diff options
Diffstat (limited to 'drivers/virtio/virtio_balloon.c')
| -rw-r--r-- | drivers/virtio/virtio_balloon.c | 51 |
1 files changed, 41 insertions, 10 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 9e95ca6..c2d05a8 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -28,6 +28,13 @@ #include <linux/slab.h> #include <linux/module.h> +/* + * Balloon device works in 4K page units. So each page is pointed to by + * multiple balloon pages. All memory counters in this driver are in balloon + * page units. + */ +#define VIRTIO_BALLOON_PAGES_PER_PAGE (PAGE_SIZE >> VIRTIO_BALLOON_PFN_SHIFT) + struct virtio_balloon { struct virtio_device *vdev; @@ -42,8 +49,13 @@ struct virtio_balloon /* Waiting for host to ack the pages we released. */ struct completion acked; - /* The pages we've told the Host we're not using. */ + /* Number of balloon pages we've told the Host we're not using. */ unsigned int num_pages; + /* + * The pages we've told the Host we're not using. + * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE + * to num_pages above. + */ struct list_head pages; /* The array of pfns we tell the Host about. */ @@ -66,7 +78,13 @@ static u32 page_to_balloon_pfn(struct page *page) BUILD_BUG_ON(PAGE_SHIFT < VIRTIO_BALLOON_PFN_SHIFT); /* Convert pfn from Linux page size to balloon page size. */ - return pfn >> (PAGE_SHIFT - VIRTIO_BALLOON_PFN_SHIFT); + return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE; +} + +static struct page *balloon_pfn_to_page(u32 pfn) +{ + BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE); + return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE); } static void balloon_ack(struct virtqueue *vq) @@ -96,12 +114,23 @@ static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq) wait_for_completion(&vb->acked); } +static void set_page_pfns(u32 pfns[], struct page *page) +{ + unsigned int i; + + /* Set balloon pfns pointing at this page. + * Note that the first pfn points at start of the page. */ + for (i = 0; i < VIRTIO_BALLOON_PAGES_PER_PAGE; i++) + pfns[i] = page_to_balloon_pfn(page) + i; +} + static void fill_balloon(struct virtio_balloon *vb, size_t num) { /* We can only do one array worth at a time. */ num = min(num, ARRAY_SIZE(vb->pfns)); - for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) { + for (vb->num_pfns = 0; vb->num_pfns < num; + vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); if (!page) { @@ -113,9 +142,9 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num) msleep(200); break; } - vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page); + set_page_pfns(vb->pfns + vb->num_pfns, page); + vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; totalram_pages--; - vb->num_pages++; list_add(&page->lru, &vb->pages); } @@ -130,8 +159,9 @@ static void release_pages_by_pfn(const u32 pfns[], unsigned int num) { unsigned int i; - for (i = 0; i < num; i++) { - __free_page(pfn_to_page(pfns[i])); + /* Find pfns pointing at start of each page, get pages and free them. */ + for (i = 0; i < num; i += VIRTIO_BALLOON_PAGES_PER_PAGE) { + __free_page(balloon_pfn_to_page(pfns[i])); totalram_pages++; } } @@ -143,11 +173,12 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num) /* We can only do one array worth at a time. */ num = min(num, ARRAY_SIZE(vb->pfns)); - for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) { + for (vb->num_pfns = 0; vb->num_pfns < num; + vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) { page = list_first_entry(&vb->pages, struct page, lru); list_del(&page->lru); - vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page); - vb->num_pages--; + set_page_pfns(vb->pfns + vb->num_pfns, page); + vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE; } /* |
