virtio: Force use of power-of-two for descriptor ring sizes

[linux-2.6-omap-h63xx.git] / Documentation / lguest / lguest.c

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 157f6a26b93947baccbca0f9802dddd29a2ee970..42008395534d67c39dfc1da086ee9f35eaa95c3a 100644 (file)
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -62,8 +62,8 @@ typedef uint8_t u8;
 #endif
 /* We can have up to 256 pages for devices. */
 #define DEVICE_PAGES 256
-/* This fits nicely in a single 4096-byte page. */
-#define VIRTQUEUE_NUM 127
+/* This will occupy 2 pages: it must be a power of 2. */
+#define VIRTQUEUE_NUM 128
 
 /*L:120 verbose is both a global flag and a macro.  The C preprocessor allows
  * this, and although I wouldn't recommend it, it works quite nicely here. */
@@ -1036,7 +1036,8 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs,
        void *p;
 
        /* First we need some pages for this virtqueue. */
-       pages = (vring_size(num_descs) + getpagesize() - 1) / getpagesize();
+       pages = (vring_size(num_descs, getpagesize()) + getpagesize() - 1)
+               / getpagesize();
        p = get_pages(pages);
 
        /* Initialize the configuration. */
@@ -1045,7 +1046,7 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs,
        vq->config.pfn = to_guest_phys(p) / getpagesize();
 
        /* Initialize the vring. */
-       vring_init(&vq->vring, num_descs, p);
+       vring_init(&vq->vring, num_descs, p, getpagesize());
 
        /* Add the configuration information to this device's descriptor. */
        add_desc_field(dev, VIRTIO_CONFIG_F_VIRTQUEUE,