[dpdk-dev] [PATCH v3] net/virtio-user: check negotiated features before set

[eric zhang]

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 at windriver.com>

---
v3:
* make other offloading features depend on CSUM
* check IFF_VNET_HDR support when handling VHOST_GET_FEATURES

---
v2:
* don't return failure when failed to set offload to tap
* check if offloads available when handling VHOST_GET_FEATURES
---
 drivers/net/virtio/virtio_user/vhost_kernel.c     | 18 +++++---
 drivers/net/virtio/virtio_user/vhost_kernel_tap.c | 56 +++++++++++++++++------
 drivers/net/virtio/virtio_user/vhost_kernel_tap.h |  2 +-
 3 files changed, 54 insertions(+), 22 deletions(-)

diff --git a/drivers/net/virtio/virtio_user/vhost_kernel.c b/drivers/net/virtio/virtio_user/vhost_kernel.c
index dd24b6b..3502001 100644
--- a/drivers/net/virtio/virtio_user/vhost_kernel.c
+++ b/drivers/net/virtio/virtio_user/vhost_kernel.c
@@ -189,8 +189,8 @@ struct vhost_memory_kernel {
 	 (1ULL << VIRTIO_NET_F_HOST_TSO6) |	\
 	 (1ULL << VIRTIO_NET_F_CSUM))
 
-static int
-tap_supporte_mq(void)
+static unsigned int
+tap_support_features(void)
 {
 	int tapfd;
 	unsigned int tap_features;
@@ -209,7 +209,7 @@ struct vhost_memory_kernel {
 	}
 
 	close(tapfd);
-	return tap_features & IFF_MULTI_QUEUE;
+	return tap_features;
 }
 
 static int
@@ -223,6 +223,7 @@ struct vhost_memory_kernel {
 	struct vhost_memory_kernel *vm = NULL;
 	int vhostfd;
 	unsigned int queue_sel;
+	unsigned int features;
 
 	PMD_DRV_LOG(INFO, "%s", vhost_msg_strings[req]);
 
@@ -276,17 +277,20 @@ struct vhost_memory_kernel {
 	}
 
 	if (!ret && req_kernel == VHOST_GET_FEATURES) {
+		features = tap_support_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 (features & IFF_VNET_HDR) {
+			*((uint64_t *)arg) |= VHOST_KERNEL_GUEST_OFFLOADS_MASK;
+			*((uint64_t *)arg) |= VHOST_KERNEL_HOST_OFFLOADS_MASK;
+		}
 
 		/* vhost_kernel will not declare this feature, but it does
 		 * support multi-queue.
 		 */
-		if (tap_supporte_mq())
+		if (features & IFF_MULTI_QUEUE)
 			*(uint64_t *)arg |= (1ull << VIRTIO_NET_F_MQ);
 	}
 
@@ -381,7 +385,7 @@ struct vhost_memory_kernel {
 		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 d036428..e9ee774 100644
--- a/drivers/net/virtio/virtio_user/vhost_kernel_tap.c
+++ b/drivers/net/virtio/virtio_user/vhost_kernel_tap.c
@@ -45,21 +45,55 @@
 
 #include "vhost_kernel_tap.h"
 #include "../virtio_logs.h"
+#include "../virtio_pci.h"
+
+static int
+vhost_kernel_tap_set_offload(int fd, uint64_t features)
+{
+	unsigned int offload = 0;
+
+	if (features & (1ULL << VIRTIO_NET_F_GUEST_CSUM)) {
+		offload |= TUN_F_CSUM;
+		if (features & (1ULL << VIRTIO_NET_F_GUEST_TSO4))
+			offload |= TUN_F_TSO4;
+		if (features & (1ULL << VIRTIO_NET_F_GUEST_TSO6))
+			offload |= TUN_F_TSO6;
+		if (features & ((1ULL << VIRTIO_NET_F_GUEST_TSO4) |
+			(1ULL << VIRTIO_NET_F_GUEST_TSO6)) &&
+			(features & (1ULL << VIRTIO_NET_F_GUEST_ECN)))
+			offload |= TUN_F_TSO_ECN;
+		if (features & (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
@@ -119,13 +153,7 @@
 		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));
+	vhost_kernel_tap_set_offload(tapfd, features);
 
 	memset(&ifr, 0, sizeof(ifr));
 	ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;
diff --git a/drivers/net/virtio/virtio_user/vhost_kernel_tap.h b/drivers/net/virtio/virtio_user/vhost_kernel_tap.h
index 402f964..ea7a6c9 100644
--- a/drivers/net/virtio/virtio_user/vhost_kernel_tap.h
+++ b/drivers/net/virtio/virtio_user/vhost_kernel_tap.h
@@ -65,4 +65,4 @@
 #define PATH_NET_TUN	"/dev/net/tun"
 
 int vhost_kernel_open_tap(char **p_ifname, int hdr_size, int req_mq,
-			 const char *mac);
+			 const char *mac, uint64_t features);
-- 
1.8.3.1