On 02/20, Mina Almasry wrote:

Drivers need to make sure not to pass netmem dma-addrs to the dma-mapping API in order to support netmem TX.

Add helpers and netmem_dma_*() helpers that enables special handling of netmem dma-addrs that drivers can use.

Document in netmem.rst what drivers need to do to support netmem TX.

Signed-off-by: Mina Almasry almasrymina@google.com

---

v4:

• New patch

---

.../networking/net_cachelines/net_device.rst | 1 + Documentation/networking/netdev-features.rst | 5 +++++ Documentation/networking/netmem.rst | 14 +++++++++++-- include/linux/netdevice.h | 2 ++ include/net/netmem.h | 20 +++++++++++++++++++ 5 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/Documentation/networking/net_cachelines/net_device.rst b/Documentation/networking/net_cachelines/net_device.rst index 15e31ece675f..e3043b033647 100644 --- a/Documentation/networking/net_cachelines/net_device.rst +++ b/Documentation/networking/net_cachelines/net_device.rst @@ -10,6 +10,7 @@ Type Name fastpath_tx_acce =================================== =========================== =================== =================== =================================================================================== unsigned_long:32 priv_flags read_mostly __dev_queue_xmit(tx) unsigned_long:1 lltx read_mostly HARD_TX_LOCK,HARD_TX_TRYLOCK,HARD_TX_UNLOCK(tx) +unsigned long:1 netmem_tx:1; read_mostly char name[16] struct netdev_name_node* name_node struct dev_ifalias* ifalias diff --git a/Documentation/networking/netdev-features.rst b/Documentation/networking/netdev-features.rst index 5014f7cc1398..02bd7536fc0c 100644 --- a/Documentation/networking/netdev-features.rst +++ b/Documentation/networking/netdev-features.rst @@ -188,3 +188,8 @@ Redundancy) frames from one port to another in hardware. This should be set for devices which duplicate outgoing HSR (High-availability Seamless Redundancy) or PRP (Parallel Redundancy Protocol) tags automatically frames in hardware.

+* netmem-tx

+This should be set for devices which support netmem TX. See +Documentation/networking/netmem.rst diff --git a/Documentation/networking/netmem.rst b/Documentation/networking/netmem.rst index 7de21ddb5412..43054d44c407 100644 --- a/Documentation/networking/netmem.rst +++ b/Documentation/networking/netmem.rst @@ -19,8 +19,8 @@ Benefits of Netmem :

• Simplified Development: Drivers interact with a consistent API, regardless of the underlying memory implementation.

-Driver Requirements

+Driver RX Requirements +======================

1. The driver must support page_pool.

@@ -77,3 +77,13 @@ Driver Requirements that purpose, but be mindful that some netmem types might have longer circulation times, such as when userspace holds a reference in zerocopy scenarios.

+Driver TX Requirements +======================

+1. Driver should use netmem_dma_unmap_page_attrs() in lieu of

• dma_unmap_page[_attrs](), and netmem_dma_unmap_addr_set() in lieu of
• dma_unmap_addr_set(). The netmem variants will handle netmems that should
• not be dma-unmapped by the driver, such as dma-buf netmems.

Not all drivers use dma_unmap_addr_xxx APIs (looking at mlx5). Might be worth mentioning that for the drivers managing the mappings differently, care might be taken to not unmap netmems?

+2. Driver should declare support by setting `netdev->netmem_tx = true` diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index fccc03cd2164..d8cfd5d69ddf 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1753,6 +1753,7 @@ enum netdev_reg_state {

• @lltx: device supports lockless Tx. Deprecated for real HW

• 	drivers. Mainly used by logical interfaces, such as
  

• 	bonding and tunnels
  

• • @netmem_tx: device support netmem_tx.
  • @name: This is the first field of the "visible" part of this structure

  • (i.e. as seen by users in the "Space.c" file).  It is the name
    

@@ -2061,6 +2062,7 @@ struct net_device { struct_group(priv_flags_fast, unsigned long priv_flags:32; unsigned long lltx:1;

• unsigned long		netmem_tx:1;
  

  ); const struct net_device_ops *netdev_ops; const struct header_ops *header_ops;

diff --git a/include/net/netmem.h b/include/net/netmem.h index a2148ffb203d..1fb39ad63290 100644 --- a/include/net/netmem.h +++ b/include/net/netmem.h @@ -8,6 +8,7 @@ #ifndef _NET_NETMEM_H #define _NET_NETMEM_H +#include <linux/dma-mapping.h> #include <linux/mm.h> #include <net/net_debug.h> @@ -267,4 +268,23 @@ static inline unsigned long netmem_get_dma_addr(netmem_ref netmem) void get_netmem(netmem_ref netmem); void put_netmem(netmem_ref netmem);

[..]

+#define netmem_dma_unmap_addr_set(NETMEM, PTR, ADDR_NAME, VAL) \

• do { \

• if (!netmem_is_net_iov(NETMEM))                  \
  

• 	dma_unmap_addr_set(PTR, ADDR_NAME, VAL); \
  

• else                                             \
  

• 	dma_unmap_addr_set(PTR, ADDR_NAME, 0);   \
  

• } while (0)

Any reason not do to static inline instaed?