virtio: Don't use PAGE_SIZE in virtio_pci.c

The virtio PCI devices don't depend on the guest page size.  This matters
now PowerPC virtio is gaining ground (they like 64k pages).

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

2 files changed, 5 insertions, 1 deletions

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index e37d686edfe0..c2cd69ba0a8c 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -245,7 +245,7 @@ static struct virtqueue *vp_find_vq(struct virtio_device *vdev, unsigned index,
         }
 
         /* activate the queue */
-        iowrite32(virt_to_phys(info->queue) >> PAGE_SHIFT,
+        iowrite32(virt_to_phys(info->queue) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT,
                   vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
 
         /* create the vring */
diff --git a/include/linux/virtio_pci.h b/include/linux/virtio_pci.h
index cdef35742932..e13d7ebcf576 100644
--- a/include/linux/virtio_pci.h
+++ b/include/linux/virtio_pci.h
@@ -53,4 +53,8 @@
 
 /* Virtio ABI version, this must match exactly */
 #define VIRTIO_PCI_ABI_VERSION          0
+
+/* 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
 #endif