virtio: Don't use PAGE_SIZE for vring alignment in virtio_pci.

That doesn't work for non-4k guests which are now appearing.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 6 insertions, 2 deletions

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index c2cd69ba0a8c..f28643f3a4e8 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -237,7 +237,7 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
         info->queue_index = index;
         info->num = num;
 
-        size = PAGE_ALIGN(vring_size(num, PAGE_SIZE));
+        size = PAGE_ALIGN(vring_size(num, VIRTIO_PCI_VRING_ALIGN));
         info->queue = alloc_pages_exact(size, GFP_KERNEL|__GFP_ZERO);
         if (info->queue == NULL) {
                 err = -ENOMEM;
@@ -290,7 +290,7 @@ static void vp_del_vq(struct virtqueue *vq)
         iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
         iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
 
-        size = PAGE_ALIGN(vring_size(info->num, PAGE_SIZE));
+        size = PAGE_ALIGN(vring_size(info->num, VIRTIO_PCI_VRING_ALIGN));
         free_pages_exact(info->queue, size);
         kfree(info);
 }
diff --git a/include/linux/virtio_pci.h b/include/linux/virtio_pci.h
index e13d7ebcf576..cd0fd5d181a6 100644
--- a/include/linux/virtio_pci.h
+++ b/include/linux/virtio_pci.h
@@ -57,4 +57,8 @@
 /* How many bits to shift physical queue address written to QUEUE_PFN.
  * 12 is historical, and due to x86 page size. */
 #define VIRTIO_PCI_QUEUE_ADDR_SHIFT     12
+
+/* The alignment to use between consumer and producer parts of vring.
+ * x86 pagesize again. */
+#define VIRTIO_PCI_VRING_ALIGN          4096
 #endif