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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Donald Hunter , Jonathan Corbet , Andrew Lunn , Jeroen de Borst , Praveen Kaligineedi , Shailend Chand , Kuniyuki Iwashima , Willem de Bruijn , David Ahern , Neal Cardwell , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , Eugenio =?utf-8?B?UMOpcmV6?= , Stefan Hajnoczi , Stefano Garzarella , Shuah Khan , sdf@fomichev.me, asml.silence@gmail.com, dw@davidwei.uk, Jamal Hadi Salim , Victor Nogueira , Pedro Tammela , Samiullah Khawaja Subject: Re: [PATCH net-next v4 6/9] net: enable driver support for netmem TX Message-ID: References: <20250220020914.895431-1-almasrymina@google.com> <20250220020914.895431-7-almasrymina@google.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250220020914.895431-7-almasrymina@google.com> 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 > > --- > > 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 > #include > #include > > @@ -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?