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 Acked-by: Stanislav Fomichev sdf@fomichev.me
---
v8: - use spaces instead of tabs (Paolo)
v5: - Fix netmet TX documentation (Stan).
v4: - New patch --- .../networking/net_cachelines/net_device.rst | 1 + Documentation/networking/netdev-features.rst | 5 ++++ Documentation/networking/netmem.rst | 23 +++++++++++++++++-- include/linux/netdevice.h | 2 ++ include/net/netmem.h | 20 ++++++++++++++++ 5 files changed, 49 insertions(+), 2 deletions(-)
diff --git a/Documentation/networking/net_cachelines/net_device.rst b/Documentation/networking/net_cachelines/net_device.rst index ca8605eb82ffc..c69cc89c958e0 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 5014f7cc1398b..02bd7536fc0ca 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 7de21ddb54129..b63aded463370 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 +77,22 @@ 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. The Driver must not pass the netmem dma_addr to any of the dma-mapping APIs + directly. This is because netmem dma_addrs may come from a source like + dma-buf that is not compatible with the dma-mapping APIs. + + Helpers like netmem_dma_unmap_page_attrs() & netmem_dma_unmap_addr_set() + should be used in lieu of dma_unmap_page[_attrs](), dma_unmap_addr_set(). + The netmem variants will handle netmem dma_addrs correctly regardless of the + source, delegating to the dma-mapping APIs when appropriate. + + Not all dma-mapping APIs have netmem equivalents at the moment. If your + driver relies on a missing netmem API, feel free to add and propose to + netdev@, or reach out to the maintainers and/or almasrymina@google.com for + help adding the netmem API. + +2. Driver should declare support by setting `netdev->netmem_tx = true` diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 0321fd952f708..a661820a26c44 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1772,6 +1772,7 @@ 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 @@ -2087,6 +2088,7 @@ 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 ecb6b29c93f61..386164fb9c185 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>
@@ -276,4 +277,23 @@ 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) + +static inline void netmem_dma_unmap_page_attrs(struct device *dev, + dma_addr_t addr, size_t size, + enum dma_data_direction dir, + unsigned long attrs) +{ + if (!addr) + return; + + dma_unmap_page_attrs(dev, addr, size, dir, attrs); +} + #endif /* _NET_NETMEM_H */