diff options
| author | Hollis Blanchard <hollisb@us.ibm.com> | 2008-11-13 15:48:33 -0600 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2008-12-30 09:26:04 +1030 |
| commit | 1b4aa2faeca1b9922033daf2475b6fc13b0ffea6 (patch) | |
| tree | b94e3f4ec45151e51ad1b3dfecabc5391684c725 | |
| parent | 87c7d57c17ade5024d95b6ca0da249da49b0672a (diff) | |
virtio: avoid implicit use of Linux page size in balloon interface
Make the balloon interface always use 4K pages, and convert Linux pfns if
necessary. This patch assumes that Linux's PAGE_SHIFT will never be less than
12.
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (modified)
| -rw-r--r-- | drivers/virtio/virtio_balloon.c | 13 | ||||
| -rw-r--r-- | include/linux/virtio_balloon.h | 3 |
2 files changed, 14 insertions, 2 deletions
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 62eab43152d..59268266b79 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -56,6 +56,15 @@ static struct virtio_device_id id_table[] = { { 0 }, }; +static u32 page_to_balloon_pfn(struct page *page) +{ + unsigned long pfn = page_to_pfn(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); +} + static void balloon_ack(struct virtqueue *vq) { struct virtio_balloon *vb; @@ -99,7 +108,7 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num) msleep(200); break; } - vb->pfns[vb->num_pfns] = page_to_pfn(page); + vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page); totalram_pages--; vb->num_pages++; list_add(&page->lru, &vb->pages); @@ -132,7 +141,7 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num) for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) { page = list_first_entry(&vb->pages, struct page, lru); list_del(&page->lru); - vb->pfns[vb->num_pfns] = page_to_pfn(page); + vb->pfns[vb->num_pfns] = page_to_balloon_pfn(page); vb->num_pages--; } diff --git a/include/linux/virtio_balloon.h b/include/linux/virtio_balloon.h index c30c7bfbf39..8726ff77763 100644 --- a/include/linux/virtio_balloon.h +++ b/include/linux/virtio_balloon.h @@ -10,6 +10,9 @@ /* The feature bitmap for virtio balloon */ #define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */ +/* Size of a PFN in the balloon interface. */ +#define VIRTIO_BALLOON_PFN_SHIFT 12 + struct virtio_balloon_config { /* Number of pages host wants Guest to give up. */ |