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 <[email protected]> --- 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
