DPDK: Data Plane Development Kit

18.02.0-rc1
examples/vhost/virtio_net.c
/* SPDX-License-Identifier: BSD-3-Clause
* Copyright(c) 2010-2017 Intel Corporation
*/
#include <stdint.h>
#include <stdbool.h>
#include <linux/virtio_net.h>
#include <rte_mbuf.h>
#include <rte_memcpy.h>
#include <rte_vhost.h>
#include "main.h"
/*
* A very simple vhost-user net driver implementation, without
* any extra features being enabled, such as TSO and mrg-Rx.
*/
void
vs_vhost_net_setup(struct vhost_dev *dev)
{
uint16_t i;
int vid = dev->vid;
struct vhost_queue *queue;
RTE_LOG(INFO, VHOST_CONFIG,
"setting builtin vhost-user net driver\n");
rte_vhost_get_negotiated_features(vid, &dev->features);
if (dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF))
dev->hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
else
dev->hdr_len = sizeof(struct virtio_net_hdr);
rte_vhost_get_mem_table(vid, &dev->mem);
dev->nr_vrings = rte_vhost_get_vring_num(vid);
for (i = 0; i < dev->nr_vrings; i++) {
queue = &dev->queues[i];
queue->last_used_idx = 0;
queue->last_avail_idx = 0;
rte_vhost_get_vhost_vring(vid, i, &queue->vr);
}
}
void
vs_vhost_net_remove(struct vhost_dev *dev)
{
free(dev->mem);
}
enqueue_pkt(struct vhost_dev *dev, struct rte_vhost_vring *vr,
struct rte_mbuf *m, uint16_t desc_idx)
{
uint32_t desc_avail, desc_offset;
uint32_t mbuf_avail, mbuf_offset;
uint32_t cpy_len;
struct vring_desc *desc;
uint64_t desc_addr;
struct virtio_net_hdr virtio_hdr = {0, 0, 0, 0, 0, 0};
/* A counter to avoid desc dead loop chain */
uint16_t nr_desc = 1;
desc = &vr->desc[desc_idx];
desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
/*
* Checking of 'desc_addr' placed outside of 'unlikely' macro to avoid
* performance issue with some versions of gcc (4.8.4 and 5.3.0) which
* otherwise stores offset on the stack instead of in a register.
*/
if (unlikely(desc->len < dev->hdr_len) || !desc_addr)
return -1;
rte_prefetch0((void *)(uintptr_t)desc_addr);
/* write virtio-net header */
*(struct virtio_net_hdr *)(uintptr_t)desc_addr = virtio_hdr;
desc_offset = dev->hdr_len;
desc_avail = desc->len - dev->hdr_len;
mbuf_avail = rte_pktmbuf_data_len(m);
mbuf_offset = 0;
while (mbuf_avail != 0 || m->next != NULL) {
/* done with current mbuf, fetch next */
if (mbuf_avail == 0) {
m = m->next;
mbuf_offset = 0;
mbuf_avail = rte_pktmbuf_data_len(m);
}
/* done with current desc buf, fetch next */
if (desc_avail == 0) {
if ((desc->flags & VRING_DESC_F_NEXT) == 0) {
/* Room in vring buffer is not enough */
return -1;
}
if (unlikely(desc->next >= vr->size ||
++nr_desc > vr->size))
return -1;
desc = &vr->desc[desc->next];
desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
if (unlikely(!desc_addr))
return -1;
desc_offset = 0;
desc_avail = desc->len;
}
cpy_len = RTE_MIN(desc_avail, mbuf_avail);
rte_memcpy((void *)((uintptr_t)(desc_addr + desc_offset)),
rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
cpy_len);
mbuf_avail -= cpy_len;
mbuf_offset += cpy_len;
desc_avail -= cpy_len;
desc_offset += cpy_len;
}
return 0;
}
uint16_t
vs_enqueue_pkts(struct vhost_dev *dev, uint16_t queue_id,
struct rte_mbuf **pkts, uint32_t count)
{
struct vhost_queue *queue;
struct rte_vhost_vring *vr;
uint16_t avail_idx, free_entries, start_idx;
uint16_t desc_indexes[MAX_PKT_BURST];
uint16_t used_idx;
uint32_t i;
queue = &dev->queues[queue_id];
vr = &queue->vr;
avail_idx = *((volatile uint16_t *)&vr->avail->idx);
start_idx = queue->last_used_idx;
free_entries = avail_idx - start_idx;
count = RTE_MIN(count, free_entries);
count = RTE_MIN(count, (uint32_t)MAX_PKT_BURST);
if (count == 0)
return 0;
/* Retrieve all of the desc indexes first to avoid caching issues. */
rte_prefetch0(&vr->avail->ring[start_idx & (vr->size - 1)]);
for (i = 0; i < count; i++) {
used_idx = (start_idx + i) & (vr->size - 1);
desc_indexes[i] = vr->avail->ring[used_idx];
vr->used->ring[used_idx].id = desc_indexes[i];
vr->used->ring[used_idx].len = pkts[i]->pkt_len +
dev->hdr_len;
}
rte_prefetch0(&vr->desc[desc_indexes[0]]);
for (i = 0; i < count; i++) {
uint16_t desc_idx = desc_indexes[i];
int err;
err = enqueue_pkt(dev, vr, pkts[i], desc_idx);
if (unlikely(err)) {
used_idx = (start_idx + i) & (vr->size - 1);
vr->used->ring[used_idx].len = dev->hdr_len;
}
if (i + 1 < count)
rte_prefetch0(&vr->desc[desc_indexes[i+1]]);
}
*(volatile uint16_t *)&vr->used->idx += count;
queue->last_used_idx += count;
rte_vhost_vring_call(dev->vid, queue_id);
return count;
}
dequeue_pkt(struct vhost_dev *dev, struct rte_vhost_vring *vr,
struct rte_mbuf *m, uint16_t desc_idx,
struct rte_mempool *mbuf_pool)
{
struct vring_desc *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;
/* A counter to avoid desc dead loop chain */
uint32_t nr_desc = 1;
desc = &vr->desc[desc_idx];
if (unlikely((desc->len < dev->hdr_len)) ||
(desc->flags & VRING_DESC_F_INDIRECT))
return -1;
desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
if (unlikely(!desc_addr))
return -1;
/*
* We don't support ANY_LAYOUT, neither VERSION_1, meaning
* a Tx packet from guest must have 2 desc buffers at least:
* the first for storing the header and the others for
* storing the data.
*
* And since we don't support TSO, we could simply skip the
* header.
*/
desc = &vr->desc[desc->next];
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;
nr_desc += 1;
mbuf_offset = 0;
mbuf_avail = m->buf_len - RTE_PKTMBUF_HEADROOM;
while (1) {
cpy_len = RTE_MIN(desc_avail, mbuf_avail);
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 (unlikely(desc->next >= vr->size ||
++nr_desc > vr->size))
return -1;
desc = &vr->desc[desc->next];
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;
}
/*
* 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;
}
}
prev->data_len = mbuf_offset;
m->pkt_len += mbuf_offset;
return 0;
}
uint16_t
vs_dequeue_pkts(struct vhost_dev *dev, uint16_t queue_id,
struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
{
struct vhost_queue *queue;
struct rte_vhost_vring *vr;
uint32_t desc_indexes[MAX_PKT_BURST];
uint32_t used_idx;
uint32_t i = 0;
uint16_t free_entries;
uint16_t avail_idx;
queue = &dev->queues[queue_id];
vr = &queue->vr;
free_entries = *((volatile uint16_t *)&vr->avail->idx) -
queue->last_avail_idx;
if (free_entries == 0)
return 0;
/* Prefetch available and used ring */
avail_idx = queue->last_avail_idx & (vr->size - 1);
used_idx = queue->last_used_idx & (vr->size - 1);
rte_prefetch0(&vr->avail->ring[avail_idx]);
rte_prefetch0(&vr->used->ring[used_idx]);
count = RTE_MIN(count, MAX_PKT_BURST);
count = RTE_MIN(count, free_entries);
if (unlikely(count == 0))
return 0;
/*
* Retrieve all of the head indexes first and pre-update used entries
* to avoid caching issues.
*/
for (i = 0; i < count; i++) {
avail_idx = (queue->last_avail_idx + i) & (vr->size - 1);
used_idx = (queue->last_used_idx + i) & (vr->size - 1);
desc_indexes[i] = vr->avail->ring[avail_idx];
vr->used->ring[used_idx].id = desc_indexes[i];
vr->used->ring[used_idx].len = 0;
}
/* Prefetch descriptor index. */
rte_prefetch0(&vr->desc[desc_indexes[0]]);
for (i = 0; i < count; i++) {
int err;
if (likely(i + 1 < count))
rte_prefetch0(&vr->desc[desc_indexes[i + 1]]);
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_pkt(dev, vr, pkts[i], desc_indexes[i], mbuf_pool);
if (unlikely(err)) {
rte_pktmbuf_free(pkts[i]);
break;
}
}
queue->last_avail_idx += i;
queue->last_used_idx += i;
vr->used->idx += i;
rte_vhost_vring_call(dev->vid, queue_id);
return i;
}