From 1b4aa2faeca1b9922033daf2475b6fc13b0ffea6 Mon Sep 17 00:00:00 2001 From: Hollis Blanchard Date: Thu, 13 Nov 2008 15:48:33 -0600 Subject: 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 Signed-off-by: Rusty Russell (modified) --- drivers/virtio/virtio_balloon.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) (limited to 'drivers/virtio/virtio_balloon.c') 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--; } -- cgit v1.2.3