Virtqueue to report free pages */

/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
--
2.7.4