Re: [PATCH 1/5] virtio-ring: move queue_index to vring_virtqueue

[Jason Wang <jasowang@redhat.com>]

On 08/28/2012 07:54 PM, Paolo Bonzini wrote:
> From: Jason Wang<jasowang@redhat.com>
>
> 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>
> ---
> 	I fixed the problems in Jason's v5 (posted at
> 	http://permalink.gmane.org/gmane.linux.kernel.virtualization/15910)
> 	and switched from virtio_set_queue_index to a new argument of
> 	vring_new_virtqueue.  This breaks at compile-time any virtio
> 	transport that is not updated.

Thanks Paolo. I'm fine with this patch.
>
>   drivers/lguest/lguest_device.c         |    2 +-
>   drivers/remoteproc/remoteproc_virtio.c |    2 +-
>   drivers/s390/kvm/kvm_virtio.c          |    2 +-
>   drivers/virtio/virtio_mmio.c           |   12 ++++--------
>   drivers/virtio/virtio_pci.c            |   13 +++++--------
>   drivers/virtio/virtio_ring.c           |   14 +++++++++++++-
>   include/linux/virtio.h                 |    2 ++
>   include/linux/virtio_ring.h            |    3 ++-
>   8 files changed, 29 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
> index 9e8388e..ccb7dfb 100644
> --- a/drivers/lguest/lguest_device.c
> +++ b/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;
> diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
> index 3541b44..343c194 100644
> --- a/drivers/remoteproc/remoteproc_virtio.c
> +++ b/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);
> diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
> index 47cccd5..5565af2 100644
> --- a/drivers/s390/kvm/kvm_virtio.c
> +++ b/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) {
> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> index 453db0c..008bf58 100644
> --- a/drivers/virtio/virtio_mmio.c
> +++ b/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;
> diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
> index 2e03d41..d902464 100644
> --- a/drivers/virtio/virtio_pci.c
> +++ b/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,
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 5aa43c3..e639584 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/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;
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index a1ba8bb..533b115 100644
> --- a/include/linux/virtio.h
> +++ b/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
> diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
> index e338730..c2d793a 100644
> --- a/include/linux/virtio_ring.h
> +++ b/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,