Re: [dpdk-dev] [PATCH 07/21] vhost: add iotlb helper functions

[Yuanhan Liu <yliu@fridaylinux.org>]

On Thu, Aug 31, 2017 at 11:50:09AM +0200, Maxime Coquelin wrote:
> diff --git a/lib/librte_vhost/iotlb.c b/lib/librte_vhost/iotlb.c
> new file mode 100644
> index 000000000..1b739dae5
> --- /dev/null
> +++ b/lib/librte_vhost/iotlb.c
> @@ -0,0 +1,231 @@
> +/*-
> + *   BSD LICENSE
> + *
> + *   Copyright (c) 2017 Red Hat, Inc.
> + *   Copyright (c) 2017 Maxime Coquelin <maxime.coquelin@redhat.com>

I'm not a lawer, but I have been told many years before, that you don't
have the copyright for the code you write for open source project, the
company you work for does.

Thus, it's more common to see something like following:
	Copyright , ... the commany ...
	Author:  Some One <...@...>

However, as you may have noticed, it's not common to put the authorship
in the source files. Though I don't object it.

[...]
> +#define IOTLB_CACHE_SIZE 1024
> +
> +static void vhost_user_iotlb_cache_remove_all(struct vhost_virtqueue *vq)
   ^^^^^^^^^^^^
Note that it's not the DPDK coding style to define a function.

> +{
> +	struct vhost_iotlb_entry *node, *temp_node;
> +
> +	rte_rwlock_write_lock(&vq->iotlb_lock);
> +
> +	TAILQ_FOREACH_SAFE(node, &vq->iotlb_list, next, temp_node) {
> +		TAILQ_REMOVE(&vq->iotlb_list, node, next);
> +		rte_mempool_put(vq->iotlb_pool, node);
> +	}
> +
> +	rte_rwlock_write_unlock(&vq->iotlb_lock);
> +}
> +
> +void vhost_user_iotlb_cache_insert(struct vhost_virtqueue *vq, uint64_t iova,
> +				uint64_t uaddr, uint64_t size, uint8_t perm)
> +{
> +	struct vhost_iotlb_entry *node, *new_node;
> +	int ret;
> +
> +	ret = rte_mempool_get(vq->iotlb_pool, (void **)&new_node);
> +	if (ret) {
> +		RTE_LOG(ERR, VHOST_CONFIG, "IOTLB pool empty, invalidate cache\n");

It's a cache, why not considering remove one to get space for new one?

> +		vhost_user_iotlb_cache_remove_all(vq);
> +		ret = rte_mempool_get(vq->iotlb_pool, (void **)&new_node);
> +		if (ret) {
> +			RTE_LOG(ERR, VHOST_CONFIG, "IOTLB pool still empty, failure\n");
> +			return;
> +		}
> +	}
> +
> +	new_node->iova = iova;
> +	new_node->uaddr = uaddr;
> +	new_node->size = size;
> +	new_node->perm = perm;
> +
> +	rte_rwlock_write_lock(&vq->iotlb_lock);
> +
> +	TAILQ_FOREACH(node, &vq->iotlb_list, next) {
> +		/*
> +		 * Entries must be invalidated before being updated.
> +		 * So if iova already in list, assume identical.
> +		 */
> +		if (node->iova == new_node->iova) {
> +			rte_mempool_put(vq->iotlb_pool, new_node);
> +			goto unlock;
> +		} else if (node->iova > new_node->iova) {
> +			TAILQ_INSERT_BEFORE(node, new_node, next);
> +			goto unlock;
> +		}
> +	}
> +
> +	TAILQ_INSERT_TAIL(&vq->iotlb_list, new_node, next);
> +
> +unlock:
> +	rte_rwlock_write_unlock(&vq->iotlb_lock);
> +}
> +
> +void vhost_user_iotlb_cache_remove(struct vhost_virtqueue *vq,
> +					uint64_t iova, uint64_t size)
> +{
> +	struct vhost_iotlb_entry *node, *temp_node;
> +
> +	if (unlikely(!size))
> +		return;
> +
> +	rte_rwlock_write_lock(&vq->iotlb_lock);
> +
> +	TAILQ_FOREACH_SAFE(node, &vq->iotlb_list, next, temp_node) {
> +		/* Sorted list */

I'd like to put such comments at the struct declartion, so that you don't
have to mention it many times that it's a sorted list.

> +		if (unlikely(node->iova >= iova + size)) {
> +			break;
> +		} else if ((node->iova < iova + size) &&
> +					(iova < node->iova + node->size)) {
> +			TAILQ_REMOVE(&vq->iotlb_list, node, next);
> +			rte_mempool_put(vq->iotlb_pool, node);
> +			continue;
> +		}
> +	}
> +
> +	rte_rwlock_write_unlock(&vq->iotlb_lock);
> +}
> +
[...]
> +int vhost_user_iotlb_init(struct virtio_net *dev, int vq_index)
> +{
> +	char pool_name[RTE_MEMPOOL_NAMESIZE];
> +	struct vhost_virtqueue *vq = dev->virtqueue[vq_index];
> +	int ret = -1, socket;
> +
> +	if (vq->iotlb_pool) {
> +		/*
> +		 * The cache has already been initialized,
> +		 * just drop all entries
> +		 */
> +		vhost_user_iotlb_cache_remove_all(vq);
> +		return 0;
> +	}
> +
> +#ifdef RTE_LIBRTE_VHOST_NUMA
> +	ret = get_mempolicy(&socket, NULL, 0, vq, MPOL_F_NODE | MPOL_F_ADDR);
> +#endif
> +	if (ret)
> +		socket = 0;
> +
> +	rte_rwlock_init(&vq->iotlb_lock);
> +
> +	TAILQ_INIT(&vq->iotlb_list);
> +
> +	snprintf(pool_name, sizeof(pool_name), "iotlb_cache_%d_%d",
> +			dev->vid, vq_index);

iotlb_cache is too generic. Adding a "vhost" prefix?

	--yliu