git: eaf619fddcb2 - main - vtnet: improve interface capability handling

The branch main has been updated by tuexen:

URL: https://cgit.FreeBSD.org/src/commit/?id=eaf619fddcb21859311b895a0836da3171a01531

commit eaf619fddcb21859311b895a0836da3171a01531
Author:     Michael Tuexen <tuexen@FreeBSD.org>
AuthorDate: 2025-09-26 09:45:12 +0000
Commit:     Michael Tuexen <tuexen@FreeBSD.org>
CommitDate: 2025-09-26 10:12:51 +0000

    vtnet: improve interface capability handling
    
    Enable the handling of the IFCAP_RXCSUM_IPV6 handling by handling
    IFCAP_RXCSUM and IFCAP_RXCSUM_IPV6 as a pair. Also make clear, that
    software and hardware LRO require receive checksum offload.
    
    Reviewed by:            Timo Völker
    MFC after:              3 days
    Differential Revision:  https://reviews.freebsd.org/D52682
---
 share/man/man4/vtnet.4            |  4 +++-
 sys/dev/virtio/network/if_vtnet.c | 31 +++++++++++--------------------
 2 files changed, 14 insertions(+), 21 deletions(-)

diff --git a/share/man/man4/vtnet.4 b/share/man/man4/vtnet.4
index 0594ca70e99a..636ce4cc9b60 100644
--- a/share/man/man4/vtnet.4
+++ b/share/man/man4/vtnet.4
@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd September 16, 2025
+.Dd September 26, 2025
 .Dt VTNET 4
 .Os
 .Sh NAME
@@ -54,6 +54,8 @@ TCP segmentation offload (TSO), TCP large receive offload (LRO),
 hardware VLAN tag stripping/insertion features, a multicast hash filter,
 as well as Jumbo Frames (up to 9216 bytes), which can be
 configured via the interface MTU setting.
+TCP/UDP receive checksum offload cannot be configured independently for IPv4
+and IPv6.
 Selecting an MTU larger than 1500 bytes with the
 .Xr ifconfig 8
 utility configures the adapter to receive and transmit Jumbo Frames.
diff --git a/sys/dev/virtio/network/if_vtnet.c b/sys/dev/virtio/network/if_vtnet.c
index 528ff3372097..a4bb57adc609 100644
--- a/sys/dev/virtio/network/if_vtnet.c
+++ b/sys/dev/virtio/network/if_vtnet.c
@@ -1153,11 +1153,9 @@ vtnet_setup_interface(struct vtnet_softc *sc)
 	}
 
 	if (virtio_with_feature(dev, VIRTIO_NET_F_GUEST_CSUM)) {
-		if_setcapabilitiesbit(ifp, IFCAP_RXCSUM, 0);
-#ifdef notyet
 		/* BMV: Rx checksums not distinguished between IPv4 and IPv6. */
+		if_setcapabilitiesbit(ifp, IFCAP_RXCSUM, 0);
 		if_setcapabilitiesbit(ifp, IFCAP_RXCSUM_IPV6, 0);
-#endif
 
 		if (vtnet_tunable_int(sc, "fixup_needs_csum",
 		    vtnet_fixup_needs_csum) != 0)
@@ -1370,27 +1368,20 @@ vtnet_ioctl_ifcap(struct vtnet_softc *sc, struct ifreq *ifr)
 		if ((mask & (IFCAP_RXCSUM | IFCAP_RXCSUM_IPV6 | IFCAP_LRO)) ==
 		    IFCAP_LRO && vtnet_software_lro(sc))
 			reinit = update = 0;
-
-		if (mask & IFCAP_RXCSUM)
+		/*
+		 * VirtIO does not distinguish between receive checksum offload
+		 * for IPv4 and IPv6 packets, so treat them as a pair.
+		 */
+		if (mask & (IFCAP_RXCSUM | IFCAP_RXCSUM_IPV6)) {
 			if_togglecapenable(ifp, IFCAP_RXCSUM);
-		if (mask & IFCAP_RXCSUM_IPV6)
 			if_togglecapenable(ifp, IFCAP_RXCSUM_IPV6);
+		}
 		if (mask & IFCAP_LRO)
 			if_togglecapenable(ifp, IFCAP_LRO);
-
-		/*
-		 * VirtIO does not distinguish between IPv4 and IPv6 checksums
-		 * so treat them as a pair. Guest TSO (LRO) requires receive
-		 * checksums.
-		 */
-		if (if_getcapenable(ifp) & (IFCAP_RXCSUM | IFCAP_RXCSUM_IPV6)) {
-			if_setcapenablebit(ifp, IFCAP_RXCSUM, 0);
-#ifdef notyet
-			if_setcapenablebit(ifp, IFCAP_RXCSUM_IPV6, 0);
-#endif
-		} else
-			if_setcapenablebit(ifp, 0,
-			    (IFCAP_RXCSUM | IFCAP_RXCSUM_IPV6 | IFCAP_LRO));
+		/* Both SW and HW TCP LRO require receive checksum offload. */
+		if ((if_getcapenable(ifp) &
+		    (IFCAP_RXCSUM | IFCAP_RXCSUM_IPV6)) == 0)
+			if_setcapenablebit(ifp, 0, IFCAP_LRO);
 	}
 
 	if (mask & IFCAP_VLAN_HWFILTER) {