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authorHollis Blanchard <hollisb@us.ibm.com>2008-11-13 15:48:33 -0600
committerRusty Russell <rusty@rustcorp.com.au>2008-12-30 09:26:04 +1030
commit1b4aa2faeca1b9922033daf2475b6fc13b0ffea6 (patch)
treeb94e3f4ec45151e51ad1b3dfecabc5391684c725 /drivers/virtio/virtio_balloon.c
parent87c7d57c17ade5024d95b6ca0da249da49b0672a (diff)
downloadvexpress-lsk-1b4aa2faeca1b9922033daf2475b6fc13b0ffea6.tar.gz
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)
Diffstat (limited to 'drivers/virtio/virtio_balloon.c')
-rw-r--r--drivers/virtio/virtio_balloon.c13
1 files changed, 11 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--;
}