[PATCH net-next v6 0/3] net: devmem: allow rx-buf-size > PAGE_SIZE per binding

[PATCH net-next v6 0/3] net: devmem: allow rx-buf-size > PAGE_SIZE per binding

[Bobby Eshleman]

Every devmem dmabuf binding hands the page_pool PAGE_SIZE niovs today.
On NICs that consume one descriptor per netmem, this caps a single RX
descriptor at PAGE_SIZE and burns CPU on buffer churn.

In this series, we add a bind-time netlink attribute,
NETDEV_A_DMABUF_RX_BUF_SIZE, that lets userspace request a larger niov
size (power of two >= PAGE_SIZE). Drivers must opt in via
queue_mgmt_ops.QCFG_RX_PAGE_SIZE.

Measurements:

Setup: kperf devmem RX/TX cuda, 4 flows, 64 MB messages, 60s, dctcp,
num-rx-queues=4, dmabuf-rx/tx-size-mb=2048, 10 runs per niov size,
mlx5.

   niov       RX dev Gbps   RX flow avg Gbps         app sys %
  -----  ----------------  -----------------  ----------------
     4K  300.63 +/- 53.21    75.16 +/- 13.30   54.15 +/- 10.23
    16K  321.35 +/- 28.20    80.34 +/-  7.05   41.05 +/-  8.87
    32K  347.63 +/-  2.20    86.91 +/-  0.55   44.54 +/-  3.51
    64K  332.11 +/- 14.26    83.03 +/-  3.56   35.47 +/-  3.11

RX app sys % drops ~19% from 4K to 64K.

kperf support (not yet merged):
https://github.com/facebookexperimental/kperf/commit/8837577f920876bce6986ec18869ac04439ebcd2

Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
---
Changes in v6:
- Rename rx-buf-size to rx-page-size (Jakub)
- Move the >= PAGE_SIZE check into the netlink policy; doit only checks
  is_power_of_2() (Jakub)
- Drop @ksft_disruptive from check_rx_large_niov() (Jakub)
- Link to v5: https://lore.kernel.org/r/20260708-tcpdm-large-niovs-v5-0-34bf6fac941b@meta.com

Changes in v5:
- removed unnecessary change from ssize_t to size_t (Mina)
- removed '--------' lines in the commit message (Paolo)
- removed commit msg about CONFIG_HUGETLB since that change was already
  merged
- Link to v4: https://lore.kernel.org/r/20260701-tcpdm-large-niovs-v4-0-ca4654f37570@meta.com

Changes in v4:
- ncdevmem: fix the possible overflow in ncdevmem (Sashiko)
- drop the udmabuf patch because the fix is now already in net-next
- silenced two pylint complaints in devmem_lib.py
- Link to v3: https://lore.kernel.org/r/20260612-tcpdm-large-niovs-v3-0-a3b693e76fcb@meta.com

Changes in v3:
- fix a bunch of non-reverse christmas tree declarations (Stan)
- remove extra uint32 cast for getpagesize() (Stan)
- remove overzealous strtoul checking (Stan)
- remove value checks that the kernel already performs on rx_buf_size
  (Stan)
- Link to v2: https://lore.kernel.org/r/20260611-tcpdm-large-niovs-v2-0-ee2bf15e7523@meta.com

Changes in v2:
- Use NL_SET_ERR_MSG_FMT for sg alignment failure details (Stan)
- Keep -E2BIG (not a direct ask, but seemed preferred, Stan)
- Update udmabuf commit message and comments explaining why
  "one sg ent per folio" is useful (Christian)
- Set/restore nr_hugepages in py harness (Stan)
- Link to v1: https://lore.kernel.org/r/20260603-tcpdm-large-niovs-v1-0-f37a4ac6726c@meta.com

---
Bobby Eshleman (3):
      net: devmem: allow rx-page-size > PAGE_SIZE per dmabuf binding
      selftests/net: ncdevmem: add -b option to set rx-page-size on bind
      selftests/net: devmem.py: add check_rx_large_niov

 Documentation/netlink/specs/netdev.yaml            | 17 +++++++
 include/uapi/linux/netdev.h                        |  1 +
 net/core/devmem.c                                  | 49 ++++++++++--------
 net/core/devmem.h                                  | 13 +++--
 net/core/netdev-genl-gen.c                         | 11 +++-
 net/core/netdev-genl-gen.h                         |  1 +
 net/core/netdev-genl.c                             | 18 ++++++-
 tools/include/uapi/linux/netdev.h                  |  1 +
 tools/testing/selftests/drivers/net/hw/devmem.py   | 11 +++-
 .../testing/selftests/drivers/net/hw/devmem_lib.py | 59 +++++++++++++++++++++-
 tools/testing/selftests/drivers/net/hw/ncdevmem.c  | 36 +++++++++++--
 .../testing/selftests/drivers/net/hw/nk_devmem.py  | 10 +++-
 12 files changed, 190 insertions(+), 37 deletions(-)
---
base-commit: 89d8006259b81dd25c962f6cc8d7ab268d6ea426
change-id: 20260602-tcpdm-large-niovs-56523a3a1077

Best regards,
-- 
Bobby Eshleman <bobbyeshleman@meta.com>

[PATCH net-next v6 1/3] net: devmem: allow rx-page-size > PAGE_SIZE per dmabuf binding

[Bobby Eshleman]

From: Bobby Eshleman <bobbyeshleman@meta.com>

Every devmem dmabuf binding today hands the page_pool PAGE_SIZE niovs.
This caps a single RX descriptor at PAGE_SIZE, burning CPU on buffer
churn for large flows.

Add a bind-time netlink attribute, NETDEV_A_DMABUF_RX_PAGE_SIZE, that
lets userspace request a larger niov size. The value must be a power of
two >= PAGE_SIZE.

Measurements:
Setup: kperf in devmem RX/TX cuda mode, 4 flows, 64 MB messages, 60s,
dctcp, num-rx-queues=4, dmabuf-rx/tx-size-mb=2048, 10 runs per niov
size, mlx5.

CPU Util:

   niov        net sirq %        net idle %         app sys %        app idle %
  -----  ----------------  ----------------  ----------------  ----------------
     4K   62.38 +/-  8.27   33.40 +/-  7.51   54.15 +/- 10.23   43.67 +/- 10.53
    16K   58.91 +/-  5.35   35.23 +/-  5.88   41.05 +/-  8.87   56.42 +/-  9.24
    32K   64.12 +/-  0.68   31.09 +/-  1.48   44.54 +/-  3.51   52.63 +/-  3.65
    64K   54.69 +/-  5.54   39.67 +/-  5.81   35.47 +/-  3.11   61.97 +/-  3.27

RX app sys % drops ~19% from 4K to 64K.

Throughput:

   niov       RX dev Gbps   RX flow avg Gbps
  -----  ----------------  -----------------
     4K  300.63 +/- 53.21    75.16 +/- 13.30
    16K  321.35 +/- 28.20    80.34 +/-  7.05
    32K  347.63 +/-  2.20    86.91 +/-  0.55
    64K  332.11 +/- 14.26    83.03 +/-  3.56

Throughput seems to increase, but the stdev is pretty wide so could just
be noise.

kperf support (not yet merged):
https://github.com/facebookexperimental/kperf/commit/8837577f920876bce6986ec18869ac04439ebcd2

Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Mina Almasry <almasrymina@google.com>
---
 Documentation/netlink/specs/netdev.yaml | 17 ++++++++++++
 include/uapi/linux/netdev.h             |  1 +
 net/core/devmem.c                       | 49 +++++++++++++++++++--------------
 net/core/devmem.h                       | 13 ++++++---
 net/core/netdev-genl-gen.c              | 11 ++++++--
 net/core/netdev-genl-gen.h              |  1 +
 net/core/netdev-genl.c                  | 18 ++++++++++--
 tools/include/uapi/linux/netdev.h       |  1 +
 8 files changed, 83 insertions(+), 28 deletions(-)

diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
index 5f143da7458c..1ee64342df11 100644
--- a/Documentation/netlink/specs/netdev.yaml
+++ b/Documentation/netlink/specs/netdev.yaml
@@ -6,6 +6,12 @@ doc: >-
   netdev configuration over generic netlink.
 
 definitions:
+  -
+    type: const
+    name: page-size
+    value: 0  # dummy: codegen needs a number, real value is the PAGE_SIZE macro (header)
+    header: asm/page.h
+    scope: kernel
   -
     type: flags
     name: xdp-act
@@ -598,6 +604,16 @@ attribute-sets:
         type: u32
         checks:
           min: 1
+      -
+        name: rx-page-size
+        doc: |
+          Size in bytes of each device page the NIC writes into from the bound
+          dmabuf. Must be a power of two and >= PAGE_SIZE; defaults to
+          PAGE_SIZE.
+        type: u32
+        checks:
+          min: page-size
+          max: u32-max
 
 operations:
   list:
@@ -812,6 +828,7 @@ operations:
             - ifindex
             - fd
             - queues
+            - rx-page-size
         reply:
           attributes:
             - id
diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h
index 2f3ab75e8cc0..35ff083221c7 100644
--- a/include/uapi/linux/netdev.h
+++ b/include/uapi/linux/netdev.h
@@ -219,6 +219,7 @@ enum {
 	NETDEV_A_DMABUF_QUEUES,
 	NETDEV_A_DMABUF_FD,
 	NETDEV_A_DMABUF_ID,
+	NETDEV_A_DMABUF_RX_PAGE_SIZE,
 
 	__NETDEV_A_DMABUF_MAX,
 	NETDEV_A_DMABUF_MAX = (__NETDEV_A_DMABUF_MAX - 1)
diff --git a/net/core/devmem.c b/net/core/devmem.c
index 957d6b96216b..b036f14cb23a 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -46,7 +46,7 @@ static dma_addr_t net_devmem_get_dma_addr(const struct net_iov *niov)
 
 	owner = net_devmem_iov_to_chunk_owner(niov);
 	return owner->base_dma_addr +
-	       ((dma_addr_t)net_iov_idx(niov) << PAGE_SHIFT);
+	       ((dma_addr_t)net_iov_idx(niov) << owner->binding->niov_shift);
 }
 
 static void net_devmem_dmabuf_binding_release(struct percpu_ref *ref)
@@ -93,13 +93,14 @@ net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding)
 	ssize_t offset;
 	ssize_t index;
 
-	dma_addr = gen_pool_alloc_owner(binding->chunk_pool, PAGE_SIZE,
+	dma_addr = gen_pool_alloc_owner(binding->chunk_pool,
+					1UL << binding->niov_shift,
 					(void **)&owner);
 	if (!dma_addr)
 		return NULL;
 
 	offset = dma_addr - owner->base_dma_addr;
-	index = offset / PAGE_SIZE;
+	index = offset >> binding->niov_shift;
 	niov = &owner->area.niovs[index];
 
 	niov->desc.pp_magic = 0;
@@ -113,12 +114,13 @@ void net_devmem_free_dmabuf(struct net_iov *niov)
 {
 	struct net_devmem_dmabuf_binding *binding = net_devmem_iov_binding(niov);
 	unsigned long dma_addr = net_devmem_get_dma_addr(niov);
+	size_t niov_size = 1UL << binding->niov_shift;
 
 	if (WARN_ON(!gen_pool_has_addr(binding->chunk_pool, dma_addr,
-				       PAGE_SIZE)))
+				       niov_size)))
 		return;
 
-	gen_pool_free(binding->chunk_pool, dma_addr, PAGE_SIZE);
+	gen_pool_free(binding->chunk_pool, dma_addr, niov_size);
 }
 
 void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
@@ -163,6 +165,9 @@ int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
 	u32 xa_idx;
 	int err;
 
+	if (binding->niov_shift != PAGE_SHIFT)
+		mp_params.rx_page_size = 1U << binding->niov_shift;
+
 	err = netif_mp_open_rxq(dev, rxq_idx, &mp_params, extack);
 	if (err)
 		return err;
@@ -184,10 +189,12 @@ struct net_devmem_dmabuf_binding *
 net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
 		       struct device *dma_dev,
 		       enum dma_data_direction direction,
-		       unsigned int dmabuf_fd, struct netdev_nl_sock *priv,
+		       unsigned int dmabuf_fd, unsigned int niov_shift,
+		       struct netdev_nl_sock *priv,
 		       struct netlink_ext_ack *extack)
 {
 	struct net_devmem_dmabuf_binding *binding;
+	size_t niov_size = 1UL << niov_shift;
 	static u32 id_alloc_next;
 	struct scatterlist *sg;
 	struct dma_buf *dmabuf;
@@ -213,6 +220,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
 
 	binding->dev = dev;
 	binding->vdev = vdev;
+	binding->niov_shift = niov_shift;
 	xa_init_flags(&binding->bound_rxqs, XA_FLAGS_ALLOC);
 
 	err = percpu_ref_init(&binding->ref,
@@ -248,18 +256,14 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
 			goto err_unmap;
 		}
 		binding->tx_vec = kvmalloc_objs(struct net_iov *,
-						dmabuf->size / PAGE_SIZE);
+						dmabuf->size >> niov_shift);
 		if (!binding->tx_vec) {
 			err = -ENOMEM;
 			goto err_unmap;
 		}
 	}
 
-	/* For simplicity we expect to make PAGE_SIZE allocations, but the
-	 * binding can be much more flexible than that. We may be able to
-	 * allocate MTU sized chunks here. Leave that for future work...
-	 */
-	binding->chunk_pool = gen_pool_create(PAGE_SHIFT,
+	binding->chunk_pool = gen_pool_create(niov_shift,
 					      dev_to_node(&dev->dev));
 	if (!binding->chunk_pool) {
 		err = -ENOMEM;
@@ -273,9 +277,12 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
 		size_t len = sg_dma_len(sg);
 		struct net_iov *niov;
 
-		if (!IS_ALIGNED(len, PAGE_SIZE)) {
+		if (!IS_ALIGNED(dma_addr, niov_size) ||
+		    !IS_ALIGNED(len, niov_size)) {
 			err = -EINVAL;
-			NL_SET_ERR_MSG(extack, "dma-buf SG length must be PAGE_SIZE aligned");
+			NL_SET_ERR_MSG_FMT(extack,
+					   "dmabuf sg entry (addr=%pad, len=%zu) not aligned to niov size %zu",
+					   &dma_addr, len, niov_size);
 			goto err_free_chunks;
 		}
 
@@ -288,7 +295,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
 
 		owner->area.base_virtual = virtual;
 		owner->base_dma_addr = dma_addr;
-		owner->area.num_niovs = len / PAGE_SIZE;
+		owner->area.num_niovs = len >> niov_shift;
 		owner->binding = binding;
 
 		err = gen_pool_add_owner(binding->chunk_pool, dma_addr,
@@ -313,7 +320,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
 			page_pool_set_dma_addr_netmem(net_iov_to_netmem(niov),
 						      net_devmem_get_dma_addr(niov));
 			if (direction == DMA_TO_DEVICE)
-				binding->tx_vec[owner->area.base_virtual / PAGE_SIZE + i] = niov;
+				binding->tx_vec[(owner->area.base_virtual >> niov_shift) + i] = niov;
 		}
 
 		virtual += len;
@@ -430,13 +437,15 @@ struct net_iov *
 net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding,
 		       size_t virt_addr, size_t *off, size_t *size)
 {
+	size_t niov_size = 1UL << binding->niov_shift;
+
 	if (virt_addr >= binding->dmabuf->size)
 		return NULL;
 
-	*off = virt_addr % PAGE_SIZE;
-	*size = PAGE_SIZE - *off;
+	*off = virt_addr & (niov_size - 1);
+	*size = niov_size - *off;
 
-	return binding->tx_vec[virt_addr / PAGE_SIZE];
+	return binding->tx_vec[virt_addr >> binding->niov_shift];
 }
 
 /*** "Dmabuf devmem memory provider" ***/
@@ -454,7 +463,7 @@ int mp_dmabuf_devmem_init(struct page_pool *pool)
 	pool->dma_sync = false;
 	pool->dma_sync_for_cpu = false;
 
-	if (pool->p.order != 0)
+	if (pool->p.order != binding->niov_shift - PAGE_SHIFT)
 		return -E2BIG;
 
 	net_devmem_dmabuf_binding_get(binding);
diff --git a/net/core/devmem.h b/net/core/devmem.h
index 3852a56036cb..4a293a7d1149 100644
--- a/net/core/devmem.h
+++ b/net/core/devmem.h
@@ -71,6 +71,8 @@ struct net_devmem_dmabuf_binding {
 	 */
 	struct net_iov **tx_vec;
 
+	unsigned int niov_shift;
+
 	struct work_struct unbind_w;
 };
 
@@ -93,7 +95,8 @@ struct net_devmem_dmabuf_binding *
 net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
 		       struct device *dma_dev,
 		       enum dma_data_direction direction,
-		       unsigned int dmabuf_fd, struct netdev_nl_sock *priv,
+		       unsigned int dmabuf_fd, unsigned int niov_shift,
+		       struct netdev_nl_sock *priv,
 		       struct netlink_ext_ack *extack);
 struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id);
 void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding);
@@ -122,10 +125,11 @@ static inline u32 net_devmem_iov_binding_id(const struct net_iov *niov)
 
 static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
 {
-	struct net_iov_area *owner = net_iov_owner(niov);
+	struct dmabuf_genpool_chunk_owner *co =
+		net_devmem_iov_to_chunk_owner(niov);
 
-	return owner->base_virtual +
-	       ((unsigned long)net_iov_idx(niov) << PAGE_SHIFT);
+	return net_iov_owner(niov)->base_virtual +
+	       ((unsigned long)net_iov_idx(niov) << co->binding->niov_shift);
 }
 
 static inline bool
@@ -175,6 +179,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, void *vdev,
 		       struct device *dma_dev,
 		       enum dma_data_direction direction,
 		       unsigned int dmabuf_fd,
+		       unsigned int niov_shift,
 		       struct netdev_nl_sock *priv,
 		       struct netlink_ext_ack *extack)
 {
diff --git a/net/core/netdev-genl-gen.c b/net/core/netdev-genl-gen.c
index d18c89b5a6c7..f83790341eae 100644
--- a/net/core/netdev-genl-gen.c
+++ b/net/core/netdev-genl-gen.c
@@ -11,6 +11,7 @@
 
 #include <uapi/linux/netdev.h>
 #include <net/netdev_netlink.h>
+#include <asm/page.h>
 
 /* Integer value ranges */
 static const struct netlink_range_validation netdev_a_page_pool_id_range = {
@@ -27,6 +28,11 @@ static const struct netlink_range_validation netdev_a_napi_defer_hard_irqs_range
 	.max	= S32_MAX,
 };
 
+static const struct netlink_range_validation netdev_a_dmabuf_rx_page_size_range = {
+	.min	= PAGE_SIZE,
+	.max	= U32_MAX,
+};
+
 /* Common nested types */
 const struct nla_policy netdev_lease_nl_policy[NETDEV_A_LEASE_NETNS_ID + 1] = {
 	[NETDEV_A_LEASE_IFINDEX] = NLA_POLICY_MIN(NLA_U32, 1),
@@ -106,10 +112,11 @@ static const struct nla_policy netdev_qstats_get_nl_policy[NETDEV_A_QSTATS_SCOPE
 };
 
 /* NETDEV_CMD_BIND_RX - do */
-static const struct nla_policy netdev_bind_rx_nl_policy[NETDEV_A_DMABUF_FD + 1] = {
+static const struct nla_policy netdev_bind_rx_nl_policy[NETDEV_A_DMABUF_RX_PAGE_SIZE + 1] = {
 	[NETDEV_A_DMABUF_IFINDEX] = NLA_POLICY_MIN(NLA_U32, 1),
 	[NETDEV_A_DMABUF_FD] = { .type = NLA_U32, },
 	[NETDEV_A_DMABUF_QUEUES] = NLA_POLICY_NESTED(netdev_queue_id_nl_policy),
+	[NETDEV_A_DMABUF_RX_PAGE_SIZE] = NLA_POLICY_FULL_RANGE(NLA_U32, &netdev_a_dmabuf_rx_page_size_range),
 };
 
 /* NETDEV_CMD_NAPI_SET - do */
@@ -219,7 +226,7 @@ static const struct genl_split_ops netdev_nl_ops[] = {
 		.cmd		= NETDEV_CMD_BIND_RX,
 		.doit		= netdev_nl_bind_rx_doit,
 		.policy		= netdev_bind_rx_nl_policy,
-		.maxattr	= NETDEV_A_DMABUF_FD,
+		.maxattr	= NETDEV_A_DMABUF_RX_PAGE_SIZE,
 		.flags		= GENL_UNS_ADMIN_PERM | GENL_CMD_CAP_DO,
 	},
 	{
diff --git a/net/core/netdev-genl-gen.h b/net/core/netdev-genl-gen.h
index d71b435d72c1..3fae88e8f5c5 100644
--- a/net/core/netdev-genl-gen.h
+++ b/net/core/netdev-genl-gen.h
@@ -12,6 +12,7 @@
 
 #include <uapi/linux/netdev.h>
 #include <net/netdev_netlink.h>
+#include <asm/page.h>
 
 /* Common nested types */
 extern const struct nla_policy netdev_lease_nl_policy[NETDEV_A_LEASE_NETNS_ID + 1];
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index c15d8d4ca1f8..0eea4ee22f24 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -1013,6 +1013,7 @@ netdev_nl_get_dma_dev(struct net_device *netdev, unsigned long *rxq_bitmap,
 int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info)
 {
 	struct net_devmem_dmabuf_binding *binding;
+	unsigned int niov_shift = PAGE_SHIFT;
 	u32 ifindex, dmabuf_fd, rxq_idx;
 	struct netdev_nl_sock *priv;
 	struct net_device *netdev;
@@ -1030,6 +1031,18 @@ int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info)
 	ifindex = nla_get_u32(info->attrs[NETDEV_A_DEV_IFINDEX]);
 	dmabuf_fd = nla_get_u32(info->attrs[NETDEV_A_DMABUF_FD]);
 
+	if (info->attrs[NETDEV_A_DMABUF_RX_PAGE_SIZE]) {
+		u32 rx_page_size = nla_get_u32(info->attrs[NETDEV_A_DMABUF_RX_PAGE_SIZE]);
+
+		if (!is_power_of_2(rx_page_size)) {
+			NL_SET_ERR_MSG_ATTR(info->extack,
+					    info->attrs[NETDEV_A_DMABUF_RX_PAGE_SIZE],
+					    "rx-page-size must be a power of 2");
+			return -EINVAL;
+		}
+		niov_shift = ilog2(rx_page_size);
+	}
+
 	priv = genl_sk_priv_get(&netdev_nl_family, NETLINK_CB(skb).sk);
 	if (IS_ERR(priv))
 		return PTR_ERR(priv);
@@ -1080,7 +1093,8 @@ int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info)
 	}
 
 	binding = net_devmem_bind_dmabuf(netdev, NULL, dma_dev, DMA_FROM_DEVICE,
-					 dmabuf_fd, priv, info->extack);
+					 dmabuf_fd, niov_shift, priv,
+					 info->extack);
 	if (IS_ERR(binding)) {
 		err = PTR_ERR(binding);
 		goto err_rxq_bitmap;
@@ -1221,7 +1235,7 @@ int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
 	binding = net_devmem_bind_dmabuf(bind_dev,
 					 bind_dev != netdev ? netdev : NULL,
 					 dma_dev, DMA_TO_DEVICE, dmabuf_fd,
-					 priv, info->extack);
+					 PAGE_SHIFT, priv, info->extack);
 	if (IS_ERR(binding)) {
 		err = PTR_ERR(binding);
 		goto err_unlock_bind_dev;
diff --git a/tools/include/uapi/linux/netdev.h b/tools/include/uapi/linux/netdev.h
index 2f3ab75e8cc0..35ff083221c7 100644
--- a/tools/include/uapi/linux/netdev.h
+++ b/tools/include/uapi/linux/netdev.h
@@ -219,6 +219,7 @@ enum {
 	NETDEV_A_DMABUF_QUEUES,
 	NETDEV_A_DMABUF_FD,
 	NETDEV_A_DMABUF_ID,
+	NETDEV_A_DMABUF_RX_PAGE_SIZE,
 
 	__NETDEV_A_DMABUF_MAX,
 	NETDEV_A_DMABUF_MAX = (__NETDEV_A_DMABUF_MAX - 1)

-- 
2.53.0-Meta

[PATCH net-next v6 2/3] selftests/net: ncdevmem: add -b option to set rx-page-size on bind

[Bobby Eshleman]

From: Bobby Eshleman <bobbyeshleman@meta.com>

Add -b <bytes> to request a non-default niov size via
NETDEV_A_DMABUF_RX_PAGE_SIZE. When the value exceeds PAGE_SIZE,
udmabuf_alloc() switches to an MFD_HUGETLB-backed memfd so each 2 MB
hugepage produces one naturally-aligned sg entry.

Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
---
 tools/testing/selftests/drivers/net/hw/ncdevmem.c | 36 +++++++++++++++++++++--
 1 file changed, 33 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
index d96e8a3b5a65..ffe8eb05fac0 100644
--- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c
+++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
@@ -40,6 +40,7 @@
 
 #include <linux/uio.h>
 #include <stdarg.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -61,6 +62,7 @@
 #include <sys/time.h>
 
 #include <linux/memfd.h>
+#include <sys/param.h>
 #include <linux/dma-buf.h>
 #include <linux/errqueue.h>
 #include <linux/udmabuf.h>
@@ -79,6 +81,7 @@
 #define PAGE_SHIFT 12
 #define TEST_PREFIX "ncdevmem"
 #define NUM_PAGES 16000
+#define MB(x) ((x) << 20)
 
 #ifndef MSG_SOCK_DEVMEM
 #define MSG_SOCK_DEVMEM 0x2000000
@@ -100,6 +103,7 @@ static unsigned int dmabuf_id;
 static uint32_t tx_dmabuf_id;
 static int waittime_ms = 500;
 static bool fail_on_linear;
+static uint32_t rx_page_size;
 
 /* System state loaded by current_config_load() */
 #define MAX_FLOWS	8
@@ -142,6 +146,7 @@ static struct memory_buffer *udmabuf_alloc(size_t size)
 {
 	struct udmabuf_create create;
 	struct memory_buffer *ctx;
+	unsigned int memfd_flags;
 	int ret;
 
 	ctx = malloc(sizeof(*ctx));
@@ -156,9 +161,14 @@ static struct memory_buffer *udmabuf_alloc(size_t size)
 		goto err_free_ctx;
 	}
 
-	ctx->memfd = memfd_create("udmabuf-test", MFD_ALLOW_SEALING);
+	memfd_flags = MFD_ALLOW_SEALING;
+	if (rx_page_size > getpagesize())
+		memfd_flags |= MFD_HUGETLB | MFD_HUGE_2MB;
+
+	ctx->memfd = memfd_create("udmabuf-test", memfd_flags);
 	if (ctx->memfd < 0) {
-		pr_err("[skip,no-memfd]");
+		pr_err("[skip,no-memfd%s]",
+		       (memfd_flags & MFD_HUGETLB) ? " (need hugepages)" : "");
 		goto err_close_dev;
 	}
 
@@ -168,6 +178,11 @@ static struct memory_buffer *udmabuf_alloc(size_t size)
 		goto err_close_memfd;
 	}
 
+	if (memfd_flags & MFD_HUGETLB) {
+		size = roundup(size, MB(2));
+		ctx->size = size;
+	}
+
 	ret = ftruncate(ctx->memfd, size);
 	if (ret == -1) {
 		pr_err("[FAIL,memfd-truncate]");
@@ -699,6 +714,8 @@ static int bind_rx_queue(unsigned int ifindex, unsigned int dmabuf_fd,
 	netdev_bind_rx_req_set_ifindex(req, ifindex);
 	netdev_bind_rx_req_set_fd(req, dmabuf_fd);
 	__netdev_bind_rx_req_set_queues(req, queues, n_queue_index);
+	if (rx_page_size)
+		netdev_bind_rx_req_set_rx_page_size(req, rx_page_size);
 
 	rsp = netdev_bind_rx(*ys, req);
 	if (!rsp) {
@@ -1411,7 +1428,7 @@ int main(int argc, char *argv[])
 	int is_server = 0, opt;
 	int ret, err = 1;
 
-	while ((opt = getopt(argc, argv, "Lls:c:p:v:q:t:f:z:n")) != -1) {
+	while ((opt = getopt(argc, argv, "Lls:c:p:v:q:t:f:z:nb:")) != -1) {
 		switch (opt) {
 		case 'L':
 			fail_on_linear = true;
@@ -1446,6 +1463,19 @@ int main(int argc, char *argv[])
 		case 'n':
 			skip_config = 1;
 			break;
+		case 'b': {
+			unsigned long val;
+
+			errno = 0;
+			val = strtoul(optarg, NULL, 0);
+			if ((val == ULONG_MAX && errno == ERANGE) ||
+			    val > UINT32_MAX) {
+				pr_err("invalid rx_page_size: %s", optarg);
+				return 1;
+			}
+			rx_page_size = val;
+			break;
+		}
 		case '?':
 			fprintf(stderr, "unknown option: %c\n", optopt);
 			break;

-- 
2.53.0-Meta

[PATCH net-next v6 3/3] selftests/net: devmem.py: add check_rx_large_niov

[Bobby Eshleman]

From: Bobby Eshleman <bobbyeshleman@meta.com>

Add a new devmem test case for binding the dmabuf with rx-page-size=16K.
The test sweeps RX payload sizes straddling the niov boundary to cover
the sub-niov, exact-niov, and multi-niov RX paths.

Silence pylint invalid-name (`with open() as f`) and too-many-arguments
(ncdevmem_rx grew to 6 args) at file scope.

Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
---
 tools/testing/selftests/drivers/net/hw/devmem.py   | 11 +++-
 .../testing/selftests/drivers/net/hw/devmem_lib.py | 59 +++++++++++++++++++++-
 .../testing/selftests/drivers/net/hw/nk_devmem.py  | 10 +++-
 3 files changed, 74 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/hw/devmem.py b/tools/testing/selftests/drivers/net/hw/devmem.py
index 031cf9905f65..82c11ffc4add 100755
--- a/tools/testing/selftests/drivers/net/hw/devmem.py
+++ b/tools/testing/selftests/drivers/net/hw/devmem.py
@@ -2,7 +2,8 @@
 # SPDX-License-Identifier: GPL-2.0
 
 from os import path
-from devmem_lib import setup_test, run_rx, run_tx, run_tx_chunks, run_rx_hds
+from devmem_lib import (setup_test, run_rx, run_tx, run_tx_chunks, run_rx_hds,
+                        run_rx_large_niov)
 from lib.py import ksft_run, ksft_exit, ksft_disruptive
 from lib.py import NetDrvEpEnv
 
@@ -30,11 +31,17 @@ def check_rx_hds(cfg) -> None:
     run_rx_hds(cfg)
 
 
+def check_rx_large_niov(cfg) -> None:
+    """Run the devmem RX test with rx-page-size = 16 KiB."""
+    run_rx_large_niov(cfg)
+
+
 def main() -> None:
     """Run the devmem test cases."""
     with NetDrvEpEnv(__file__) as cfg:
         setup_test(cfg, path.abspath(path.dirname(__file__) + "/ncdevmem"))
-        ksft_run([check_rx, check_tx, check_tx_chunks, check_rx_hds],
+        ksft_run([check_rx, check_tx, check_tx_chunks, check_rx_hds,
+                  check_rx_large_niov],
                  args=(cfg,))
     ksft_exit()
 
diff --git a/tools/testing/selftests/drivers/net/hw/devmem_lib.py b/tools/testing/selftests/drivers/net/hw/devmem_lib.py
index 0921ff03eb81..6c932018b463 100644
--- a/tools/testing/selftests/drivers/net/hw/devmem_lib.py
+++ b/tools/testing/selftests/drivers/net/hw/devmem_lib.py
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
+# pylint: disable=invalid-name,too-many-arguments
 """Shared helpers for devmem TCP selftests."""
 
 import re
@@ -8,7 +9,7 @@ from lib.py import (bkg, cmd, defer, ethtool, rand_port, wait_port_listen,
                     NetdevFamily)
 
 
-def require_devmem(cfg):
+def require_devmem(cfg, rx_page_size=0):
     """Probe ncdevmem on cfg.ifname and SKIP the test if devmem isn't supported."""
     if not hasattr(cfg, "devmem_probed"):
         probe_command = f"{cfg.bin_local} -f {cfg.ifname}"
@@ -18,6 +19,19 @@ def require_devmem(cfg):
     if not cfg.devmem_supported:
         raise KsftSkipEx("Test requires devmem support")
 
+    if rx_page_size > 0:
+        if not hasattr(cfg, "devmem_rx_page_size_probed"):
+            cfg.devmem_rx_page_size_probed = {}
+
+        if rx_page_size not in cfg.devmem_rx_page_size_probed:
+            probe_command = f"{cfg.bin_local} -f {cfg.ifname} -b {rx_page_size}"
+            cfg.devmem_rx_page_size_probed[rx_page_size] = \
+                cmd(probe_command, fail=False, shell=True).ret == 0
+
+        if not cfg.devmem_rx_page_size_probed[rx_page_size]:
+            raise KsftSkipEx(
+                f"Test requires devmem rx-page-size={rx_page_size} support")
+
 
 def configure_nic(cfg):
     """Channels, rings, RSS, queue lease for netkit devmem."""
@@ -76,7 +90,8 @@ def set_flow_rule(cfg, port):
     return int(re.search(r'ID (\d+)', output).group(1))
 
 
-def ncdevmem_rx(cfg, port, verify=True, fail_on_linear=False, flow_steer=False):
+def ncdevmem_rx(cfg, port, verify=True, fail_on_linear=False, flow_steer=False,
+                rx_page_size=0):
     """Build the ncdevmem RX listener command."""
     if hasattr(cfg, 'netns'):
         flow_rule_id = set_flow_rule(cfg, port)
@@ -96,6 +111,8 @@ def ncdevmem_rx(cfg, port, verify=True, fail_on_linear=False, flow_steer=False):
         extras.append("-v 7")
     if fail_on_linear:
         extras.append("-L")
+    if rx_page_size > 0:
+        extras.append(f"-b {rx_page_size}")
 
     parts = [cfg.bin_local, "-l", f"-f {ifname}", f"-s {addr}",
              f"-p {port}", *extras]
@@ -202,6 +219,44 @@ def run_tx_chunks(cfg):
     ksft_eq(socat.stdout.strip(), "hello\nworld")
 
 
+def _restore_nr_hugepages(hp_file, nr_hugepages):
+    with open(hp_file, 'w', encoding='utf-8') as f:
+        f.write(str(nr_hugepages))
+
+
+def run_rx_large_niov(cfg):
+    """Run the devmem RX test with a large niov (rx-page-size > PAGE_SIZE).
+
+    Sweep payload sizes that straddle the niov boundary: below, equal to,
+    and above rx_page_size, to exercise sub-niov, exact-niov, and multi-niov
+    RX paths.
+    """
+    hp_file = "/proc/sys/vm/nr_hugepages"
+    with open(hp_file, 'r+', encoding='utf-8') as f:
+        nr_hugepages = int(f.read().strip())
+        if nr_hugepages < 64:
+            f.seek(0)
+            f.write("64")
+            defer(_restore_nr_hugepages, hp_file, nr_hugepages)
+    require_devmem(cfg, rx_page_size=16384)
+    configure_nic(cfg)
+    netns = getattr(cfg, "netns", None)
+
+    for size in [1024, 4096, 8192, 16384, 32768, 65536]:
+        port = rand_port()
+        socat = socat_send(cfg, port)
+        listen_cmd = ncdevmem_rx(cfg, port,
+                                 flow_steer=not netns,
+                                 rx_page_size=16384)
+        data_pipe = (f"yes $(echo -e \x01\x02\x03\x04\x05\x06) | "
+                     f"head -c {size} | {socat}")
+        with bkg(listen_cmd, exit_wait=True, ns=netns) as ncdevmem:
+            wait_port_listen(port, proto="tcp", ns=netns)
+            cmd(data_pipe, host=cfg.remote, shell=True)
+        ksft_eq(ncdevmem.ret, 0,
+                f"large-niov failed for payload size {size}")
+
+
 def run_rx_hds(cfg):
     """Run the HDS test by running devmem RX across a segment size sweep."""
     require_devmem(cfg)
diff --git a/tools/testing/selftests/drivers/net/hw/nk_devmem.py b/tools/testing/selftests/drivers/net/hw/nk_devmem.py
index 300ed2a70ab4..61c6f31f01e5 100755
--- a/tools/testing/selftests/drivers/net/hw/nk_devmem.py
+++ b/tools/testing/selftests/drivers/net/hw/nk_devmem.py
@@ -3,7 +3,8 @@
 """Test devmem TCP with netkit."""
 
 import os
-from devmem_lib import setup_test, run_rx, run_tx, run_tx_chunks, run_rx_hds
+from devmem_lib import (setup_test, run_rx, run_tx, run_tx_chunks, run_rx_hds,
+                        run_rx_large_niov)
 from lib.py import ksft_run, ksft_exit, ksft_disruptive
 from lib.py import NetDrvContEnv
 
@@ -31,6 +32,11 @@ def check_nk_rx_hds(cfg) -> None:
     run_rx_hds(cfg)
 
 
+def check_nk_rx_large_niov(cfg) -> None:
+    """Run the devmem RX large-niov test through netkit."""
+    run_rx_large_niov(cfg)
+
+
 def main() -> None:
     """Run the netkit devmem test cases."""
     with NetDrvContEnv(__file__, rxqueues=2, primary_rx_redirect=True) as cfg:
@@ -38,7 +44,7 @@ def main() -> None:
                    os.path.join(os.path.dirname(os.path.abspath(__file__)),
                                 "ncdevmem"))
         ksft_run([check_nk_rx, check_nk_tx, check_nk_tx_chunks,
-                  check_nk_rx_hds], args=(cfg,))
+                  check_nk_rx_hds, check_nk_rx_large_niov], args=(cfg,))
     ksft_exit()
 
 

-- 
2.53.0-Meta

Re: [PATCH net-next v6 1/3] net: devmem: allow rx-page-size > PAGE_SIZE per dmabuf binding

[Nikolay Aleksandrov]

On Fri, Jul 24, 2026 at 02:21:15PM -0700, Bobby Eshleman wrote:
> From: Bobby Eshleman <bobbyeshleman@meta.com>
> 
> Every devmem dmabuf binding today hands the page_pool PAGE_SIZE niovs.
> This caps a single RX descriptor at PAGE_SIZE, burning CPU on buffer
> churn for large flows.
> 
> Add a bind-time netlink attribute, NETDEV_A_DMABUF_RX_PAGE_SIZE, that
> lets userspace request a larger niov size. The value must be a power of
> two >= PAGE_SIZE.
> 
> Measurements:
> Setup: kperf in devmem RX/TX cuda mode, 4 flows, 64 MB messages, 60s,
> dctcp, num-rx-queues=4, dmabuf-rx/tx-size-mb=2048, 10 runs per niov
> size, mlx5.
> 
> CPU Util:
> 
>    niov        net sirq %        net idle %         app sys %        app idle %
>   -----  ----------------  ----------------  ----------------  ----------------
>      4K   62.38 +/-  8.27   33.40 +/-  7.51   54.15 +/- 10.23   43.67 +/- 10.53
>     16K   58.91 +/-  5.35   35.23 +/-  5.88   41.05 +/-  8.87   56.42 +/-  9.24
>     32K   64.12 +/-  0.68   31.09 +/-  1.48   44.54 +/-  3.51   52.63 +/-  3.65
>     64K   54.69 +/-  5.54   39.67 +/-  5.81   35.47 +/-  3.11   61.97 +/-  3.27
> 
> RX app sys % drops ~19% from 4K to 64K.
> 
> Throughput:
> 
>    niov       RX dev Gbps   RX flow avg Gbps
>   -----  ----------------  -----------------
>      4K  300.63 +/- 53.21    75.16 +/- 13.30
>     16K  321.35 +/- 28.20    80.34 +/-  7.05
>     32K  347.63 +/-  2.20    86.91 +/-  0.55
>     64K  332.11 +/- 14.26    83.03 +/-  3.56
> 
> Throughput seems to increase, but the stdev is pretty wide so could just
> be noise.
> 
> kperf support (not yet merged):
> https://github.com/facebookexperimental/kperf/commit/8837577f920876bce6986ec18869ac04439ebcd2
> 
> Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
> Acked-by: Stanislav Fomichev <sdf@fomichev.me>
> Reviewed-by: Mina Almasry <almasrymina@google.com>
> ---
>  Documentation/netlink/specs/netdev.yaml | 17 ++++++++++++
>  include/uapi/linux/netdev.h             |  1 +
>  net/core/devmem.c                       | 49 +++++++++++++++++++--------------
>  net/core/devmem.h                       | 13 ++++++---
>  net/core/netdev-genl-gen.c              | 11 ++++++--
>  net/core/netdev-genl-gen.h              |  1 +
>  net/core/netdev-genl.c                  | 18 ++++++++++--
>  tools/include/uapi/linux/netdev.h       |  1 +
>  8 files changed, 83 insertions(+), 28 deletions(-)
> 

LGTM,
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>

Cheers,
 Nik

Re: [PATCH net-next v6 2/3] selftests/net: ncdevmem: add -b option to set rx-page-size on bind

[Nikolay Aleksandrov]

On Fri, Jul 24, 2026 at 02:21:16PM -0700, Bobby Eshleman wrote:
> From: Bobby Eshleman <bobbyeshleman@meta.com>
> 
> Add -b <bytes> to request a non-default niov size via
> NETDEV_A_DMABUF_RX_PAGE_SIZE. When the value exceeds PAGE_SIZE,
> udmabuf_alloc() switches to an MFD_HUGETLB-backed memfd so each 2 MB
> hugepage produces one naturally-aligned sg entry.
> 
> Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
> Acked-by: Stanislav Fomichev <sdf@fomichev.me>
> ---
>  tools/testing/selftests/drivers/net/hw/ncdevmem.c | 36 +++++++++++++++++++++--
>  1 file changed, 33 insertions(+), 3 deletions(-)
> 
 
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>

Re: [PATCH net-next v6 3/3] selftests/net: devmem.py: add check_rx_large_niov

[Nikolay Aleksandrov]

On Fri, Jul 24, 2026 at 02:21:17PM -0700, Bobby Eshleman wrote:
> From: Bobby Eshleman <bobbyeshleman@meta.com>
> 
> Add a new devmem test case for binding the dmabuf with rx-page-size=16K.
> The test sweeps RX payload sizes straddling the niov boundary to cover
> the sub-niov, exact-niov, and multi-niov RX paths.
> 
> Silence pylint invalid-name (`with open() as f`) and too-many-arguments
> (ncdevmem_rx grew to 6 args) at file scope.
> 
> Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
> Acked-by: Stanislav Fomichev <sdf@fomichev.me>
> ---
>  tools/testing/selftests/drivers/net/hw/devmem.py   | 11 +++-
>  .../testing/selftests/drivers/net/hw/devmem_lib.py | 59 +++++++++++++++++++++-
>  .../testing/selftests/drivers/net/hw/nk_devmem.py  | 10 +++-
>  3 files changed, 74 insertions(+), 6 deletions(-)
> 
 
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>

Re: [PATCH net-next v6 1/3] net: devmem: allow rx-page-size > PAGE_SIZE per dmabuf binding

[Jakub Kicinski]

On Fri, 24 Jul 2026 14:21:15 -0700 Bobby Eshleman wrote:
> +    value: 0  # dummy: codegen needs a number, real value is the PAGE_SIZE macro (header)

yamllint says:

  12:81     error    line too long (89 > 80 characters)  (line-length)

Re: [PATCH net-next v6 3/3] selftests/net: devmem.py: add check_rx_large_niov

[Jakub Kicinski]

On Fri, 24 Jul 2026 14:21:17 -0700 Bobby Eshleman wrote:
> From: Bobby Eshleman <bobbyeshleman@meta.com>
> 
> Add a new devmem test case for binding the dmabuf with rx-page-size=16K.
> The test sweeps RX payload sizes straddling the niov boundary to cover
> the sub-niov, exact-niov, and multi-niov RX paths.
> 
> Silence pylint invalid-name (`with open() as f`) and too-many-arguments
> (ncdevmem_rx grew to 6 args) at file scope.
> 
> Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
> Acked-by: Stanislav Fomichev <sdf@fomichev.me>

Hm, odd. In NIPA we're getting:

TAP version 13
1..1
# timeout set to 0
# selftests: drivers/net/hw: devmem.py
# TAP version 13
# 1..5
# ok 1 devmem.check_rx # SKIP marked as disruptive
# ok 2 devmem.check_tx # SKIP marked as disruptive
# ok 3 devmem.check_tx_chunks # SKIP marked as disruptive
# ok 4 devmem.check_rx_hds # SKIP Test requires devmem support
# ok 5 devmem.check_rx_large_niov # SKIP Test requires devmem support
# # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:5 error:0
ok 1 selftests: drivers/net/hw: devmem.py
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0

https://netdev.bots.linux.dev/logs/hwksft/BCM57508/results/755681/config
driver: bnxt
fw: 237.1.148.0

Any idea?

Re: [PATCH net-next v6 3/3] selftests/net: devmem.py: add check_rx_large_niov

[Bobby Eshleman]

On Wed, Jul 29, 2026 at 07:16:49PM -0700, Jakub Kicinski wrote:
> On Fri, 24 Jul 2026 14:21:17 -0700 Bobby Eshleman wrote:
> > From: Bobby Eshleman <bobbyeshleman@meta.com>
> > 
> > Add a new devmem test case for binding the dmabuf with rx-page-size=16K.
> > The test sweeps RX payload sizes straddling the niov boundary to cover
> > the sub-niov, exact-niov, and multi-niov RX paths.
> > 
> > Silence pylint invalid-name (`with open() as f`) and too-many-arguments
> > (ncdevmem_rx grew to 6 args) at file scope.
> > 
> > Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
> > Acked-by: Stanislav Fomichev <sdf@fomichev.me>
> 
> Hm, odd. In NIPA we're getting:
> 
> TAP version 13
> 1..1
> # timeout set to 0
> # selftests: drivers/net/hw: devmem.py
> # TAP version 13
> # 1..5
> # ok 1 devmem.check_rx # SKIP marked as disruptive
> # ok 2 devmem.check_tx # SKIP marked as disruptive
> # ok 3 devmem.check_tx_chunks # SKIP marked as disruptive
> # ok 4 devmem.check_rx_hds # SKIP Test requires devmem support
> # ok 5 devmem.check_rx_large_niov # SKIP Test requires devmem support
> # # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:5 error:0
> ok 1 selftests: drivers/net/hw: devmem.py
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> 
> https://netdev.bots.linux.dev/logs/hwksft/BCM57508/results/755681/config
> driver: bnxt
> fw: 237.1.148.0
> 
> Any idea?

Poking around, it looks like 231.1.167.0 and above should support
everything, so fw should be okay AFAICT.

Looks like the config is missing CONFIG_NET_DEVMEM and CONFIG_UDMABUF?

Sorry, took me a while... was certain it was a bug in my code.

Not the failure here, but wondering if this was on ARM led to seeing
that 16K hardcoded rx_page_size in run_rx_large_niov() may fail on ARM
with 64K pages because it will fail the IS_ALIGN(16K, 64K) check...

Best,
Bobby

Re: [PATCH net-next v6 3/3] selftests/net: devmem.py: add check_rx_large_niov

[Jakub Kicinski]

On Thu, 30 Jul 2026 14:39:37 -0700 Bobby Eshleman wrote:
> Poking around, it looks like 231.1.167.0 and above should support
> everything, so fw should be okay AFAICT.
> 
> Looks like the config is missing CONFIG_NET_DEVMEM and CONFIG_UDMABUF?

Ah, damn, you're right. I grepped for DEVMEM and didn't look closely on
a hit. Turns out there's a non-NET DEVMEM, too.

Could you send a patch to add the missing config options to 
tools/testing/selftests/drivers/net/hw/config ?

Can be separate or part of this series, doesn't matter.

> Sorry, took me a while... was certain it was a bug in my code.
> 
> Not the failure here, but wondering if this was on ARM led to seeing
> that 16K hardcoded rx_page_size in run_rx_large_niov() may fail on ARM
> with 64K pages because it will fail the IS_ALIGN(16K, 64K) check...

Ah, good thought. We've been meaning to get an ARM64 server for NIPA
(our current server supplier is out). If it's not too hard could be nice
to guard against that. But also not a huge deal for HW tests if they
fail instead of skipping.