Re: [dpdk-dev] [PATCH] net/virtio-user: check negotiated features before set

[Jens Freimann <jfreiman@redhat.com>]

On Thu, Aug 09, 2018 at 01:34:55PM -0500, Allain Legacy wrote:
>From: eric zhang <eric.zhang@windriver.com>
>
>This patch checks negotiated features to see if necessary to offload
>before set the tap device offload capabilities. It also checks if kernel
>support the TUNSETOFFLOAD operation.
>
>Signed-off-by: eric zhang <eric.zhang@windriver.com>
>Signed-off-by: Allain Legacy <allain.legacy@windriver.com>
>---
> drivers/net/virtio/virtio_user/vhost_kernel.c     |  2 +-
> drivers/net/virtio/virtio_user/vhost_kernel_tap.c | 56 +++++++++++++++++------
> drivers/net/virtio/virtio_user/vhost_kernel_tap.h |  2 +-
> 3 files changed, 44 insertions(+), 16 deletions(-)
>
>diff --git a/drivers/net/virtio/virtio_user/vhost_kernel.c b/drivers/net/virtio/virtio_user/vhost_kernel.c
>index b2444096c..66f2eaca9 100644
>--- a/drivers/net/virtio/virtio_user/vhost_kernel.c
>+++ b/drivers/net/virtio/virtio_user/vhost_kernel.c
>@@ -339,7 +339,7 @@ vhost_kernel_enable_queue_pair(struct virtio_user_dev *dev,
> 		hdr_size = sizeof(struct virtio_net_hdr);
>
> 	tapfd = vhost_kernel_open_tap(&dev->ifname, hdr_size, req_mq,
>-			 (char *)dev->mac_addr);
>+			 (char *)dev->mac_addr, dev->features);
> 	if (tapfd < 0) {
> 		PMD_DRV_LOG(ERR, "fail to open tap for vhost kernel");
> 		return -1;
>diff --git a/drivers/net/virtio/virtio_user/vhost_kernel_tap.c b/drivers/net/virtio/virtio_user/vhost_kernel_tap.c
>index 9ea7ade74..eda9fb78c 100644
>--- a/drivers/net/virtio/virtio_user/vhost_kernel_tap.c
>+++ b/drivers/net/virtio/virtio_user/vhost_kernel_tap.c
>@@ -16,21 +16,54 @@
>
> #include "vhost_kernel_tap.h"
> #include "../virtio_logs.h"
>+#include "../virtio_pci.h"
>+
>+static int
>+vhost_kernel_tap_set_offload(int fd, uint64_t feature)
>+{
>+	unsigned int offload = 0;
>+
>+	if (feature & (1ULL << VIRTIO_NET_F_GUEST_CSUM))
>+		offload |= TUN_F_CSUM;
>+	if (feature & (1ULL << VIRTIO_NET_F_GUEST_TSO4))
>+		offload |= TUN_F_TSO4;
>+	if (feature & (1ULL << VIRTIO_NET_F_GUEST_TSO6))
>+		offload |= TUN_F_TSO6;
>+	if (feature & ((1ULL << VIRTIO_NET_F_GUEST_TSO4) |
>+		(1ULL << VIRTIO_NET_F_GUEST_TSO6)) &&
>+		(feature & (1ULL << VIRTIO_NET_F_GUEST_ECN)))
>+		offload |= TUN_F_TSO_ECN;
>+	if (feature & (1ULL << VIRTIO_NET_F_GUEST_UFO))
>+		offload |= TUN_F_UFO;
>+
>+	if (offload != 0) {
>+		/* Check if our kernel supports TUNSETOFFLOAD */
>+		if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) {
>+			PMD_DRV_LOG(ERR, "Kernel does't support TUNSETOFFLOAD\n");
>+			return -ENOTSUP;
>+		}
>+
>+		if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
>+			offload &= ~TUN_F_UFO;
>+			if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
>+				PMD_DRV_LOG(ERR, "TUNSETOFFLOAD ioctl() failed: %s\n",
>+					strerror(errno));
>+				return -1;
>+			}
>+		}
>+	}
>+
>+	return 0;
>+}
>
> int
> vhost_kernel_open_tap(char **p_ifname, int hdr_size, int req_mq,
>-			 const char *mac)
>+			 const char *mac, uint64_t features)
> {
> 	unsigned int tap_features;
> 	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
>@@ -90,13 +123,8 @@ vhost_kernel_open_tap(char **p_ifname, int hdr_size, int req_mq,
> 		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 (vhost_kernel_tap_set_offload(tapfd, features) != 0)

Since we only check for != 0 we could just have it return a bool.
But it is just a nit.

Reviewed-by: Jens Freimann <jfreimann@redhat.com> 

regards,
Jens