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Date: Fri, 2 Feb 2024 20:24:12 +0800
From: Yunsheng Lin <linyunsheng@...wei.com>
To: Jason Wang <jasowang@...hat.com>
CC: <davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>,
<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Michael S.
Tsirkin" <mst@...hat.com>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
<virtualization@...ts.linux.dev>
Subject: Re: [PATCH net-next v4 5/5] tools: virtio: introduce vhost_net_test
On 2024/2/2 12:05, Jason Wang wrote:
> On Tue, Jan 30, 2024 at 7:38 PM Yunsheng Lin <linyunsheng@...wei.com> wrote:
>>
>> introduce vhost_net_test basing on virtio_test to test
>> vhost_net changing in the kernel.
>
> Let's describe what kind of test is being done and how it is done here.
How about something like below:
This patch introduces testing for both vhost_net tx and rx.
Steps for vhost_net tx testing:
1. Prepare a out buf
2. Kick the vhost_net to do tx processing
3. Do the receiving in the tun side
4. verify the data received by tun is correct
Steps for vhost_net rx testing::
1. Prepare a in buf
2. Do the sending in the tun side
3. Kick the vhost_net to do rx processing
4. verify the data received by vhost_net is correct
>> +
>> +static int tun_alloc(struct vdev_info *dev)
>> +{
>> + struct ifreq ifr;
>> + int len = HDR_LEN;
>
> Any reason you can't just use the virtio_net uapi?
I didn't find a macro for that in include/uapi/linux/virtio_net.h.
Did you mean using something like below?
sizeof(struct virtio_net_hdr_mrg_rxbuf)
>
>> + int fd, e;
>> +
>> + fd = open("/dev/net/tun", O_RDWR);
>> + if (fd < 0) {
>> + perror("Cannot open /dev/net/tun");
>> + return fd;
>> + }
>> +
>> + memset(&ifr, 0, sizeof(ifr));
>> +
>> + ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
>> + snprintf(ifr.ifr_name, IFNAMSIZ, "tun_%d", getpid());
>> +
>> + e = ioctl(fd, TUNSETIFF, &ifr);
>> + if (e < 0) {
>> + perror("ioctl[TUNSETIFF]");
>> + close(fd);
>> + return e;
>> + }
>> +
>> + e = ioctl(fd, TUNSETVNETHDRSZ, &len);
>> + if (e < 0) {
>> + perror("ioctl[TUNSETVNETHDRSZ]");
>> + close(fd);
>> + return e;
>> + }
>> +
>> + e = ioctl(fd, SIOCGIFHWADDR, &ifr);
>> + if (e < 0) {
>> + perror("ioctl[SIOCGIFHWADDR]");
>> + close(fd);
>> + return e;
>> + }
>> +
>> + memcpy(dev->mac, &ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
>> + return fd;
>> +}
>> +
>> +static void vdev_create_socket(struct vdev_info *dev)
>> +{
>> + struct ifreq ifr;
>> +
>> + dev->sock = socket(AF_PACKET, SOCK_RAW, htons(TEST_PTYPE));
>> + assert(dev->sock != -1);
>> +
>> + snprintf(ifr.ifr_name, IFNAMSIZ, "tun_%d", getpid());
>
> Nit: it might be better to accept the device name instead of repeating
> the snprintf trick here, this would facilitate the future changes.
I am not sure I understand what did you mean by "accept the device name"
here.
The above is used to get ifindex of the tun netdevice created in
tun_alloc(), so that we can use it in vdev_send_packet() to send
a packet using the tun netdevice created in tun_alloc(). Is there
anything obvious I missed here?
>
>> + assert(ioctl(dev->sock, SIOCGIFINDEX, &ifr) >= 0);
>> +
>> + dev->ifindex = ifr.ifr_ifindex;
>> +
>> + /* Set the flags that bring the device up */
>> + assert(ioctl(dev->sock, SIOCGIFFLAGS, &ifr) >= 0);
>> + ifr.ifr_flags |= (IFF_UP | IFF_RUNNING);
>> + assert(ioctl(dev->sock, SIOCSIFFLAGS, &ifr) >= 0);
>> +}
>> +
>> +static void vdev_send_packet(struct vdev_info *dev)
>> +{
>> + char *sendbuf = dev->test_buf + HDR_LEN;
>> + struct sockaddr_ll saddrll = {0};
>> + int sockfd = dev->sock;
>> + int ret;
>> +
>> + saddrll.sll_family = PF_PACKET;
>> + saddrll.sll_ifindex = dev->ifindex;
>> + saddrll.sll_halen = ETH_ALEN;
>> + saddrll.sll_protocol = htons(TEST_PTYPE);
>> +
>> + ret = sendto(sockfd, sendbuf, TEST_BUF_LEN, 0,
>> + (struct sockaddr *)&saddrll,
>> + sizeof(struct sockaddr_ll));
>> + assert(ret >= 0);
>> +}
>> +
..
>> +
>> +static void vq_info_add(struct vdev_info *dev, int idx, int num, int fd)
>> +{
>> + struct vhost_vring_file backend = { .index = idx, .fd = fd };
>> + struct vq_info *info = &dev->vqs[idx];
>> + int r;
>> +
>> + info->idx = idx;
>> + info->kick = eventfd(0, EFD_NONBLOCK);
>> + info->call = eventfd(0, EFD_NONBLOCK);
>
> If we don't care about the callback, let's just avoid to set the call here?
>
> (As I see vq_callback is a NULL)
Sure, will remove the vq_callback related code.
>
>> + r = posix_memalign(&info->ring, 4096, vring_size(num, 4096));
>> + assert(r >= 0);
>> + vq_reset(info, num, &dev->vdev);
>> + vhost_vq_setup(dev, info);
>> + info->fds.fd = info->call;
>> + info->fds.events = POLLIN;
>> +
>> + r = ioctl(dev->control, VHOST_NET_SET_BACKEND, &backend);
>> + assert(!r);
>> +}
>> +
>> +static void vdev_info_init(struct vdev_info *dev, unsigned long long features)
>> +{
>> + struct ether_header *eh;
>> + int i, r;
>> +
>> + dev->vdev.features = features;
>> + INIT_LIST_HEAD(&dev->vdev.vqs);
>> + spin_lock_init(&dev->vdev.vqs_list_lock);
>> +
>> + dev->buf_size = (HDR_LEN + TEST_BUF_LEN) * 2;
>> + dev->buf = malloc(dev->buf_size);
>> + assert(dev->buf);
>> + dev->test_buf = dev->buf;
>> + dev->res_buf = dev->test_buf + HDR_LEN + TEST_BUF_LEN;
>> +
>> + memset(dev->test_buf, 0, HDR_LEN + TEST_BUF_LEN);
>> + eh = (struct ether_header *)(dev->test_buf + HDR_LEN);
>> + eh->ether_type = htons(TEST_PTYPE);
>> + memcpy(eh->ether_dhost, dev->mac, ETHER_ADDR_LEN);
>> + memcpy(eh->ether_shost, dev->mac, ETHER_ADDR_LEN);
>> +
>> + for (i = sizeof(*eh); i < TEST_BUF_LEN; i++)
>> + dev->test_buf[i + HDR_LEN] = (char)i;
>> +
>> + dev->control = open("/dev/vhost-net", O_RDWR);
>> + assert(dev->control >= 0);
>> +
>> + r = ioctl(dev->control, VHOST_SET_OWNER, NULL);
>> + assert(r >= 0);
>> +
>> + dev->mem = malloc(offsetof(struct vhost_memory, regions) +
>> + sizeof(dev->mem->regions[0]));
>> + assert(dev->mem);
>> + memset(dev->mem, 0, offsetof(struct vhost_memory, regions) +
>> + sizeof(dev->mem->regions[0]));
>> + dev->mem->nregions = 1;
>> + dev->mem->regions[0].guest_phys_addr = (long)dev->buf;
>> + dev->mem->regions[0].userspace_addr = (long)dev->buf;
>> + dev->mem->regions[0].memory_size = dev->buf_size;
>> +
>> + r = ioctl(dev->control, VHOST_SET_MEM_TABLE, dev->mem);
>> + assert(r >= 0);
>> +
>> + r = ioctl(dev->control, VHOST_SET_FEATURES, &features);
>> + assert(r >= 0);
>> +
>> + dev->nvqs = 2;
>> +}
>> +
>> +static void wait_for_interrupt(struct vq_info *vq)
>> +{
>> + unsigned long long val;
>> +
>> + poll(&vq->fds, 1, -1);
>> +
>> + if (vq->fds.revents & POLLIN)
>> + read(vq->fds.fd, &val, sizeof(val));
>> +}
>> +
>> +static void verify_res_buf(char *res_buf)
>> +{
>> + int i;
>> +
>> + for (i = ETHER_HDR_LEN; i < TEST_BUF_LEN; i++)
>> + assert(res_buf[i] == (char)i);
>> +}
>> +
>> +static void run_tx_test(struct vdev_info *dev, struct vq_info *vq,
>> + bool delayed, int batch, int bufs)
>
> It might be better to describe the test design briefly above as a
> comment. Or we can start from simple test logic and add sophisticated
> ones on top.
Does something described in the comment log as suggested by you make
sense to you?
Steps for vhost_net tx testing:
1. Prepare a out buf
2. Kick the vhost_net to do tx processing
3. Do the receiving in the tun side
4. verify the data received by tun is correct
>
>> +{
>> + const bool random_batch = batch == RANDOM_BATCH;
>> + long long spurious = 0;
>> + struct scatterlist sl;
>> + unsigned int len;
>> + int r;
>> +
>> + for (;;) {
>> + long started_before = vq->started;
>> + long completed_before = vq->completed;
>> +
>> + virtqueue_disable_cb(vq->vq);
>> + do {
>> + if (random_batch)
>> + batch = (random() % vq->vring.num) + 1;
>> +
>> + while (vq->started < bufs &&
>> + (vq->started - vq->completed) < batch) {
>> + sg_init_one(&sl, dev->test_buf, HDR_LEN + TEST_BUF_LEN);
>> + r = virtqueue_add_outbuf(vq->vq, &sl, 1,
>> + dev->test_buf + vq->started,
>> + GFP_ATOMIC);
>> + if (unlikely(r != 0)) {
>> + if (r == -ENOSPC &&
>> + vq->started > started_before)
>> + r = 0;
>> + else
>> + r = -1;
>> + break;
>> + }
>> +
>> + ++vq->started;
>> +
>> + if (unlikely(!virtqueue_kick(vq->vq))) {
>> + r = -1;
>> + break;
>> + }
>> + }
>> +
>> + if (vq->started >= bufs)
>> + r = -1;
>> +
>> + /* Flush out completed bufs if any */
>> + while (virtqueue_get_buf(vq->vq, &len)) {
>> + int n;
>> +
>> + n = recvfrom(dev->sock, dev->res_buf, TEST_BUF_LEN, 0, NULL, NULL);
>> + assert(n == TEST_BUF_LEN);
>> + verify_res_buf(dev->res_buf);
>> +
>> + ++vq->completed;
>> + r = 0;
>> + }
>> + } while (r == 0);
>> +
>> + if (vq->completed == completed_before && vq->started == started_before)
>> + ++spurious;
>> +
>> + assert(vq->completed <= bufs);
>> + assert(vq->started <= bufs);
>> + if (vq->completed == bufs)
>> + break;
>> +
>> + if (delayed) {
>> + if (virtqueue_enable_cb_delayed(vq->vq))
>> + wait_for_interrupt(vq);
>> + } else {
>> + if (virtqueue_enable_cb(vq->vq))
>> + wait_for_interrupt(vq);
>> + }
>> + }
>> + printf("TX spurious wakeups: 0x%llx started=0x%lx completed=0x%lx\n",
>> + spurious, vq->started, vq->completed);
>> +}
>> +
>> +static void run_rx_test(struct vdev_info *dev, struct vq_info *vq,
>> + bool delayed, int batch, int bufs)
>> +{
>> + const bool random_batch = batch == RANDOM_BATCH;
>> + long long spurious = 0;
>> + struct scatterlist sl;
>> + unsigned int len;
>> + int r;
>> +
>> + for (;;) {
>> + long started_before = vq->started;
>> + long completed_before = vq->completed;
>> +
>> + do {
>> + if (random_batch)
>> + batch = (random() % vq->vring.num) + 1;
>> +
>> + while (vq->started < bufs &&
>> + (vq->started - vq->completed) < batch) {
>> + sg_init_one(&sl, dev->res_buf, HDR_LEN + TEST_BUF_LEN);
>> +
>> + r = virtqueue_add_inbuf(vq->vq, &sl, 1,
>> + dev->res_buf + vq->started,
>> + GFP_ATOMIC);
>> + if (unlikely(r != 0)) {
>> + if (r == -ENOSPC &&
>
> Drivers usually maintain a #free_slots, this can help to avoid the
> trick for checking ENOSPC?
The above "(vq->started - vq->completed) < batch" seems to ensure that
the 'r' can't be '-ENOSPC'? We just need to ensure the batch <= desc_num,
and the 'r == -ENOSPC' checking seems to be unnecessary.
>
>> + vq->started > started_before)
>> + r = 0;
>> + else
>> + r = -1;
>> + break;
>> + }
>> +
>> + ++vq->started;
>> +
>> + vdev_send_packet(dev);
>> +
>> + if (unlikely(!virtqueue_kick(vq->vq))) {
>> + r = -1;
>> + break;
>> + }
>> + }
>> +
>> + if (vq->started >= bufs)
>> + r = -1;
>> +
>> + /* Flush out completed bufs if any */
>> + while (virtqueue_get_buf(vq->vq, &len)) {
>> + struct ether_header *eh;
>> +
>> + eh = (struct ether_header *)(dev->res_buf + HDR_LEN);
>> +
>> + /* tun netdev is up and running, ignore the
>> + * non-TEST_PTYPE packet.
>> + */
>
> I wonder if it's better to set up some kind of qdisc to avoid the
> unexpected packet here, or is it too complicated?
Yes, at least I don't know to do that yet.
>
> Thanks
>
> .
>
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