Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the
host. If it is available and page_hinting_flag is set to true, page_hinting
is enabled and its callbacks are configured along with the max_pages count
which indicates the maximum number of pages that can be isolated and hinted
at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are
reported. To prevent any false OOM max_pages count is set to 16.
By default page_hinting feature is enabled and gets loaded as soon
as the virtio-balloon driver is loaded. However, it could be disabled
by writing the page_hinting_flag which is a virtio-balloon parameter.
Signed-off-by: Nitesh Narayan Lal <nitesh@xxxxxxxxxx>
---
drivers/virtio/virtio_balloon.c | 112 +++++++++++++++++++++++++++-
include/uapi/linux/virtio_balloon.h | 14 ++++
2 files changed, 125 insertions(+), 1 deletion(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index f19061b585a4..40f09ea31643 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -31,6 +31,7 @@
#include <linux/mm.h>
#include <linux/mount.h>
#include <linux/magic.h>
+#include <linux/page_hinting.h>
/*
* Balloon device works in 4K page units. So each page is pointed to by
@@ -48,6 +49,7 @@
/* The size of a free page block in bytes */
#define VIRTIO_BALLOON_FREE_PAGE_SIZE \
(1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT))
+#define VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES 16
#ifdef CONFIG_BALLOON_COMPACTION
static struct vfsmount *balloon_mnt;
@@ -58,6 +60,7 @@ enum virtio_balloon_vq {
VIRTIO_BALLOON_VQ_DEFLATE,
VIRTIO_BALLOON_VQ_STATS,
VIRTIO_BALLOON_VQ_FREE_PAGE,
+ VIRTIO_BALLOON_VQ_HINTING,
VIRTIO_BALLOON_VQ_MAX
};
@@ -67,7 +70,8 @@ enum virtio_balloon_config_read {
struct virtio_balloon {
struct virtio_device *vdev;
- struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
+ struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq,
+ *hinting_vq;
/* Balloon's own wq for cpu-intensive work items */
struct workqueue_struct *balloon_wq;
@@ -125,6 +129,9 @@ struct virtio_balloon {
/* To register a shrinker to shrink memory upon memory pressure */
struct shrinker shrinker;
+
+ /* object pointing at the array of isolated pages ready for hinting */
+ struct hinting_data *hinting_arr;
};
static struct virtio_device_id id_table[] = {
@@ -132,6 +139,85 @@ static struct virtio_device_id id_table[] = {
{ 0 },
};
+#ifdef CONFIG_PAGE_HINTING
+struct virtio_balloon *hvb;
+bool page_hinting_flag = true;
+module_param(page_hinting_flag, bool, 0444);
+MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting");
+
+static bool virtqueue_kick_sync(struct virtqueue *vq)
+{
+ u32 len;
+
+ if (likely(virtqueue_kick(vq))) {
+ while (!virtqueue_get_buf(vq, &len) &&
+ !virtqueue_is_broken(vq))
+ cpu_relax();
+ return true;
+ }
+ return false;
+}
+
+static void page_hinting_report(int entries)
+{
+ struct scatterlist sg;
+ struct virtqueue *vq = hvb->hinting_vq;
+ int err = 0;
+ struct hinting_data *hint_req;
+ u64 gpaddr;
+
+ hint_req = kmalloc(sizeof(*hint_req), GFP_KERNEL);
+ if (!hint_req)
+ return;
+ gpaddr = virt_to_phys(hvb->hinting_arr);
+ hint_req->phys_addr = cpu_to_virtio64(hvb->vdev, gpaddr);
+ hint_req->size = cpu_to_virtio32(hvb->vdev, entries);
+ sg_init_one(&sg, hint_req, sizeof(*hint_req));
+ err = virtqueue_add_outbuf(vq, &sg, 1, hint_req, GFP_KERNEL);
+ if (!err)
+ virtqueue_kick_sync(hvb->hinting_vq);
+
+ kfree(hint_req);
+}
+
+int page_hinting_prepare(void)
+{
+ hvb->hinting_arr = kmalloc_array(VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES,
+ sizeof(*hvb->hinting_arr), GFP_KERNEL);
+ if (!hvb->hinting_arr)
+ return -ENOMEM;
+ return 0;
+}
+
+void hint_pages(struct list_head *pages)
+{
+ struct page *page, *next;
+ unsigned long pfn;
+ int idx = 0, order;
+
+ list_for_each_entry_safe(page, next, pages, lru) {
+ pfn = page_to_pfn(page);
+ order = page_private(page);
+ hvb->hinting_arr[idx].phys_addr = pfn << PAGE_SHIFT;
+ hvb->hinting_arr[idx].size = (1 << order) * PAGE_SIZE;
+ idx++;
+ }
+ page_hinting_report(idx);
+}
+
+void page_hinting_cleanup(void)
+{
+ kfree(hvb->hinting_arr);
+}
+
+static const struct page_hinting_cb hcb = {
+ .prepare = page_hinting_prepare,
+ .hint_pages = hint_pages,
+ .cleanup = page_hinting_cleanup,
+ .max_pages = VIRTIO_BALLOON_PAGE_HINTING_MAX_PAGES,
+};
+#endif
+
static u32 page_to_balloon_pfn(struct page *page)
{
unsigned long pfn = page_to_pfn(page);
@@ -488,6 +574,7 @@ static int init_vqs(struct virtio_balloon *vb)
names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate";
names[VIRTIO_BALLOON_VQ_STATS] = NULL;
names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
+ names[VIRTIO_BALLOON_VQ_HINTING] = NULL;
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
names[VIRTIO_BALLOON_VQ_STATS] = "stats";
@@ -499,11 +586,18 @@ static int init_vqs(struct virtio_balloon *vb)
callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
}
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) {
+ names[VIRTIO_BALLOON_VQ_HINTING] = "hinting_vq";
+ callbacks[VIRTIO_BALLOON_VQ_HINTING] = NULL;
+ }
err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX,
vqs, callbacks, names, NULL, NULL);
if (err)
return err;
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING))
+ vb->hinting_vq = vqs[VIRTIO_BALLOON_VQ_HINTING];
+
vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE];
vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE];
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
@@ -942,6 +1036,14 @@ static int virtballoon_probe(struct virtio_device *vdev)
if (err)
goto out_del_balloon_wq;
}
+
+#ifdef CONFIG_PAGE_HINTING
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING) &&
+ page_hinting_flag) {
+ hvb = vb;
+ page_hinting_enable(&hcb);
+ }
+#endif
virtio_device_ready(vdev);
if (towards_target(vb))
@@ -989,6 +1091,12 @@ static void virtballoon_remove(struct virtio_device *vdev)
destroy_workqueue(vb->balloon_wq);
}
+#ifdef CONFIG_PAGE_HINTING
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) {
+ hvb = NULL;
+ page_hinting_disable();
+ }
+#endif
remove_common(vb);
#ifdef CONFIG_BALLOON_COMPACTION
if (vb->vb_dev_info.inode)
@@ -1043,8 +1151,10 @@ static unsigned int features[] = {
VIRTIO_BALLOON_F_MUST_TELL_HOST,
VIRTIO_BALLOON_F_STATS_VQ,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
+ VIRTIO_BALLOON_F_HINTING,
VIRTIO_BALLOON_F_FREE_PAGE_HINT,
VIRTIO_BALLOON_F_PAGE_POISON,
+ VIRTIO_BALLOON_F_HINTING,
};
static struct virtio_driver virtio_balloon_driver = {
diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index a1966cd7b677..25e4f817c660 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -29,6 +29,7 @@
#include <linux/virtio_types.h>
#include <linux/virtio_ids.h>
#include <linux/virtio_config.h>
+#include <linux/page_hinting.h>
/* The feature bitmap for virtio balloon */
#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
@@ -36,6 +37,7 @@
#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
#define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */
#define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */
+#define VIRTIO_BALLOON_F_HINTING 5 /* Page hinting virtqueue */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
@@ -108,4 +110,16 @@ struct virtio_balloon_stat {
__virtio64 val;
} __attribute__((packed));
+#ifdef CONFIG_PAGE_HINTING
+/*
+ * struct hinting_data- holds the information associated with hinting.
+ * @phys_add: physical address associated with a page or the array holding
+ * the array of isolated pages.
+ * @size: total size associated with the phys_addr.
+ */
+struct hinting_data {
+ __virtio64 phys_addr;
+ __virtio32 size;
+};
+#endif
#endif /* _LINUX_VIRTIO_BALLOON_H */
--
2.21.0
