virtio-net: correctly handle IPv6 TSO when supported

In the past, we were enabling IPv6 TSO in the TAP device but we were not
negotiating the flag with the guest driver. The previous commit cleaned
this up, by not setting gen::TUN_F_TSO6 when calling the TUNSETOFFLOAD
ioctl. This commit properly negotiates the feature and, if the guest
supports it, it enables it in the TAP device.

Signed-off-by: Babis Chalios <[email protected]>

Author: bchalios

src/vmm/src/devices/virtio/net/device.rs

@@ -22,7 +22,8 @@ use crate::devices::virtio::device::{DeviceState, IrqTrigger, IrqType, VirtioDev
 use crate::devices::virtio::gen::virtio_blk::VIRTIO_F_VERSION_1;
 use crate::devices::virtio::gen::virtio_net::{
     virtio_net_hdr_v1, VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM, VIRTIO_NET_F_GUEST_TSO4,
-    VIRTIO_NET_F_GUEST_UFO, VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_MAC,
+    VIRTIO_NET_F_GUEST_TSO6, VIRTIO_NET_F_GUEST_UFO, VIRTIO_NET_F_HOST_TSO4,
+    VIRTIO_NET_F_HOST_TSO6, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_MAC,
 };
 use crate::devices::virtio::gen::virtio_ring::VIRTIO_RING_F_EVENT_IDX;
 use crate::devices::virtio::iovec::IoVecBuffer;
@@ -155,8 +156,10 @@ impl Net {
         let mut avail_features = 1 << VIRTIO_NET_F_GUEST_CSUM
             | 1 << VIRTIO_NET_F_CSUM
             | 1 << VIRTIO_NET_F_GUEST_TSO4
+            | 1 << VIRTIO_NET_F_GUEST_TSO6
             | 1 << VIRTIO_NET_F_GUEST_UFO
             | 1 << VIRTIO_NET_F_HOST_TSO4
+            | 1 << VIRTIO_NET_F_HOST_TSO6
             | 1 << VIRTIO_NET_F_HOST_UFO
             | 1 << VIRTIO_F_VERSION_1
             | 1 << VIRTIO_RING_F_EVENT_IDX;
@@ -684,6 +687,12 @@ impl Net {
             gen::TUN_F_TSO4,
             VIRTIO_NET_F_GUEST_TSO4,
         );
+        add_if_supported(
+            &mut tap_features,
+            guest_supported_features,
+            gen::TUN_F_TSO6,
+            VIRTIO_NET_F_GUEST_TSO6,
+        );
 
         tap_features
     }
@@ -1010,9 +1019,11 @@ pub mod tests {
         let features = 1 << VIRTIO_NET_F_GUEST_CSUM
             | 1 << VIRTIO_NET_F_CSUM
             | 1 << VIRTIO_NET_F_GUEST_TSO4
+            | 1 << VIRTIO_NET_F_GUEST_TSO6
             | 1 << VIRTIO_NET_F_MAC
             | 1 << VIRTIO_NET_F_GUEST_UFO
             | 1 << VIRTIO_NET_F_HOST_TSO4
+            | 1 << VIRTIO_NET_F_HOST_TSO6
             | 1 << VIRTIO_NET_F_HOST_UFO
             | 1 << VIRTIO_F_VERSION_1
             | 1 << VIRTIO_RING_F_EVENT_IDX;
@@ -1037,9 +1048,12 @@ pub mod tests {
     // Test that `Net::build_tap_offload_features` creates the TAP offload features that we expect
     // it to do, based on the available guest features
     fn test_build_tap_offload_features_all() {
-        let supported_features =
-            1 << VIRTIO_NET_F_CSUM | 1 << VIRTIO_NET_F_GUEST_UFO | 1 << VIRTIO_NET_F_GUEST_TSO4;
-        let expected_tap_features = gen::TUN_F_CSUM | gen::TUN_F_UFO | gen::TUN_F_TSO4;
+        let supported_features = 1 << VIRTIO_NET_F_CSUM
+            | 1 << VIRTIO_NET_F_GUEST_UFO
+            | 1 << VIRTIO_NET_F_GUEST_TSO4
+            | 1 << VIRTIO_NET_F_GUEST_TSO6;
+        let expected_tap_features =
+            gen::TUN_F_CSUM | gen::TUN_F_UFO | gen::TUN_F_TSO4 | gen::TUN_F_TSO6;
         let supported_flags = Net::build_tap_offload_features(supported_features);
 
         assert_eq!(supported_flags, expected_tap_features);