[dpdk-dev] [PATCH 12/14] vhost: dequeue for packed queues
Maxime Coquelin
maxime.coquelin at redhat.com
Thu Feb 1 10:35:18 CET 2018
On 01/29/2018 03:11 PM, Jens Freimann wrote:
> Implement code to dequeue and process descriptors from
> the vring if VIRTIO_F_PACKED is enabled.
>
> Check if descriptor was made available by driver by looking at
> VIRTIO_F_DESC_AVAIL flag in descriptor. If so dequeue and set
> the used flag VIRTIO_F_DESC_USED to the current value of the
> used wrap counter.
>
> Used ring wrap counter needs to be toggled when last descriptor is
> written out. This allows the host/guest to detect new descriptors even
> after the ring has wrapped.
>
> Signed-off-by: Jens Freimann <jfreimann at redhat.com>
> ---
> lib/librte_vhost/vhost.c | 1 +
> lib/librte_vhost/vhost.h | 1 +
> lib/librte_vhost/virtio_net.c | 194 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 196 insertions(+)
>
> diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
> index 78913912c..e5f58d9c8 100644
> --- a/lib/librte_vhost/vhost.c
> +++ b/lib/librte_vhost/vhost.c
> @@ -191,6 +191,7 @@ init_vring_queue(struct virtio_net *dev, uint32_t vring_idx)
>
> vq->kickfd = VIRTIO_UNINITIALIZED_EVENTFD;
> vq->callfd = VIRTIO_UNINITIALIZED_EVENTFD;
> + vq->used_wrap_counter = 1;
>
> vhost_user_iotlb_init(dev, vring_idx);
> /* Backends are set to -1 indicating an inactive device. */
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 8554d51d8..a3d4214b6 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -106,6 +106,7 @@ struct vhost_virtqueue {
>
> struct batch_copy_elem *batch_copy_elems;
> uint16_t batch_copy_nb_elems;
> + uint32_t used_wrap_counter;
>
> rte_rwlock_t iotlb_lock;
> rte_rwlock_t iotlb_pending_lock;
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index edfab3ba6..5d4cfe8cc 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -19,6 +19,7 @@
>
> #include "iotlb.h"
> #include "vhost.h"
> +#include "virtio-1.1.h"
>
> #define MAX_PKT_BURST 32
>
> @@ -1111,6 +1112,199 @@ restore_mbuf(struct rte_mbuf *m)
> }
> }
>
> +static inline uint16_t
> +dequeue_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
> + struct rte_mempool *mbuf_pool, struct rte_mbuf *m,
> + struct vring_desc_1_1 *descs)
> +{
> + struct vring_desc_1_1 *desc;
> + uint64_t desc_addr;
> + uint32_t desc_avail, desc_offset;
> + uint32_t mbuf_avail, mbuf_offset;
> + uint32_t cpy_len;
> + struct rte_mbuf *cur = m, *prev = m;
> + struct virtio_net_hdr *hdr = NULL;
> + uint16_t head_idx = vq->last_used_idx & (vq->size - 1);
> + int wrap_counter = vq->used_wrap_counter;
> +
> + desc = &descs[vq->last_used_idx & (vq->size - 1)];
> + if (unlikely((desc->len < dev->vhost_hlen)) ||
> + (desc->flags & VRING_DESC_F_INDIRECT))
> + rte_panic("INDIRECT not supported yet");
Using rte_panic() may not be a good idea here, because a malicious guest
could make the vswitch to crash easily.
> +
> + desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
You should use vhost_iova_to_vva() here and everywhere else, otherwise
you break IOMMU support.
> + if (unlikely(!desc_addr))
> + return -1;
> +
> + if (virtio_net_with_host_offload(dev)) {
> + hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
> + rte_prefetch0(hdr);
> + }
> +
> + /*
> + * A virtio driver normally uses at least 2 desc buffers
> + * for Tx: the first for storing the header, and others
> + * for storing the data.
> + */
> + if (likely((desc->len == dev->vhost_hlen) &&
> + (desc->flags & VRING_DESC_F_NEXT) != 0)) {
> + if ((++vq->last_used_idx & (vq->size - 1)) == 0)
> + toggle_wrap_counter(vq);
> +
> + desc = &descs[vq->last_used_idx & (vq->size - 1)];
> +
> + if (unlikely(desc->flags & VRING_DESC_F_INDIRECT))
> + rte_panic("INDIRECT not supported yet");
Ditto.
> +
> + desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
> + if (unlikely(!desc_addr))
> + return -1;
> +
> + desc_offset = 0;
> + desc_avail = desc->len;
> + } else {
> + desc_avail = desc->len - dev->vhost_hlen;
> + desc_offset = dev->vhost_hlen;
> + }
> +
> + rte_prefetch0((void *)(uintptr_t)(desc_addr + desc_offset));
> +
> + PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset), desc_avail, 0);
> +
> + mbuf_offset = 0;
> + mbuf_avail = m->buf_len - RTE_PKTMBUF_HEADROOM;
> + while (1) {
> + uint64_t hpa;
> +
> + cpy_len = RTE_MIN(desc_avail, mbuf_avail);
> +
> + /*
> + * A desc buf might across two host physical pages that are
> + * not continuous. In such case (gpa_to_hpa returns 0), data
> + * will be copied even though zero copy is enabled.
> + */
> + if (unlikely(dev->dequeue_zero_copy && (hpa = gpa_to_hpa(dev,
> + desc->addr + desc_offset, cpy_len)))) {
> + cur->data_len = cpy_len;
> + cur->data_off = 0;
> + cur->buf_addr = (void *)(uintptr_t)desc_addr;
> + cur->buf_physaddr = hpa;
> +
> + /*
> + * In zero copy mode, one mbuf can only reference data
> + * for one or partial of one desc buff.
> + */
> + mbuf_avail = cpy_len;
> + } else {
> + rte_memcpy(rte_pktmbuf_mtod_offset(cur, void *,
> + mbuf_offset),
> + (void *)((uintptr_t)(desc_addr + desc_offset)),
> + cpy_len);
> + }
> +
> + mbuf_avail -= cpy_len;
> + mbuf_offset += cpy_len;
> + desc_avail -= cpy_len;
> + desc_offset += cpy_len;
> +
> + /* This desc reaches to its end, get the next one */
> + if (desc_avail == 0) {
> + if ((desc->flags & VRING_DESC_F_NEXT) == 0)
> + break;
> +
> + if ((++vq->last_used_idx & (vq->size - 1)) == 0)
> + toggle_wrap_counter(vq);
> +
> + desc = &descs[vq->last_used_idx & (vq->size - 1)];
> + if (unlikely(desc->flags & VRING_DESC_F_INDIRECT))
> + rte_panic("INDIRECT not supported yet");
> +
> + desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
> + if (unlikely(!desc_addr))
> + return -1;
> +
> + rte_prefetch0((void *)(uintptr_t)desc_addr);
> +
> + desc_offset = 0;
> + desc_avail = desc->len;
> +
> + PRINT_PACKET(dev, (uintptr_t)desc_addr, desc->len, 0);
> + }
> +
> + /*
> + * This mbuf reaches to its end, get a new one
> + * to hold more data.
> + */
> + if (mbuf_avail == 0) {
> + cur = rte_pktmbuf_alloc(mbuf_pool);
> + if (unlikely(cur == NULL)) {
> + RTE_LOG(ERR, VHOST_DATA, "Failed to "
> + "allocate memory for mbuf.\n");
> + return -1;
> + }
> +
> + prev->next = cur;
> + prev->data_len = mbuf_offset;
> + m->nb_segs += 1;
> + m->pkt_len += mbuf_offset;
> + prev = cur;
> +
> + mbuf_offset = 0;
> + mbuf_avail = cur->buf_len - RTE_PKTMBUF_HEADROOM;
> + }
> + }
> +
> + if (hdr)
> + vhost_dequeue_offload(hdr, m);
> +
> + if ((++vq->last_used_idx & (vq->size - 1)) == 0)
> + toggle_wrap_counter(vq);
> +
> + rte_smp_wmb();
> + _set_desc_used(&descs[head_idx], wrap_counter);
> +
> + prev->data_len = mbuf_offset;
> + m->pkt_len += mbuf_offset;
> +
> + return 0;
> +}
> +
> +static inline uint16_t
> +vhost_dequeue_burst_1_1(struct virtio_net *dev, struct vhost_virtqueue *vq,
> + struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts,
> + uint16_t count)
> +{
> + uint16_t i;
> + uint16_t idx;
> + struct vring_desc_1_1 *desc = vq->desc_1_1;
> + int err;
> +
> + count = RTE_MIN(MAX_PKT_BURST, count);
> + for (i = 0; i < count; i++) {
> + idx = vq->last_used_idx & (vq->size - 1);
> + if (!desc_is_avail(vq, &desc[idx]))
> + break;
> + rte_smp_rmb();
> +
> + pkts[i] = rte_pktmbuf_alloc(mbuf_pool);
> + if (unlikely(pkts[i] == NULL)) {
> + RTE_LOG(ERR, VHOST_DATA,
> + "Failed to allocate memory for mbuf.\n");
> + break;
> + }
> +
> + err = dequeue_desc(dev, vq, mbuf_pool, pkts[i], desc);
> + if (unlikely(err)) {
> + rte_pktmbuf_free(pkts[i]);
> + break;
> + }
> + }
> +
> + rte_spinlock_unlock(&vq->access_lock);
Where is it locked? It looks unbalanced.
> +
> + return i;
> +}
> +
> uint16_t
> rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
> struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
>
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