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Date: Thu, 3 Mar 2016 18:46:59 +0800
From: Liang Li <liang.z.li@...el.com>
To: mst@...hat.com, linux-kernel@...r.kernel.org
Cc: akpm@...ux-foundation.org, pbonzini@...hat.com, rth@...ddle.net,
ehabkost@...hat.com, quintela@...hat.com, amit.shah@...hat.com,
qemu-devel@...gnu.org, linux-mm@...ck.org,
virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
dgilbert@...hat.com, Liang Li <liang.z.li@...el.com>
Subject: [RFC kernel 2/2] virtio-balloon: extend balloon driver to support a new feature
Extend the virio balloon to support the new feature
VIRTIO_BALLOON_F_GET_FREE_PAGES, so that we can use it to send the
free pages information from guest to QEMU, and then optimize the
live migration process.
Signed-off-by: Liang Li <liang.z.li@...el.com>
---
drivers/virtio/virtio_balloon.c | 106 ++++++++++++++++++++++++++++++++++--
include/uapi/linux/virtio_balloon.h | 1 +
2 files changed, 102 insertions(+), 5 deletions(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 0c3691f..7461d3e 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -45,9 +45,18 @@ static int oom_pages = OOM_VBALLOON_DEFAULT_PAGES;
module_param(oom_pages, int, S_IRUSR | S_IWUSR);
MODULE_PARM_DESC(oom_pages, "pages to free on OOM");
+extern void get_free_pages(unsigned long *free_page_bitmap,
+ unsigned long *free_pages_num,
+ unsigned long lowmem);
+extern unsigned long get_total_pages_count(unsigned long lowmem);
+
+struct mem_layout {
+ unsigned long low_mem;
+};
+
struct virtio_balloon {
struct virtio_device *vdev;
- struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
+ struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_pages_vq;
/* Where the ballooning thread waits for config to change. */
wait_queue_head_t config_change;
@@ -75,6 +84,11 @@ struct virtio_balloon {
unsigned int num_pfns;
u32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
+ unsigned long *free_pages;
+ unsigned long free_pages_len;
+ unsigned long free_pages_num;
+ struct mem_layout mem_config;
+
/* Memory statistics */
int need_stats_update;
struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
@@ -245,6 +259,34 @@ static void update_balloon_stats(struct virtio_balloon *vb)
pages_to_bytes(i.totalram));
}
+static void update_free_pages_stats(struct virtio_balloon *vb)
+{
+ unsigned long total_page_count, bitmap_bytes;
+
+ total_page_count = get_total_pages_count(vb->mem_config.low_mem);
+ bitmap_bytes = ALIGN(total_page_count, BITS_PER_LONG) / 8;
+
+ if (!vb->free_pages)
+ vb->free_pages = kzalloc(bitmap_bytes, GFP_KERNEL);
+ else {
+ if (bitmap_bytes < vb->free_pages_len)
+ memset(vb->free_pages, 0, bitmap_bytes);
+ else {
+ kfree(vb->free_pages);
+ vb->free_pages = kzalloc(bitmap_bytes, GFP_KERNEL);
+ }
+ }
+ if (!vb->free_pages) {
+ vb->free_pages_len = 0;
+ vb->free_pages_num = 0;
+ return;
+ }
+
+ vb->free_pages_len = bitmap_bytes;
+ get_free_pages(vb->free_pages, &vb->free_pages_num,
+ vb->mem_config.low_mem);
+}
+
/*
* While most virtqueues communicate guest-initiated requests to the hypervisor,
* the stats queue operates in reverse. The driver initializes the virtqueue
@@ -278,6 +320,39 @@ static void stats_handle_request(struct virtio_balloon *vb)
virtqueue_kick(vq);
}
+static void free_pages_handle_rq(struct virtio_balloon *vb)
+{
+ struct virtqueue *vq;
+ struct scatterlist sg[3];
+ unsigned int len;
+ struct mem_layout *ptr_mem_layout;
+ struct scatterlist sg_in;
+
+ vq = vb->free_pages_vq;
+ ptr_mem_layout = virtqueue_get_buf(vq, &len);
+
+ if (!ptr_mem_layout)
+ return;
+ update_free_pages_stats(vb);
+ sg_init_table(sg, 3);
+ sg_set_buf(&sg[0], &(vb->free_pages_num), sizeof(vb->free_pages_num));
+ sg_set_buf(&sg[1], &(vb->free_pages_len), sizeof(vb->free_pages_len));
+ sg_set_buf(&sg[2], vb->free_pages, vb->free_pages_len);
+
+ sg_init_one(&sg_in, &vb->mem_config, sizeof(vb->mem_config));
+
+ virtqueue_add_outbuf(vq, &sg[0], 3, vb, GFP_KERNEL);
+ virtqueue_add_inbuf(vq, &sg_in, 1, &vb->mem_config, GFP_KERNEL);
+ virtqueue_kick(vq);
+}
+
+static void free_pages_rq(struct virtqueue *vq)
+{
+ struct virtio_balloon *vb = vq->vdev->priv;
+
+ free_pages_handle_rq(vb);
+}
+
static void virtballoon_changed(struct virtio_device *vdev)
{
struct virtio_balloon *vb = vdev->priv;
@@ -386,16 +461,22 @@ static int balloon(void *_vballoon)
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" };
+ struct virtqueue *vqs[4];
+ vq_callback_t *callbacks[] = { balloon_ack, balloon_ack,
+ stats_request, free_pages_rq };
+ const char *names[] = { "inflate", "deflate", "stats", "free_pages" };
int err, nvqs;
/*
* We expect two virtqueues: inflate and deflate, and
* optionally stat.
*/
- nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_GET_FREE_PAGES))
+ nvqs = 4;
+ else
+ nvqs = virtio_has_feature(vb->vdev,
+ VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
+
err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names);
if (err)
return err;
@@ -416,6 +497,16 @@ static int init_vqs(struct virtio_balloon *vb)
BUG();
virtqueue_kick(vb->stats_vq);
}
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_GET_FREE_PAGES)) {
+ struct scatterlist sg_in;
+
+ vb->free_pages_vq = vqs[3];
+ sg_init_one(&sg_in, &vb->mem_config, sizeof(vb->mem_config));
+ if (virtqueue_add_inbuf(vb->free_pages_vq, &sg_in, 1,
+ &vb->mem_config, GFP_KERNEL) < 0)
+ BUG();
+ virtqueue_kick(vb->free_pages_vq);
+ }
return 0;
}
@@ -505,6 +596,9 @@ static int virtballoon_probe(struct virtio_device *vdev)
init_waitqueue_head(&vb->acked);
vb->vdev = vdev;
vb->need_stats_update = 0;
+ vb->free_pages_num = 0;
+ vb->free_pages_len = 0;
+ vb->free_pages = NULL;
balloon_devinfo_init(&vb->vb_dev_info);
#ifdef CONFIG_BALLOON_COMPACTION
@@ -561,6 +655,7 @@ static void virtballoon_remove(struct virtio_device *vdev)
unregister_oom_notifier(&vb->nb);
kthread_stop(vb->thread);
remove_common(vb);
+ kfree(vb->free_pages);
kfree(vb);
}
@@ -599,6 +694,7 @@ static unsigned int features[] = {
VIRTIO_BALLOON_F_MUST_TELL_HOST,
VIRTIO_BALLOON_F_STATS_VQ,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
+ VIRTIO_BALLOON_F_GET_FREE_PAGES,
};
static struct virtio_driver virtio_balloon_driver = {
diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index d7f1cbc..54aaf20 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -34,6 +34,7 @@
#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
#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_GET_FREE_PAGES 3 /* Get free pages bitmap */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
--
1.8.3.1
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