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/Kconfig | 1 + drivers/virtio/virtio_balloon.c | 91 ++++++++++++++++++++++++++++- include/uapi/linux/virtio_balloon.h | 11 ++++ 3 files changed, 102 insertions(+), 1 deletion(-) diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig index 023fc3bc01c6..dcc0cb4269a5 100644 --- a/drivers/virtio/Kconfig +++ b/drivers/virtio/Kconfig @@ -47,6 +47,7 @@ config VIRTIO_BALLOON tristate "Virtio balloon driver" depends on VIRTIO select MEMORY_BALLOON + select PAGE_HINTING ---help--- This driver supports increasing and decreasing the amount of memory within a KVM guest. diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 44339fc87cc7..1fb0eb0b2c20 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -18,6 +18,7 @@ #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 @@ -35,6 +36,12 @@ /* The size of a free page block in bytes */ #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) +/* Number of isolated pages to be reported to the host at a time. + * TODO: + * 1. Set it via host. + * 2. Find an optimal value for this. + */ +#define PAGE_HINTING_MAX_PAGES 16 #ifdef CONFIG_BALLOON_COMPACTION static struct vfsmount *balloon_mnt; @@ -45,6 +52,7 @@ 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 }; @@ -54,7 +62,8 @@ 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; @@ -112,6 +121,9 @@ struct virtio_balloon { /* To register a shrinker to shrink memory upon memory pressure */ struct shrinker shrinker; + + /* Array object pointing at the isolated pages ready for hinting */ + struct isolated_memory isolated_pages[PAGE_HINTING_MAX_PAGES]; }; static struct virtio_device_id id_table[] = { @@ -119,6 +131,66 @@ static struct virtio_device_id id_table[] = { { 0 }, }; +static struct page_hinting_config page_hinting_conf; +bool page_hinting_flag = true; +struct virtio_balloon *hvb; +module_param(page_hinting_flag, bool, 0444); +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); + +static int page_hinting_report(void) +{ + struct virtqueue *vq = hvb->hinting_vq; + struct scatterlist sg; + int err = 0, unused; + + mutex_lock(&hvb->balloon_lock); + sg_init_one(&sg, hvb->isolated_pages, sizeof(hvb->isolated_pages[0]) * + PAGE_HINTING_MAX_PAGES); + err = virtqueue_add_outbuf(vq, &sg, 1, hvb, GFP_KERNEL); + if (!err) + virtqueue_kick(hvb->hinting_vq); + wait_event(hvb->acked, virtqueue_get_buf(vq, &unused)); + mutex_unlock(&hvb->balloon_lock); + return err; +} + +void hint_pages(struct list_head *pages) +{ + struct device *dev = &hvb->vdev->dev; + struct page *page, *next; + int idx = 0, order, err; + unsigned long pfn; + + list_for_each_entry_safe(page, next, pages, lru) { + pfn = page_to_pfn(page); + order = page_private(page); + hvb->isolated_pages[idx].phys_addr = pfn << PAGE_SHIFT; + hvb->isolated_pages[idx].size = (1 << order) * PAGE_SIZE; + idx++; + } + err = page_hinting_report(); + if (err < 0) + dev_err(dev, "Failed to hint pages, err = %d\n", err); +} + +static void page_hinting_init(struct virtio_balloon *vb) +{ + struct device *dev = &vb->vdev->dev; + int err; + + page_hinting_conf.hint_pages = hint_pages; + page_hinting_conf.max_pages = PAGE_HINTING_MAX_PAGES; + err = page_hinting_enable(&page_hinting_conf); + if (err < 0) { + dev_err(dev, "Failed to enable page-hinting, err = %d\n", err); + page_hinting_flag = false; + page_hinting_conf.hint_pages = NULL; + page_hinting_conf.max_pages = 0; + return; + } + hvb = vb; +} + static u32 page_to_balloon_pfn(struct page *page) { unsigned long pfn = page_to_pfn(page); @@ -475,6 +547,7 @@ 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"; @@ -486,11 +559,18 @@ 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] = balloon_ack; + } 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)) { @@ -929,6 +1009,9 @@ static int virtballoon_probe(struct virtio_device *vdev) if (err) goto out_del_balloon_wq; } + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING) && + page_hinting_flag) + page_hinting_init(vb); virtio_device_ready(vdev); if (towards_target(vb)) @@ -976,6 +1059,10 @@ static void virtballoon_remove(struct virtio_device *vdev) destroy_workqueue(vb->balloon_wq); } + if (!page_hinting_flag) { + hvb = NULL; + page_hinting_disable(); + } remove_common(vb); #ifdef CONFIG_BALLOON_COMPACTION if (vb->vb_dev_info.inode) @@ -1030,8 +1117,10 @@ 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..29eed0ec83d3 100644 --- a/include/uapi/linux/virtio_balloon.h +++ b/include/uapi/linux/virtio_balloon.h @@ -36,6 +36,8 @@ #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 */ +/* TODO: Find a better name to avoid any confusion with FREE_PAGE_HINT */ +#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 +110,13 @@ struct virtio_balloon_stat { __virtio64 val; } __attribute__((packed)); +/* + * struct isolated_memory- holds the pages which will be reported to the host. + * @phys_add: physical address associated with a page. + * @size: total size of memory to be reported. + */ +struct isolated_memory { + __virtio64 phys_addr; + __virtio64 size; +}; #endif /* _LINUX_VIRTIO_BALLOON_H */ -- 2.21.0
