From 498af14783935af487d17dbee4ac451783cbc2b7 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 30 Dec 2008 09:25:57 -0600
Subject: 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>

diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index c2cd69b..f28643f 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 e13d7eb..cd0fd5d 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
-- 
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