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net: mana: Handle SKB if TX SGEs exceed hardware limit

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The MANA hardware supports a maximum of 30 scatter-gather entries (SGEs)
per TX WQE. Exceeding this limit can cause TX failures.
Add ndo_features_check() callback to validate SKB layout before
transmission. For GSO SKBs that would exceed the hardware SGE limit, clear
NETIF_F_GSO_MASK to enforce software segmentation in the stack.
Add a fallback in mana_start_xmit() to linearize non-GSO SKBs that still
exceed the SGE limit.

Also, Add ethtool counter for SKBs linearized

Co-developed-by: Dipayaan Roy <dipayanroy@linux.microsoft.com>
Signed-off-by: Dipayaan Roy <dipayanroy@linux.microsoft.com>
Signed-off-by: Aditya Garg <gargaditya@linux.microsoft.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Link: https://patch.msgid.link/1763464269-10431-2-git-send-email-gargaditya@linux.microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Aditya Garg
2025-11-18 03:11:08 -08:00
committed by Jakub Kicinski
parent 929ca3bcea
commit 934fa943b5
4 changed files with 48 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
drivers/net/ethernet/microsoft/mana/mana_en.c
View File

@@ -11,6 +11,7 @@
#include <linux/mm.h>
#include <linux/pci.h>
#include <linux/export.h>
#include <linux/skbuff.h>
#include <net/checksum.h>
#include <net/ip6_checksum.h>
@@ -329,6 +330,21 @@ netdev_tx_t mana_start_xmit(struct sk_buff *skb, struct net_device *ndev)
cq = &apc->tx_qp[txq_idx].tx_cq;
tx_stats = &txq->stats;
BUILD_BUG_ON(MAX_TX_WQE_SGL_ENTRIES != MANA_MAX_TX_WQE_SGL_ENTRIES);
if (MAX_SKB_FRAGS + 2 > MAX_TX_WQE_SGL_ENTRIES &&
skb_shinfo(skb)->nr_frags + 2 > MAX_TX_WQE_SGL_ENTRIES) {
/* GSO skb with Hardware SGE limit exceeded is not expected here
* as they are handled in mana_features_check() callback
*/
if (skb_linearize(skb)) {
netdev_warn_once(ndev, "Failed to linearize skb with nr_frags=%d and is_gso=%d\n",
skb_shinfo(skb)->nr_frags,
skb_is_gso(skb));
goto tx_drop_count;
}
apc->eth_stats.tx_linear_pkt_cnt++;
}
pkg.tx_oob.s_oob.vcq_num = cq->gdma_id;
pkg.tx_oob.s_oob.vsq_frame = txq->vsq_frame;
@@ -442,8 +458,6 @@ netdev_tx_t mana_start_xmit(struct sk_buff *skb, struct net_device *ndev)
}
}
WARN_ON_ONCE(pkg.wqe_req.num_sge > MAX_TX_WQE_SGL_ENTRIES);
if (pkg.wqe_req.num_sge <= ARRAY_SIZE(pkg.sgl_array)) {
pkg.wqe_req.sgl = pkg.sgl_array;
} else {
@@ -518,6 +532,25 @@ tx_drop:
return NETDEV_TX_OK;
}
#if (MAX_SKB_FRAGS + 2 > MANA_MAX_TX_WQE_SGL_ENTRIES)
static netdev_features_t mana_features_check(struct sk_buff *skb,
struct net_device *ndev,
netdev_features_t features)
{
if (skb_shinfo(skb)->nr_frags + 2 > MAX_TX_WQE_SGL_ENTRIES) {
/* Exceeds HW SGE limit.
* GSO case:
* Disable GSO so the stack will software-segment the skb
* into smaller skbs that fit the SGE budget.
* Non-GSO case:
* The xmit path will attempt skb_linearize() as a fallback.
*/
features &= ~NETIF_F_GSO_MASK;
}
return features;
}
#endif
static void mana_get_stats64(struct net_device *ndev,
struct rtnl_link_stats64 *st)
{
@@ -883,6 +916,9 @@ static const struct net_device_ops mana_devops = {
.ndo_open = mana_open,
.ndo_stop = mana_close,
.ndo_select_queue = mana_select_queue,
#if (MAX_SKB_FRAGS + 2 > MANA_MAX_TX_WQE_SGL_ENTRIES)
.ndo_features_check = mana_features_check,
#endif
.ndo_start_xmit = mana_start_xmit,
.ndo_validate_addr = eth_validate_addr,
.ndo_get_stats64 = mana_get_stats64,

2
drivers/net/ethernet/microsoft/mana/mana_ethtool.c
View File

@@ -18,6 +18,8 @@ static const struct mana_stats_desc mana_eth_stats[] = {
{"tx_cq_err", offsetof(struct mana_ethtool_stats, tx_cqe_err)},
{"tx_cqe_unknown_type", offsetof(struct mana_ethtool_stats,
tx_cqe_unknown_type)},
{"tx_linear_pkt_cnt", offsetof(struct mana_ethtool_stats,
tx_linear_pkt_cnt)},
{"rx_coalesced_err", offsetof(struct mana_ethtool_stats,
rx_coalesced_err)},
{"rx_cqe_unknown_type", offsetof(struct mana_ethtool_stats,

8
include/net/mana/gdma.h
View File

@@ -486,6 +486,8 @@ struct gdma_wqe {
#define INLINE_OOB_SMALL_SIZE 8
#define INLINE_OOB_LARGE_SIZE 24
#define MANA_MAX_TX_WQE_SGL_ENTRIES 30
#define MAX_TX_WQE_SIZE 512
#define MAX_RX_WQE_SIZE 256
@@ -592,6 +594,9 @@ enum {
#define GDMA_DRV_CAP_FLAG_1_HANDLE_RECONFIG_EQE BIT(17)
#define GDMA_DRV_CAP_FLAG_1_HW_VPORT_LINK_AWARE BIT(6)
/* Driver supports linearizing the skb when num_sge exceeds hardware limit */
#define GDMA_DRV_CAP_FLAG_1_SKB_LINEARIZE BIT(20)
/* Driver can send HWC periodically to query stats */
#define GDMA_DRV_CAP_FLAG_1_PERIODIC_STATS_QUERY BIT(21)
@@ -605,7 +610,8 @@ enum {
GDMA_DRV_CAP_FLAG_1_SELF_RESET_ON_EQE | \
GDMA_DRV_CAP_FLAG_1_HANDLE_RECONFIG_EQE | \
GDMA_DRV_CAP_FLAG_1_HW_VPORT_LINK_AWARE | \
GDMA_DRV_CAP_FLAG_1_PERIODIC_STATS_QUERY)
GDMA_DRV_CAP_FLAG_1_PERIODIC_STATS_QUERY | \
GDMA_DRV_CAP_FLAG_1_SKB_LINEARIZE)
#define GDMA_DRV_CAP_FLAGS2 0

1
include/net/mana/mana.h
View File

@@ -377,6 +377,7 @@ struct mana_ethtool_stats {
u64 wake_queue;
u64 tx_cqe_err;
u64 tx_cqe_unknown_type;
u64 tx_linear_pkt_cnt;
u64 rx_coalesced_err;
u64 rx_cqe_unknown_type;
};