[RFCv2 09/12] virtio-ring: Add BUG_ON checking on host/guest ring type

[Sjur Brændeland <sjur@xxxxxxxxxxxxxx>]

From: Sjur Brændeland <sjur.brandeland@xxxxxxxxxxxxxx>

Add BUG_ON to ensure that the correct virtio queue type is
used for the virtqueue functions.
In addition the function virtqueue_kick_prepare() is changed so
that it always returns true if the virtio-ring is reversed.

Signed-off-by: Sjur Brændeland <sjur.brandeland@xxxxxxxxxxxxxx>
---
 drivers/virtio/virtio_ring.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 67f7bcd..a6f38c1 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -176,6 +176,7 @@ int virtqueue_add_buf(struct virtqueue *_vq,
 
 	START_USE(vq);
 
+	BUG_ON(vq->vq.reversed);
 	BUG_ON(data == NULL);
 
 #ifdef DEBUG
@@ -282,6 +283,9 @@ bool virtqueue_kick_prepare(struct virtqueue *_vq)
 	u16 new, old;
 	bool needs_kick;
 
+	if (_vq->reversed)
+		return true;
+
 	START_USE(vq);
 	/* We need to expose available array entries before checking avail
 	 * event. */
@@ -346,6 +350,7 @@ static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
 {
 	unsigned int i;
 
+	BUG_ON(vq->vq.reversed);
 	/* Clear data ptr. */
 	vq->data[head] = NULL;
 
@@ -395,6 +400,7 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
 	unsigned int i;
 	u16 last_used;
 
+	BUG_ON(vq->vq.reversed);
 	START_USE(vq);
 
 	if (unlikely(vq->broken)) {
@@ -457,6 +463,7 @@ EXPORT_SYMBOL_GPL(virtqueue_get_buf);
 void virtqueue_disable_cb(struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
+	BUG_ON(vq->vq.reversed);
 
 	vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
 }
@@ -477,6 +484,7 @@ bool virtqueue_enable_cb(struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
+	BUG_ON(vq->vq.reversed);
 	START_USE(vq);
 
 	/* We optimistically turn back on interrupts, then check if there was
@@ -515,6 +523,7 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *_vq)
 	struct vring_virtqueue *vq = to_vvq(_vq);
 	u16 bufs;
 
+	BUG_ON(vq->vq.reversed);
 	START_USE(vq);
 
 	/* We optimistically turn back on interrupts, then check if there was
@@ -551,6 +560,7 @@ void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
 	unsigned int i;
 	void *buf;
 
+	BUG_ON(vq->vq.reversed);
 	START_USE(vq);
 
 	for (i = 0; i < vq->vring.num; i++) {
@@ -575,6 +585,7 @@ irqreturn_t __vring_interrupt(int irq, void *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
+	BUG_ON(vq->vq.reversed);
 	if (!more_used(vq)) {
 		pr_debug("virtqueue interrupt with no work for %p\n", vq);
 		return IRQ_NONE;
-- 
1.7.5.4

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