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>

1 files changed, 4 insertions, 0 deletions

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