virtio-ring: move queue_index to vring_virtqueue

Instead of storing the queue index in transport-specific virtio structs,
this patch moves them to vring_virtqueue and introduces an helper to get
the value.  This lets drivers simplify their management and tracing of
virtqueues.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/lguest/lguest_device.c

@@ -296,7 +296,7 @@ static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
 	 * to 'true': the host just a(nother) SMP CPU, so we only need inter-cpu
 	 * barriers.
 	 */
-	vq = vring_new_virtqueue(lvq->config.num, LGUEST_VRING_ALIGN, vdev,
+	vq = vring_new_virtqueue(index, lvq->config.num, LGUEST_VRING_ALIGN, vdev,
 				 true, lvq->pages, lg_notify, callback, name);
 	if (!vq) {
 		err = -ENOMEM;

drivers/remoteproc/remoteproc_virtio.c

@@ -103,7 +103,7 @@ static struct virtqueue *rp_find_vq(struct virtio_device *vdev,
 	 * Create the new vq, and tell virtio we're not interested in
 	 * the 'weak' smp barriers, since we're talking with a real device.
 	 */
-	vq = vring_new_virtqueue(len, rvring->align, vdev, false, addr,
+	vq = vring_new_virtqueue(id, len, rvring->align, vdev, false, addr,
 					rproc_virtio_notify, callback, name);
 	if (!vq) {
 		dev_err(dev, "vring_new_virtqueue %s failed\n", name);

drivers/s390/kvm/kvm_virtio.c

@@ -198,7 +198,7 @@ static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
 	if (err)
 		goto out;
 
-	vq = vring_new_virtqueue(config->num, KVM_S390_VIRTIO_RING_ALIGN,
+	vq = vring_new_virtqueue(index, config->num, KVM_S390_VIRTIO_RING_ALIGN,
 				 vdev, true, (void *) config->address,
 				 kvm_notify, callback, name);
 	if (!vq) {

drivers/virtio/virtio_mmio.c

@@ -131,9 +131,6 @@ struct virtio_mmio_vq_info {
 	/* the number of entries in the queue */
 	unsigned int num;
 
-	/* the index of the queue */
-	int queue_index;
-
 	/* the virtual address of the ring queue */
 	void *queue;
 
@@ -225,11 +222,10 @@ static void vm_reset(struct virtio_device *vdev)
 static void vm_notify(struct virtqueue *vq)
 {
 	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
-	struct virtio_mmio_vq_info *info = vq->priv;
 
 	/* We write the queue's selector into the notification register to
 	 * signal the other end */
-	writel(info->queue_index, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
+	writel(virtqueue_get_queue_index(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
 }
 
 /* Notify all virtqueues on an interrupt. */
@@ -270,6 +266,7 @@ static void vm_del_vq(struct virtqueue *vq)
 	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
 	struct virtio_mmio_vq_info *info = vq->priv;
 	unsigned long flags, size;
+	unsigned int index = virtqueue_get_queue_index(vq);
 
 	spin_lock_irqsave(&vm_dev->lock, flags);
 	list_del(&info->node);
@@ -278,7 +275,7 @@ static void vm_del_vq(struct virtqueue *vq)
 	vring_del_virtqueue(vq);
 
 	/* Select and deactivate the queue */
-	writel(info->queue_index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
+	writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
 	writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
 
 	size = PAGE_ALIGN(vring_size(info->num, VIRTIO_MMIO_VRING_ALIGN));
@@ -324,7 +321,6 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
 		err = -ENOMEM;
 		goto error_kmalloc;
 	}
-	info->queue_index = index;
 
 	/* Allocate pages for the queue - start with a queue as big as
 	 * possible (limited by maximum size allowed by device), drop down
@@ -356,7 +352,7 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
 			vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
 
 	/* Create the vring */
-	vq = vring_new_virtqueue(info->num, VIRTIO_MMIO_VRING_ALIGN, vdev,
+	vq = vring_new_virtqueue(index, info->num, VIRTIO_MMIO_VRING_ALIGN, vdev,
 				 true, info->queue, vm_notify, callback, name);
 	if (!vq) {
 		err = -ENOMEM;

drivers/virtio/virtio_pci.c

@@ -79,9 +79,6 @@ struct virtio_pci_vq_info
 	/* the number of entries in the queue */
 	int num;
 
-	/* the index of the queue */
-	int queue_index;
-
 	/* the virtual address of the ring queue */
 	void *queue;
 
@@ -202,11 +199,11 @@ static void vp_reset(struct virtio_device *vdev)
 static void vp_notify(struct virtqueue *vq)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
-	struct virtio_pci_vq_info *info = vq->priv;
 
 	/* we write the queue's selector into the notification register to
 	 * signal the other end */
-	iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY);
+	iowrite16(virtqueue_get_queue_index(vq),
+		  vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY);
 }
 
 /* Handle a configuration change: Tell driver if it wants to know. */
@@ -402,7 +399,6 @@ static struct virtqueue *setup_vq(struct virtio_device *vdev, unsigned index,
 	if (!info)
 		return ERR_PTR(-ENOMEM);
 
-	info->queue_index = index;
 	info->num = num;
 	info->msix_vector = msix_vec;
 
@@ -418,7 +414,7 @@ static struct virtqueue *setup_vq(struct virtio_device *vdev, unsigned index,
 		  vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
 
 	/* create the vring */
-	vq = vring_new_virtqueue(info->num, VIRTIO_PCI_VRING_ALIGN, vdev,
+	vq = vring_new_virtqueue(index, info->num, VIRTIO_PCI_VRING_ALIGN, vdev,
 				 true, info->queue, vp_notify, callback, name);
 	if (!vq) {
 		err = -ENOMEM;
@@ -467,7 +463,8 @@ static void vp_del_vq(struct virtqueue *vq)
 	list_del(&info->node);
 	spin_unlock_irqrestore(&vp_dev->lock, flags);
 
-	iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+	iowrite16(virtqueue_get_queue_index(vq),
+		vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
 
 	if (vp_dev->msix_enabled) {
 		iowrite16(VIRTIO_MSI_NO_VECTOR,

drivers/virtio/virtio_ring.c

@@ -106,6 +106,9 @@ struct vring_virtqueue
 	/* How to notify other side. FIXME: commonalize hcalls! */
 	void (*notify)(struct virtqueue *vq);
 
+	/* Index of the queue */
+	int queue_index;
+
 #ifdef DEBUG
 	/* They're supposed to lock for us. */
 	unsigned int in_use;
@@ -171,6 +174,13 @@ static int vring_add_indirect(struct vring_virtqueue *vq,
 	return head;
 }
 
+int virtqueue_get_queue_index(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	return vq->queue_index;
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_queue_index);
+
 /**
  * virtqueue_add_buf - expose buffer to other end
  * @vq: the struct virtqueue we're talking about.
@@ -616,7 +626,8 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
 }
 EXPORT_SYMBOL_GPL(vring_interrupt);
 
-struct virtqueue *vring_new_virtqueue(unsigned int num,
+struct virtqueue *vring_new_virtqueue(unsigned int index,
+				      unsigned int num,
 				      unsigned int vring_align,
 				      struct virtio_device *vdev,
 				      bool weak_barriers,
@@ -647,6 +658,7 @@ struct virtqueue *vring_new_virtqueue(unsigned int num,
 	vq->broken = false;
 	vq->last_used_idx = 0;
 	vq->num_added = 0;
+	vq->queue_index = index;
 	list_add_tail(&vq->vq.list, &vdev->vqs);
 #ifdef DEBUG
 	vq->in_use = false;

include/linux/virtio.h

@@ -50,6 +50,8 @@ void *virtqueue_detach_unused_buf(struct virtqueue *vq);
 
 unsigned int virtqueue_get_vring_size(struct virtqueue *vq);
 
+int virtqueue_get_queue_index(struct virtqueue *vq);
+
 /**
  * virtio_device - representation of a device using virtio
  * @index: unique position on the virtio bus

include/linux/virtio_ring.h

@@ -165,7 +165,8 @@ static inline int vring_need_event(__u16 event_idx, __u16 new_idx, __u16 old)
 struct virtio_device;
 struct virtqueue;
 
-struct virtqueue *vring_new_virtqueue(unsigned int num,
+struct virtqueue *vring_new_virtqueue(unsigned int index,
+				      unsigned int num,
 				      unsigned int vring_align,
 				      struct virtio_device *vdev,
 				      bool weak_barriers,