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net/virtio-user: enable offloading

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When used with vhost kernel backend, we can offload at both directions.
  - From vhost kernel to virtio_user, the offload is enabled so that
    DPDK app can trust the flow is checksum-correct; and if DPDK app
    sends it through another port, the checksum needs to be
    recalculated or offloaded. It also applies to TSO.
  - From virtio_user to vhost_kernel, the offload is enabled so that
    kernel can trust the flow is L4-checksum-correct, no need to verify
    it; if kernel will consume it, DPDK app should make sure the
    l3-checksum is correctly set.

Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
This commit is contained in:
Jianfeng Tan 2017-01-13 12:18:39 +00:00 committed by Yuanhan Liu
parent e3b434818b
commit 5e97e42025
3 changed files with 59 additions and 2 deletions
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40
drivers/net/virtio/virtio_user/vhost_kernel.c
View File

@ -165,6 +165,28 @@ prepare_vhost_memory_kernel(void)
return vm;
}
/* with below features, vhost kernel does not need to do the checksum and TSO,
* these info will be passed to virtio_user through virtio net header.
*/
#define VHOST_KERNEL_GUEST_OFFLOADS_MASK \
((1ULL << VIRTIO_NET_F_GUEST_CSUM) | \
(1ULL << VIRTIO_NET_F_GUEST_TSO4) | \
(1ULL << VIRTIO_NET_F_GUEST_TSO6) | \
(1ULL << VIRTIO_NET_F_GUEST_ECN) | \
(1ULL << VIRTIO_NET_F_GUEST_UFO))
/* with below features, when flows from virtio_user to vhost kernel
* (1) if flows goes up through the kernel networking stack, it does not need
* to verify checksum, which can save CPU cycles;
* (2) if flows goes through a Linux bridge and outside from an interface
* (kernel driver), checksum and TSO will be done by GSO in kernel or even
* offloaded into real physical device.
*/
#define VHOST_KERNEL_HOST_OFFLOADS_MASK \
((1ULL << VIRTIO_NET_F_HOST_TSO4) | \
(1ULL << VIRTIO_NET_F_HOST_TSO6) | \
(1ULL << VIRTIO_NET_F_CSUM))
static int
vhost_kernel_ioctl(struct virtio_user_dev *dev,
enum vhost_user_request req,
@ -186,10 +208,15 @@ vhost_kernel_ioctl(struct virtio_user_dev *dev,
arg = (void *)vm;
}
/* We don't need memory protection here */
if (req_kernel == VHOST_SET_FEATURES)
if (req_kernel == VHOST_SET_FEATURES) {
/* We don't need memory protection here */
*(uint64_t *)arg &= ~(1ULL << VIRTIO_F_IOMMU_PLATFORM);
/* VHOST kernel does not know about below flags */
*(uint64_t *)arg &= ~VHOST_KERNEL_GUEST_OFFLOADS_MASK;
*(uint64_t *)arg &= ~VHOST_KERNEL_HOST_OFFLOADS_MASK;
}
for (i = 0; i < dev->max_queue_pairs; ++i) {
if (dev->vhostfds[i] < 0)
continue;
@ -199,6 +226,15 @@ vhost_kernel_ioctl(struct virtio_user_dev *dev,
break;
}
if (!ret && req_kernel == VHOST_GET_FEATURES) {
/* with tap as the backend, all these features are supported
* but not claimed by vhost-net, so we add them back when
* reporting to upper layer.
*/
*((uint64_t *)arg) |= VHOST_KERNEL_GUEST_OFFLOADS_MASK;
*((uint64_t *)arg) |= VHOST_KERNEL_HOST_OFFLOADS_MASK;
}
if (vm)
free(vm);

14
drivers/net/virtio/virtio_user/vhost_kernel_tap.c
View File

@ -50,6 +50,12 @@ vhost_kernel_open_tap(char **p_ifname, int hdr_size)
int sndbuf = INT_MAX;
struct ifreq ifr;
int tapfd;
unsigned int offload =
TUN_F_CSUM |
TUN_F_TSO4 |
TUN_F_TSO6 |
TUN_F_TSO_ECN |
TUN_F_UFO;
/* TODO:
* 1. verify we can get/set vnet_hdr_len, tap_probe_vnet_hdr_len
@ -106,6 +112,14 @@ vhost_kernel_open_tap(char **p_ifname, int hdr_size)
goto error;
}
/* TODO: before set the offload capabilities, we'd better (1) check
* negotiated features to see if necessary to offload; (2) query tap
* to see if it supports the offload capabilities.
*/
if (ioctl(tapfd, TUNSETOFFLOAD, offload) != 0)
PMD_DRV_LOG(ERR, "TUNSETOFFLOAD ioctl() failed: %s",
strerror(errno));
if (!(*p_ifname))
*p_ifname = strdup(ifr.ifr_name);

7
drivers/net/virtio/virtio_user/vhost_kernel_tap.h
View File

@ -54,6 +54,13 @@
#define IFF_ATTACH_QUEUE 0x0200
#define IFF_DETACH_QUEUE 0x0400
/* Features for GSO (TUNSETOFFLOAD). */
#define TUN_F_CSUM 0x01 /* You can hand me unchecksummed packets. */
#define TUN_F_TSO4 0x02 /* I can handle TSO for IPv4 packets */
#define TUN_F_TSO6 0x04 /* I can handle TSO for IPv6 packets */
#define TUN_F_TSO_ECN 0x08 /* I can handle TSO with ECN bits. */
#define TUN_F_UFO 0x10 /* I can handle UFO packets */
/* Constants */
#define PATH_NET_TUN "/dev/net/tun"