Index: sys/dev/pci/if_ixl.c
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/dev/pci/if_ixl.c,v
diff -u -p -u -p -r1.102 if_ixl.c
--- sys/dev/pci/if_ixl.c	30 Oct 2024 18:02:45 -0000	1.102
+++ sys/dev/pci/if_ixl.c	3 Apr 2025 14:33:52 -0000
@@ -883,6 +883,8 @@ struct ixl_rx_wb_desc_16 {
 
 #define IXL_RX_DESC_PTYPE_SHIFT		30
 #define IXL_RX_DESC_PTYPE_MASK		(0xffULL << IXL_RX_DESC_PTYPE_SHIFT)
+#define IXL_RX_DESC_PTYPE_MAC_IPV4_TCP	26
+#define IXL_RX_DESC_PTYPE_MAC_IPV6_TCP	92
 
 #define IXL_RX_DESC_PLEN_SHIFT		38
 #define IXL_RX_DESC_PLEN_MASK		(0x3fffULL << IXL_RX_DESC_PLEN_SHIFT)
@@ -1975,6 +1977,11 @@ ixl_attach(struct device *parent, struct
 	    IFCAP_CSUM_TCPv4 | IFCAP_CSUM_UDPv4 |
 	    IFCAP_CSUM_TCPv6 | IFCAP_CSUM_UDPv6;
 	ifp->if_capabilities |= IFCAP_TSOv4 | IFCAP_TSOv6;
+	ifp->if_capabilities |= IFCAP_LRO;
+#if 0
+	/* for now tcplro at ixl(4) is default off */
+	ifp->if_xflags |= IFXF_LRO;
+#endif
 
 	ifmedia_init(&sc->sc_media, 0, ixl_media_change, ixl_media_status);
 
@@ -2949,6 +2956,14 @@ ixl_start(struct ifqueue *ifq)
 			continue;
 		}
 
+		if (ISSET(m->m_pkthdr.csum_flags, M_TCP_TSO)) {
+			struct ether_extracted ext;
+
+			ether_extract_headers(m, &ext);
+			KASSERT(m->m_pkthdr.len == ext.iplen + (ext.evh ?
+			    sizeof(*ext.evh) : sizeof(*ext.eh)));
+		}
+
 		bus_dmamap_sync(sc->sc_dmat, map, 0,
 		    map->dm_mapsize, BUS_DMASYNC_PREWRITE);
 
@@ -3255,9 +3270,11 @@ ixl_rxeof(struct ixl_softc *sc, struct i
 	struct ixl_rx_map *rxm;
 	bus_dmamap_t map;
 	unsigned int cons, prod;
+	struct mbuf_list mltcp = MBUF_LIST_INITIALIZER();
 	struct mbuf_list ml = MBUF_LIST_INITIALIZER();
 	struct mbuf *m;
 	uint64_t word;
+	unsigned int ptype;
 	unsigned int len;
 	unsigned int mask;
 	int done = 0;
@@ -3294,6 +3311,8 @@ ixl_rxeof(struct ixl_softc *sc, struct i
 		m = rxm->rxm_m;
 		rxm->rxm_m = NULL;
 
+		ptype = (word & IXL_RX_DESC_PTYPE_MASK)
+		    >> IXL_RX_DESC_PTYPE_SHIFT;
 		len = (word & IXL_RX_DESC_PLEN_MASK) >> IXL_RX_DESC_PLEN_SHIFT;
 		m->m_len = len;
 		m->m_pkthdr.len = 0;
@@ -3314,7 +3333,6 @@ ixl_rxeof(struct ixl_softc *sc, struct i
 					    lemtoh32(&rxd->filter_status);
 					m->m_pkthdr.csum_flags |= M_FLOWID;
 				}
-
 #if NVLAN > 0
 				if (ISSET(word, IXL_RX_DESC_L2TAG1P)) {
 					m->m_pkthdr.ether_vtag =
@@ -3322,9 +3340,14 @@ ixl_rxeof(struct ixl_softc *sc, struct i
 					SET(m->m_flags, M_VLANTAG);
 				}
 #endif
-
 				ixl_rx_checksum(m, word);
-				ml_enqueue(&ml, m);
+
+				if (ISSET(ifp->if_xflags, IFXF_LRO) &&
+				    (ptype == IXL_RX_DESC_PTYPE_MAC_IPV4_TCP ||
+				    ptype == IXL_RX_DESC_PTYPE_MAC_IPV6_TCP))
+					tcp_enqueue_lro(&mltcp, m);
+				else
+					ml_enqueue(&ml, m);
 			} else {
 				ifp->if_ierrors++; /* XXX */
 				m_freem(m);
@@ -3341,8 +3364,14 @@ ixl_rxeof(struct ixl_softc *sc, struct i
 	} while (cons != prod);
 
 	if (done) {
+		int livelocked = 0;
+
 		rxr->rxr_cons = cons;
+		if (ifiq_input(ifiq, &mltcp))
+			livelocked = 1;
 		if (ifiq_input(ifiq, &ml))
+			livelocked = 1;
+		if (livelocked)
 			if_rxr_livelocked(&rxr->rxr_acct);
 		ixl_rxfill(sc, rxr);
 	}
Index: sys/netinet/tcp_input.c
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/netinet/tcp_input.c,v
diff -u -p -u -p -r1.434 tcp_input.c
--- sys/netinet/tcp_input.c	10 Mar 2025 15:11:46 -0000	1.434
+++ sys/netinet/tcp_input.c	3 Apr 2025 14:33:52 -0000
@@ -84,6 +84,7 @@
 #include <net/if_var.h>
 #include <net/route.h>
 
+#include <netinet/if_ether.h>
 #include <netinet/in.h>
 #include <netinet/ip.h>
 #include <netinet/in_pcb.h>
@@ -4229,4 +4230,226 @@ syn_cache_respond(struct syn_cache *sc, 
 	}
 	in_pcbunref(inp);
 	return (error);
+}
+
+/*
+ * Check if mbuf contains TCP packet that could be merged
+ */
+int
+tcp_mergeable_single(struct mbuf *m, struct ether_extracted *ext)
+{
+	/* Don't merge packets with invalid TCP checksum. */
+	if (!ISSET(m->m_pkthdr.csum_flags, M_TCP_CSUM_IN_OK))
+		return 0;
+	/* Don't merge packets without RSS hash. */
+	if (!ISSET(m->m_pkthdr.csum_flags, M_FLOWID))
+		return 0;
+
+	if (ext->ip4) {
+		/* Don't merge packets with invalid IP header checksum. */
+		if (!ISSET(m->m_pkthdr.csum_flags, M_IPV4_CSUM_IN_OK))
+			return 0;
+		/* Don't merge IPv4 packets with option headers. */
+		if (ext->iphlen != sizeof(struct ip))
+			return 0;
+	}
+
+	/* Check TCP header. */
+	if (!ext->tcp)
+		return 0;
+
+	/* Don't merge empty segments. */
+	if (ext->paylen == 0)
+		return 0;
+	/* Just ACK and PUSH TCP flags are allowed. */
+	if (ISSET(ext->tcp->th_flags, TH_ACK|TH_PUSH) != ext->tcp->th_flags)
+		return 0;
+	/* TCP ACK flag has to be set. */
+	if (!ISSET(ext->tcp->th_flags, TH_ACK))
+		return 0;
+	return 1;
+}
+
+/*
+ * Check if head and tail are mergeable
+ */
+int
+tcp_mergeable_both(struct ether_extracted *head, struct ether_extracted *tail)
+{
+	/* Check IP header. */
+	if (head->ip4 && tail->ip4) {
+		/* Check IPv4 addresses. */
+		if (head->ip4->ip_src.s_addr != tail->ip4->ip_src.s_addr ||
+		    head->ip4->ip_dst.s_addr != tail->ip4->ip_dst.s_addr)
+			return 0;
+		/* Check max. IPv4 length. */
+		if (head->iplen + tail->iplen > IP_MAXPACKET)
+			return 0;
+	} else if (head->ip6 && tail->ip6) {
+		/* Check IPv6 addresses. */
+		if (!IN6_ARE_ADDR_EQUAL(&head->ip6->ip6_src,
+		    &tail->ip6->ip6_src) ||
+		    !IN6_ARE_ADDR_EQUAL(&head->ip6->ip6_dst,
+		    &tail->ip6->ip6_dst))
+			return 0;
+		/* Check max. IPv6 length. */
+		if ((head->iplen - head->iphlen) +
+		    (tail->iplen - tail->iphlen) > IPV6_MAXPACKET)
+			return 0;
+	} else
+		return 0;
+
+	/* Check TCP ports. */
+	if (head->tcp->th_sport != tail->tcp->th_sport ||
+	    head->tcp->th_dport != tail->tcp->th_dport)
+		return 0;
+	/* Check for contiguous segments. */
+	if (ntohl(head->tcp->th_seq) + head->paylen != ntohl(tail->tcp->th_seq))
+		return 0;
+
+	/* Ignore segments with different TCP options. */
+	if (head->tcphlen != tail->tcphlen)
+		return 0;
+	/* Check all TCP options */
+	if (head->tcphlen > sizeof(struct tcphdr)) {
+		u_char *hopt = (u_char *)head->tcp + sizeof(struct tcphdr);
+		u_char *topt = (u_char *)tail->tcp + sizeof(struct tcphdr);
+		int optsize = head->tcphlen - sizeof(struct tcphdr);
+		int optlen;
+
+		for (; optsize > 0; optsize -= optlen) {
+			/* Ignore segments with different TCP options. */
+			if (hopt[0] != topt[0])
+				return 0;
+			/* Get option length */
+			if (hopt[0] == TCPOPT_NOP) {
+				optlen = 1;
+			} else { 
+				if (optsize < 2)
+					return 0;	/* Illegal length */
+				optlen = hopt[1];
+				if (optlen > optsize)
+					return 0;	/* Illegal length */
+				if (hopt[1] != topt[1])
+					return 0;
+			}
+			if (hopt[0] != TCPOPT_NOP &&
+			    hopt[0] != TCPOPT_TIMESTAMP) {
+				return 0;	/* Unsupported TCP option */
+			}
+			hopt += optlen;
+			topt += optlen;
+		}
+	}
+	return 1;
+}
+
+/*
+ * Concatenation of head and tail mbuf.
+ */
+void
+tcp_concatenate(struct mbuf *mhead, struct ether_extracted *head,
+    struct mbuf *mtail, struct ether_extracted *tail)
+{
+	struct mbuf *m;
+	unsigned int hdrlen;
+
+	/* Remove ethernet padding. */
+	if (mhead->m_pkthdr.len > head->iplen)
+		m_adj(mhead, head->iplen - mhead->m_pkthdr.len);
+	/* Adjust IP header lenght. */
+	if (head->ip4) {
+		head->ip4->ip_len = htons(head->iplen + tail->paylen);
+	} else if (head->ip6) {
+		head->ip6->ip6_plen =
+		    htons(head->iplen - head->iphlen + tail->paylen);
+	}
+
+	/* Combine TCP flags from head and tail. */
+	if (ISSET(tail->tcp->th_flags, TH_PUSH))
+		SET(head->tcp->th_flags, TH_PUSH);
+	/* Adjust TCP header sequence space. */
+	head->tcp->th_ack = tail->tcp->th_ack;
+	head->tcp->th_win = tail->tcp->th_win;
+
+	/* Calculate header length of tail packet. */
+	hdrlen = sizeof(*tail->eh);
+	if (tail->evh)
+		hdrlen = sizeof(*tail->evh);
+	hdrlen += tail->iphlen;
+	hdrlen += tail->tcphlen;
+	/* Skip protocol headers in tail. */
+	m_adj(mtail, hdrlen);
+	CLR(mtail->m_flags, M_PKTHDR);
+
+	/* Concatenate */
+	for (m = mhead; m->m_next; m = m->m_next)
+		;
+	m->m_next = mtail;
+	mhead->m_pkthdr.len += tail->paylen;
+
+	/* Flag mbuf as TSO packet with MSS. */
+	if (!ISSET(mhead->m_pkthdr.csum_flags, M_TCP_TSO)) {
+		/* Set CSUM_OUT flags in case of forwarding. */
+		SET(mhead->m_pkthdr.csum_flags, M_TCP_CSUM_OUT);
+		head->tcp->th_sum = 0;
+		if (head->ip4) {
+			SET(mhead->m_pkthdr.csum_flags, M_IPV4_CSUM_OUT);
+			head->ip4->ip_sum = 0;
+		}
+		SET(mhead->m_pkthdr.csum_flags, M_TCP_TSO);
+		tcpstat_inc(tcps_inhwlro);
+		tcpstat_inc(tcps_inpktlro);	/* count head */
+	}
+	mhead->m_pkthdr.ph_mss = max(mhead->m_pkthdr.ph_mss, tail->paylen);
+	tcpstat_inc(tcps_inpktlro);	/* count tail */
+}
+
+void
+tcp_enqueue_lro(struct mbuf_list *ml, struct mbuf *mtail)
+{
+	struct mbuf		*mhead;
+	struct ether_extracted	 head, tail;
+
+	ether_extract_headers(mtail, &tail);
+	if (!tcp_mergeable_single(mtail, &tail)) {
+		mtail->m_pkthdr.ph_mss = 0;
+		goto dontmerge;
+	}
+	mtail->m_pkthdr.ph_mss = tail.paylen;
+
+	for (mhead = ml->ml_head; mhead != NULL; mhead = mhead->m_nextpkt) {
+		/* This packet was considered not mergable before. */
+		if (mhead->m_pkthdr.ph_mss == 0)
+			continue;
+
+		/* Use RSS hash to skip packets of different connections. */
+		if (mhead->m_pkthdr.ph_flowid != mtail->m_pkthdr.ph_flowid)
+			continue;
+		/* Don't merge packets of different VLANs with offloading. */
+		if (ISSET(mhead->m_flags, M_VLANTAG) !=
+		    ISSET(mtail->m_flags, M_VLANTAG))
+			continue;
+		if (ISSET(mhead->m_flags, M_VLANTAG) &&
+		    EVL_VLANOFTAG(mhead->m_pkthdr.ether_vtag) !=
+		    EVL_VLANOFTAG(mtail->m_pkthdr.ether_vtag))
+			continue;
+
+		ether_extract_headers(mhead, &head);
+		/* Don't merge packets of different VLANs without offloading. */
+		if (head.evh && tail.evh) {
+			if (EVL_VLANOFTAG(head.evh->evl_tag) !=
+			    EVL_VLANOFTAG(tail.evh->evl_tag))
+				continue;
+		} else if (head.evh || tail.evh)
+			continue;
+
+		if (!tcp_mergeable_both(&head, &tail))
+			continue;
+
+		tcp_concatenate(mhead, &head, mtail, &tail);
+		return;
+	}
+ dontmerge:
+	ml_enqueue(ml, mtail);
 }
Index: sys/netinet/tcp_var.h
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/netinet/tcp_var.h,v
diff -u -p -u -p -r1.186 tcp_var.h
--- sys/netinet/tcp_var.h	2 Mar 2025 21:28:32 -0000	1.186
+++ sys/netinet/tcp_var.h	3 Apr 2025 14:33:52 -0000
@@ -720,6 +720,7 @@ void	 tcp_init(void);
 int	 tcp_input(struct mbuf **, int *, int, int, struct netstack *);
 int	 tcp_mss(struct tcpcb *, int);
 void	 tcp_mss_update(struct tcpcb *);
+void	 tcp_enqueue_lro(struct mbuf_list *, struct mbuf *);
 u_int	 tcp_hdrsz(struct tcpcb *);
 void	 tcp_mtudisc(struct inpcb *, int);
 void	 tcp_mtudisc_increase(struct inpcb *, int);