linux/include/net/page_pool, branch v6.16

eth: bnxt: add support rx side device memory TCP

2025-04-17T01:17:57Z

Currently, bnxt_en driver satisfies the requirements of the Device memory TCP, which is HDS. So, it implements rx-side Device memory TCP for bnxt_en driver. It requires only converting the page API to netmem API. `struct page` of agg rings are changed to `netmem_ref netmem` and corresponding functions are changed to a variant of netmem API. It also passes PP_FLAG_ALLOW_UNREADABLE_NETMEM flag to a parameter of page_pool. The netmem will be activated only when a user requests devmem TCP. When netmem is activated, received data is unreadable and netmem is disabled, received data is readable. But drivers don't need to handle both cases because netmem core API will handle it properly. So, using proper netmem API is enough for drivers. Device memory TCP can be tested with tools/testing/selftests/drivers/net/hw/ncdevmem. This is tested with BCM57504-N425G and firmware version 232.0.155.8/pkg 232.1.132.8. Reviewed-by: Mina Almasry Tested-by: David Wei Signed-off-by: Taehee Yoo Link: https://patch.msgid.link/20250415052458.1260575-1-ap420073@gmail.com Signed-off-by: Jakub Kicinski

page_pool: Track DMA-mapped pages and unmap them when destroying the pool

2025-04-14T23:30:29Z

When enabling DMA mapping in page_pool, pages are kept DMA mapped until they are released from the pool, to avoid the overhead of re-mapping the pages every time they are used. This causes resource leaks and/or crashes when there are pages still outstanding while the device is torn down, because page_pool will attempt an unmap through a non-existent DMA device on the subsequent page return. To fix this, implement a simple tracking of outstanding DMA-mapped pages in page pool using an xarray. This was first suggested by Mina[0], and turns out to be fairly straight forward: We simply store pointers to pages directly in the xarray with xa_alloc() when they are first DMA mapped, and remove them from the array on unmap. Then, when a page pool is torn down, it can simply walk the xarray and unmap all pages still present there before returning, which also allows us to get rid of the get/put_device() calls in page_pool. Using xa_cmpxchg(), no additional synchronisation is needed, as a page will only ever be unmapped once. To avoid having to walk the entire xarray on unmap to find the page reference, we stash the ID assigned by xa_alloc() into the page structure itself, using the upper bits of the pp_magic field. This requires a couple of defines to avoid conflicting with the POINTER_POISON_DELTA define, but this is all evaluated at compile-time, so does not affect run-time performance. The bitmap calculations in this patch gives the following number of bits for different architectures: - 23 bits on 32-bit architectures - 21 bits on PPC64 (because of the definition of ILLEGAL_POINTER_VALUE) - 32 bits on other 64-bit architectures Stashing a value into the unused bits of pp_magic does have the effect that it can make the value stored there lie outside the unmappable range (as governed by the mmap_min_addr sysctl), for architectures that don't define ILLEGAL_POINTER_VALUE. This means that if one of the pointers that is aliased to the pp_magic field (such as page->lru.next) is dereferenced while the page is owned by page_pool, that could lead to a dereference into userspace, which is a security concern. The risk of this is mitigated by the fact that (a) we always clear pp_magic before releasing a page from page_pool, and (b) this would need a use-after-free bug for struct page, which can have many other risks since page->lru.next is used as a generic list pointer in multiple places in the kernel. As such, with this patch we take the position that this risk is negligible in practice. For more discussion, see[1]. Since all the tracking added in this patch is performed on DMA map/unmap, no additional code is needed in the fast path, meaning the performance overhead of this tracking is negligible there. A micro-benchmark shows that the total overhead of the tracking itself is about 400 ns (39 cycles(tsc) 395.218 ns; sum for both map and unmap[2]). Since this cost is only paid on DMA map and unmap, it seems like an acceptable cost to fix the late unmap issue. Further optimisation can narrow the cases where this cost is paid (for instance by eliding the tracking when DMA map/unmap is a no-op). The extra memory needed to track the pages is neatly encapsulated inside xarray, which uses the 'struct xa_node' structure to track items. This structure is 576 bytes long, with slots for 64 items, meaning that a full node occurs only 9 bytes of overhead per slot it tracks (in practice, it probably won't be this efficient, but in any case it should be an acceptable overhead). [0] https://lore.kernel.org/all/CAHS8izPg7B5DwKfSuzz-iOop_YRbk3Sd6Y4rX7KBG9DcVJcyWg@mail.gmail.com/ [1] https://lore.kernel.org/r/20250320023202.GA25514@openwall.com [2] https://lore.kernel.org/r/ae07144c-9295-4c9d-a400-153bb689fe9e@huawei.com Reported-by: Yonglong Liu Closes: https://lore.kernel.org/r/8743264a-9700-4227-a556-5f931c720211@huawei.com Fixes: ff7d6b27f894 ("page_pool: refurbish version of page_pool code") Suggested-by: Mina Almasry Reviewed-by: Mina Almasry Reviewed-by: Jesper Dangaard Brouer Tested-by: Jesper Dangaard Brouer Tested-by: Qiuling Ren Tested-by: Yuying Ma Tested-by: Yonglong Liu Acked-by: Jesper Dangaard Brouer Signed-off-by: Toke Høiland-Jørgensen Link: https://patch.msgid.link/20250409-page-pool-track-dma-v9-2-6a9ef2e0cba8@redhat.com Signed-off-by: Jakub Kicinski

net: move mp dev config validation to __net_mp_open_rxq()

2025-04-04T14:35:38Z

devmem code performs a number of safety checks to avoid having to reimplement all of them in the drivers. Move those to __net_mp_open_rxq() and reuse that function for binding to make sure that io_uring ZC also benefits from them. While at it rename the queue ID variable to rxq_idx in __net_mp_open_rxq(), we touch most of the relevant lines. The XArray insertion is reordered after the netdev_rx_queue_restart() call, otherwise we'd need to duplicate the queue index check or risk inserting an invalid pointer. The XArray allocation failures should be extremely rare. Reviewed-by: Mina Almasry Acked-by: Stanislav Fomichev Fixes: 6e18ed929d3b ("net: add helpers for setting a memory provider on an rx queue") Link: https://patch.msgid.link/20250403013405.2827250-2-kuba@kernel.org Signed-off-by: Jakub Kicinski

net: add helpers for setting a memory provider on an rx queue

2025-02-07T00:27:31Z

Add helpers that properly prep or remove a memory provider for an rx queue then restart the queue. Reviewed-by: Jakub Kicinski Signed-off-by: Pavel Begunkov Signed-off-by: David Wei Link: https://patch.msgid.link/20250204215622.695511-11-dw@davidwei.uk Signed-off-by: Jakub Kicinski

net: page_pool: add memory provider helpers

2025-02-07T00:27:31Z

Add helpers for memory providers to interact with page pools. net_mp_niov_{set,clear}_page_pool() serve to [dis]associate a net_iov with a page pool. If used, the memory provider is responsible to match "set" calls with "clear" once a net_iov is not going to be used by a page pool anymore, changing a page pool, etc. Acked-by: Jakub Kicinski Signed-off-by: Pavel Begunkov Signed-off-by: David Wei Link: https://patch.msgid.link/20250204215622.695511-10-dw@davidwei.uk Signed-off-by: Jakub Kicinski

net: page_pool: add a mp hook to unregister_netdevice*

2025-02-07T00:27:31Z

Devmem TCP needs a hook in unregister_netdevice_many_notify() to upkeep the set tracking queues it's bound to, i.e. ->bound_rxqs. Instead of devmem sticking directly out of the genetic path, add a mp function. Reviewed-by: Jakub Kicinski Reviewed-by: Mina Almasry Signed-off-by: Pavel Begunkov Signed-off-by: David Wei Link: https://patch.msgid.link/20250204215622.695511-8-dw@davidwei.uk Signed-off-by: Jakub Kicinski

net: page_pool: add callback for mp info printing

2025-02-07T00:27:31Z

Add a mandatory callback that prints information about the memory provider to netlink. Reviewed-by: Jakub Kicinski Signed-off-by: Pavel Begunkov Signed-off-by: David Wei Link: https://patch.msgid.link/20250204215622.695511-7-dw@davidwei.uk Signed-off-by: Jakub Kicinski

net: page_pool: create hooks for custom memory providers

2025-02-07T00:27:30Z

A spin off from the original page pool memory providers patch by Jakub, which allows extending page pools with custom allocators. One of such providers is devmem TCP, and the other is io_uring zerocopy added in following patches. Link: https://lore.kernel.org/netdev/20230707183935.997267-7-kuba@kernel.org/ Co-developed-by: Jakub Kicinski # initial mp proposal Signed-off-by: Pavel Begunkov Signed-off-by: David Wei Link: https://patch.msgid.link/20250204215622.695511-5-dw@davidwei.uk Signed-off-by: Jakub Kicinski

net: page_pool: don't try to stash the napi id

2025-01-27T22:37:41Z

Page ppol tried to cache the NAPI ID in page pool info to avoid having a dependency on the life cycle of the NAPI instance. Since commit under Fixes the NAPI ID is not populated until napi_enable() and there's a good chance that page pool is created before NAPI gets enabled. Protect the NAPI pointer with the existing page pool mutex, the reading path already holds it. napi_id itself we need to READ_ONCE(), it's protected by netdev_lock() which are not holding in page pool. Before this patch napi IDs were missing for mlx5: # ./cli.py --spec netlink/specs/netdev.yaml --dump page-pool-get [{'id': 144, 'ifindex': 2, 'inflight': 3072, 'inflight-mem': 12582912}, {'id': 143, 'ifindex': 2, 'inflight': 5568, 'inflight-mem': 22806528}, {'id': 142, 'ifindex': 2, 'inflight': 5120, 'inflight-mem': 20971520}, {'id': 141, 'ifindex': 2, 'inflight': 4992, 'inflight-mem': 20447232}, ... After: [{'id': 144, 'ifindex': 2, 'inflight': 3072, 'inflight-mem': 12582912, 'napi-id': 565}, {'id': 143, 'ifindex': 2, 'inflight': 4224, 'inflight-mem': 17301504, 'napi-id': 525}, {'id': 142, 'ifindex': 2, 'inflight': 4288, 'inflight-mem': 17563648, 'napi-id': 524}, ... Fixes: 86e25f40aa1e ("net: napi: Add napi_config") Reviewed-by: Mina Almasry Reviewed-by: Toke Høiland-Jørgensen Link: https://patch.msgid.link/20250123231620.1086401-1-kuba@kernel.org Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2025-01-16T18:34:59Z

Cross-merge networking fixes after downstream PR (net-6.13-rc8). Conflicts: drivers/net/ethernet/realtek/r8169_main.c 1f691a1fc4be ("r8169: remove redundant hwmon support") 152d00a91396 ("r8169: simplify setting hwmon attribute visibility") https://lore.kernel.org/20250115122152.760b4e8d@canb.auug.org.au Adjacent changes: drivers/net/ethernet/broadcom/bnxt/bnxt.c 152f4da05aee ("bnxt_en: add support for rx-copybreak ethtool command") f0aa6a37a3db ("eth: bnxt: always recalculate features after XDP clearing, fix null-deref") drivers/net/ethernet/intel/ice/ice_type.h 50327223a8bb ("ice: add lock to protect low latency interface") dc26548d729e ("ice: Fix quad registers read on E825") Signed-off-by: Jakub Kicinski