Implement a memory provider that allocates dmabuf devmem in the form of net_iov.
The provider receives a reference to the struct netdev_dmabuf_binding via the pool->mp_priv pointer. The driver needs to set this pointer for the provider in the net_iov.
The provider obtains a reference on the netdev_dmabuf_binding which guarantees the binding and the underlying mapping remains alive until the provider is destroyed.
Usage of PP_FLAG_DMA_MAP is required for this memory provide such that the page_pool can provide the driver with the dma-addrs of the devmem.
Support for PP_FLAG_DMA_SYNC_DEV is omitted for simplicity & p.order != 0.
Signed-off-by: Willem de Bruijn willemb@google.com Signed-off-by: Kaiyuan Zhang kaiyuanz@google.com Signed-off-by: Mina Almasry almasrymina@google.com Reviewed-by: Pavel Begunkov asml.silence@gmail.com
---
v21: - Provide empty definitions of functions moved to page_pool_priv.h, so that the build still succeeds when CONFIG_PAGE_POOL is not set.
v20: - Moved queue pp_params field from fast path entries to slow path entries. - Moved page_pool_check_memory_provider() call to inside netdev_rx_queue_restart (Pavel). - Removed binding arg to page_pool_check_memory_provider() (Pavel). - Removed unnecessary includes from page_pool.c - Removed EXPORT_SYMBOL(page_pool_mem_providers) (Jakub) - Check pool->slow.queue instead of walking binding xarray (Pavel & Jakub).
v19: - Add PP_FLAG_ALLOW_UNREADABLE_NETMEM flag. It serves 2 purposes, (a) it guards drivers that don't support unreadable netmem (net_iov backed) from accidentally getting exposed to it, and (b) drivers that wish to create header pools can unset it for that pool to force readable netmem. - Add page_pool_check_memory_provider, which verifies that the driver has created a page_pool with the expected configuration. This is used to report to the user if the mp configuration succeeded, and also verify that the driver is doing the right thing. - Don't reset niov->dma_addr on allocation/free.
v17: - Use ASSERT_RTNL (Jakub)
v16: - Add DEBUG_NET_WARN_ON_ONCE(!rtnl_is_locked()), to catch cases if page_pool_init without rtnl_locking when the queue is provided. In this case, the queue configuration may be changed while we're initing the page_pool, which could be a race.
v13: - Return on warning (Pavel). - Fixed pool->recycle_stats not being freed on error (Pavel). - Applied reviewed-by from Pavel.
v11: - Rebase to not use the ops. (Christoph)
v8: - Use skb_frag_size instead of frag->bv_len to fix patch-by-patch build error
v6: - refactor new memory provider functions into net/core/devmem.c (Pavel)
v2: - Disable devmem for p.order != 0
v1: - static_branch check in page_is_page_pool_iov() (Willem & Paolo). - PP_DEVMEM -> PP_IOV (David). - Require PP_FLAG_DMA_MAP (Jakub).
build fixes
--- include/net/mp_dmabuf_devmem.h | 44 +++++++++++++++ include/net/page_pool/types.h | 16 +++++- net/core/devmem.c | 66 ++++++++++++++++++++++ net/core/netdev_rx_queue.c | 7 +++ net/core/page_pool.c | 100 ++++++++++++++++++++++++--------- net/core/page_pool_priv.h | 20 +++++++ net/core/page_pool_user.c | 25 +++++++++ 7 files changed, 250 insertions(+), 28 deletions(-) create mode 100644 include/net/mp_dmabuf_devmem.h
diff --git a/include/net/mp_dmabuf_devmem.h b/include/net/mp_dmabuf_devmem.h new file mode 100644 index 000000000000..300a2356eed0 --- /dev/null +++ b/include/net/mp_dmabuf_devmem.h @@ -0,0 +1,44 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Dmabuf device memory provider. + * + * Authors: Mina Almasry almasrymina@google.com + * + */ +#ifndef _NET_MP_DMABUF_DEVMEM_H +#define _NET_MP_DMABUF_DEVMEM_H + +#include <net/netmem.h> + +#if defined(CONFIG_DMA_SHARED_BUFFER) && defined(CONFIG_GENERIC_ALLOCATOR) +int mp_dmabuf_devmem_init(struct page_pool *pool); + +netmem_ref mp_dmabuf_devmem_alloc_netmems(struct page_pool *pool, gfp_t gfp); + +void mp_dmabuf_devmem_destroy(struct page_pool *pool); + +bool mp_dmabuf_devmem_release_page(struct page_pool *pool, netmem_ref netmem); +#else +static inline int mp_dmabuf_devmem_init(struct page_pool *pool) +{ + return -EOPNOTSUPP; +} + +static inline netmem_ref mp_dmabuf_devmem_alloc_netmems(struct page_pool *pool, + gfp_t gfp) +{ + return 0; +} + +static inline void mp_dmabuf_devmem_destroy(struct page_pool *pool) +{ +} + +static inline bool mp_dmabuf_devmem_release_page(struct page_pool *pool, + netmem_ref netmem) +{ + return false; +} +#endif + +#endif /* _NET_MP_DMABUF_DEVMEM_H */ diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h index 4afd6dd56351..1b4698710f25 100644 --- a/include/net/page_pool/types.h +++ b/include/net/page_pool/types.h @@ -20,8 +20,17 @@ * device driver responsibility */ #define PP_FLAG_SYSTEM_POOL BIT(2) /* Global system page_pool */ +#define PP_FLAG_ALLOW_UNREADABLE_NETMEM BIT(3) /* Allow unreadable (net_iov + * backed) netmem in this + * page_pool. Drivers setting + * this must be able to support + * unreadable netmem, where + * netmem_address() would return + * NULL. This flag should not be + * set for header page_pools. + */ #define PP_FLAG_ALL (PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV | \ - PP_FLAG_SYSTEM_POOL) + PP_FLAG_SYSTEM_POOL | PP_FLAG_ALLOW_UNREADABLE_NETMEM)
/* * Fast allocation side cache array/stack @@ -57,7 +66,9 @@ struct pp_alloc_cache { * @offset: DMA sync address offset for PP_FLAG_DMA_SYNC_DEV * @slow: params with slowpath access only (initialization and Netlink) * @netdev: netdev this pool will serve (leave as NULL if none or multiple) - * @flags: PP_FLAG_DMA_MAP, PP_FLAG_DMA_SYNC_DEV, PP_FLAG_SYSTEM_POOL + * @queue: struct netdev_rx_queue this page_pool is being created for. + * @flags: PP_FLAG_DMA_MAP, PP_FLAG_DMA_SYNC_DEV, PP_FLAG_SYSTEM_POOL, + * PP_FLAG_ALLOW_UNREADABLE_NETMEM. */ struct page_pool_params { struct_group_tagged(page_pool_params_fast, fast, @@ -72,6 +83,7 @@ struct page_pool_params { ); struct_group_tagged(page_pool_params_slow, slow, struct net_device *netdev; + struct netdev_rx_queue *queue; unsigned int flags; /* private: used by test code only */ void (*init_callback)(netmem_ref netmem, void *arg); diff --git a/net/core/devmem.c b/net/core/devmem.c index 8cc727bbd137..fb088ebb945a 100644 --- a/net/core/devmem.c +++ b/net/core/devmem.c @@ -17,6 +17,7 @@ #include <linux/genalloc.h> #include <linux/dma-buf.h> #include <net/devmem.h> +#include <net/mp_dmabuf_devmem.h> #include <net/netdev_queues.h>
#include "page_pool_priv.h" @@ -313,4 +314,69 @@ void dev_dmabuf_uninstall(struct net_device *dev) xa_erase(&binding->bound_rxqs, xa_idx); } } + +/*** "Dmabuf devmem memory provider" ***/ + +int mp_dmabuf_devmem_init(struct page_pool *pool) +{ + struct net_devmem_dmabuf_binding *binding = pool->mp_priv; + + if (!binding) + return -EINVAL; + + if (!pool->dma_map) + return -EOPNOTSUPP; + + if (pool->dma_sync) + return -EOPNOTSUPP; + + if (pool->p.order != 0) + return -E2BIG; + + net_devmem_dmabuf_binding_get(binding); + return 0; +} + +netmem_ref mp_dmabuf_devmem_alloc_netmems(struct page_pool *pool, gfp_t gfp) +{ + struct net_devmem_dmabuf_binding *binding = pool->mp_priv; + netmem_ref netmem; + struct net_iov *niov; + + niov = net_devmem_alloc_dmabuf(binding); + if (!niov) + return 0; + + netmem = net_iov_to_netmem(niov); + + page_pool_set_pp_info(pool, netmem); + + pool->pages_state_hold_cnt++; + trace_page_pool_state_hold(pool, netmem, pool->pages_state_hold_cnt); + return netmem; +} + +void mp_dmabuf_devmem_destroy(struct page_pool *pool) +{ + struct net_devmem_dmabuf_binding *binding = pool->mp_priv; + + net_devmem_dmabuf_binding_put(binding); +} + +bool mp_dmabuf_devmem_release_page(struct page_pool *pool, netmem_ref netmem) +{ + if (WARN_ON_ONCE(!netmem_is_net_iov(netmem))) + return false; + + if (WARN_ON_ONCE(atomic_long_read(netmem_get_pp_ref_count_ref(netmem)) != + 1)) + return false; + + page_pool_clear_pp_info(netmem); + + net_devmem_free_dmabuf(netmem_to_net_iov(netmem)); + + /* We don't want the page pool put_page()ing our net_iovs. */ + return false; +} #endif diff --git a/net/core/netdev_rx_queue.c b/net/core/netdev_rx_queue.c index da11720a5983..e217a5838c87 100644 --- a/net/core/netdev_rx_queue.c +++ b/net/core/netdev_rx_queue.c @@ -4,8 +4,11 @@ #include <net/netdev_queues.h> #include <net/netdev_rx_queue.h>
+#include "page_pool_priv.h" + int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx) { + struct netdev_rx_queue *rxq = __netif_get_rx_queue(dev, rxq_idx); void *new_mem, *old_mem; int err;
@@ -31,6 +34,10 @@ int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx) if (err) goto err_free_old_mem;
+ err = page_pool_check_memory_provider(dev, rxq); + if (err) + goto err_free_new_queue_mem; + err = dev->queue_mgmt_ops->ndo_queue_stop(dev, old_mem, rxq_idx); if (err) goto err_free_new_queue_mem; diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 13277f05aebd..267c06dadf4a 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -13,6 +13,8 @@
#include <net/page_pool/helpers.h> #include <net/xdp.h> +#include <net/netdev_rx_queue.h> +#include <net/mp_dmabuf_devmem.h>
#include <linux/dma-direction.h> #include <linux/dma-mapping.h> @@ -190,6 +192,7 @@ static int page_pool_init(struct page_pool *pool, int cpuid) { unsigned int ring_qsize = 1024; /* Default */ + int err;
page_pool_struct_check();
@@ -271,7 +274,36 @@ static int page_pool_init(struct page_pool *pool, if (pool->dma_map) get_device(pool->p.dev);
+ if (pool->slow.queue && + pool->slow.flags & PP_FLAG_ALLOW_UNREADABLE_NETMEM) { + /* We rely on rtnl_lock()ing to make sure netdev_rx_queue + * configuration doesn't change while we're initializing the + * page_pool. + */ + ASSERT_RTNL(); + pool->mp_priv = pool->slow.queue->mp_params.mp_priv; + } + + if (pool->mp_priv) { + err = mp_dmabuf_devmem_init(pool); + if (err) { + pr_warn("%s() mem-provider init failed %d\n", __func__, + err); + goto free_ptr_ring; + } + + static_branch_inc(&page_pool_mem_providers); + } + return 0; + +free_ptr_ring: + ptr_ring_cleanup(&pool->ring, NULL); +#ifdef CONFIG_PAGE_POOL_STATS + if (!pool->system) + free_percpu(pool->recycle_stats); +#endif + return err; }
static void page_pool_uninit(struct page_pool *pool) @@ -455,28 +487,6 @@ static bool page_pool_dma_map(struct page_pool *pool, netmem_ref netmem) return false; }
-static void page_pool_set_pp_info(struct page_pool *pool, netmem_ref netmem) -{ - netmem_set_pp(netmem, pool); - netmem_or_pp_magic(netmem, PP_SIGNATURE); - - /* Ensuring all pages have been split into one fragment initially: - * page_pool_set_pp_info() is only called once for every page when it - * is allocated from the page allocator and page_pool_fragment_page() - * is dirtying the same cache line as the page->pp_magic above, so - * the overhead is negligible. - */ - page_pool_fragment_netmem(netmem, 1); - if (pool->has_init_callback) - pool->slow.init_callback(netmem, pool->slow.init_arg); -} - -static void page_pool_clear_pp_info(netmem_ref netmem) -{ - netmem_clear_pp_magic(netmem); - netmem_set_pp(netmem, NULL); -} - static struct page *__page_pool_alloc_page_order(struct page_pool *pool, gfp_t gfp) { @@ -572,7 +582,10 @@ netmem_ref page_pool_alloc_netmem(struct page_pool *pool, gfp_t gfp) return netmem;
/* Slow-path: cache empty, do real allocation */ - netmem = __page_pool_alloc_pages_slow(pool, gfp); + if (static_branch_unlikely(&page_pool_mem_providers) && pool->mp_priv) + netmem = mp_dmabuf_devmem_alloc_netmems(pool, gfp); + else + netmem = __page_pool_alloc_pages_slow(pool, gfp); return netmem; } EXPORT_SYMBOL(page_pool_alloc_netmem); @@ -608,6 +621,28 @@ s32 page_pool_inflight(const struct page_pool *pool, bool strict) return inflight; }
+void page_pool_set_pp_info(struct page_pool *pool, netmem_ref netmem) +{ + netmem_set_pp(netmem, pool); + netmem_or_pp_magic(netmem, PP_SIGNATURE); + + /* Ensuring all pages have been split into one fragment initially: + * page_pool_set_pp_info() is only called once for every page when it + * is allocated from the page allocator and page_pool_fragment_page() + * is dirtying the same cache line as the page->pp_magic above, so + * the overhead is negligible. + */ + page_pool_fragment_netmem(netmem, 1); + if (pool->has_init_callback) + pool->slow.init_callback(netmem, pool->slow.init_arg); +} + +void page_pool_clear_pp_info(netmem_ref netmem) +{ + netmem_clear_pp_magic(netmem); + netmem_set_pp(netmem, NULL); +} + static __always_inline void __page_pool_release_page_dma(struct page_pool *pool, netmem_ref netmem) { @@ -636,8 +671,13 @@ static __always_inline void __page_pool_release_page_dma(struct page_pool *pool, void page_pool_return_page(struct page_pool *pool, netmem_ref netmem) { int count; + bool put;
- __page_pool_release_page_dma(pool, netmem); + put = true; + if (static_branch_unlikely(&page_pool_mem_providers) && pool->mp_priv) + put = mp_dmabuf_devmem_release_page(pool, netmem); + else + __page_pool_release_page_dma(pool, netmem);
/* This may be the last page returned, releasing the pool, so * it is not safe to reference pool afterwards. @@ -645,8 +685,10 @@ void page_pool_return_page(struct page_pool *pool, netmem_ref netmem) count = atomic_inc_return_relaxed(&pool->pages_state_release_cnt); trace_page_pool_state_release(pool, netmem, count);
- page_pool_clear_pp_info(netmem); - put_page(netmem_to_page(netmem)); + if (put) { + page_pool_clear_pp_info(netmem); + put_page(netmem_to_page(netmem)); + } /* An optimization would be to call __free_pages(page, pool->p.order) * knowing page is not part of page-cache (thus avoiding a * __page_cache_release() call). @@ -965,6 +1007,12 @@ static void __page_pool_destroy(struct page_pool *pool)
page_pool_unlist(pool); page_pool_uninit(pool); + + if (pool->mp_priv) { + mp_dmabuf_devmem_destroy(pool); + static_branch_dec(&page_pool_mem_providers); + } + kfree(pool); }
diff --git a/net/core/page_pool_priv.h b/net/core/page_pool_priv.h index 2142caeddb7c..f90171dc477c 100644 --- a/net/core/page_pool_priv.h +++ b/net/core/page_pool_priv.h @@ -35,4 +35,24 @@ static inline bool page_pool_set_dma_addr(struct page *page, dma_addr_t addr) return page_pool_set_dma_addr_netmem(page_to_netmem(page), addr); }
+#if defined(CONFIG_PAGE_POOL) +void page_pool_set_pp_info(struct page_pool *pool, netmem_ref netmem); +void page_pool_clear_pp_info(netmem_ref netmem); +int page_pool_check_memory_provider(struct net_device *dev, + struct netdev_rx_queue *rxq); +#else +static inline void page_pool_set_pp_info(struct page_pool *pool, + netmem_ref netmem) +{ +} +static inline void page_pool_clear_pp_info(netmem_ref netmem) +{ +} +static inline int page_pool_check_memory_provider(struct net_device *dev, + struct netdev_rx_queue *rxq) +{ + return 0; +} +#endif + #endif diff --git a/net/core/page_pool_user.c b/net/core/page_pool_user.c index 3a3277ba167b..9b69066cc07e 100644 --- a/net/core/page_pool_user.c +++ b/net/core/page_pool_user.c @@ -7,6 +7,7 @@ #include <net/page_pool/types.h> #include <net/page_pool/helpers.h> #include <net/sock.h> +#include <net/netdev_rx_queue.h>
#include "page_pool_priv.h" #include "netdev-genl-gen.h" @@ -344,6 +345,30 @@ void page_pool_unlist(struct page_pool *pool) mutex_unlock(&page_pools_lock); }
+int page_pool_check_memory_provider(struct net_device *dev, + struct netdev_rx_queue *rxq) +{ + struct net_devmem_dmabuf_binding *binding = rxq->mp_params.mp_priv; + struct page_pool *pool; + struct hlist_node *n; + + if (!binding) + return 0; + + mutex_lock(&page_pools_lock); + hlist_for_each_entry_safe(pool, n, &dev->page_pools, user.list) { + if (pool->mp_priv != binding) + continue; + + if (pool->slow.queue == rxq) { + mutex_unlock(&page_pools_lock); + return 0; + } + } + mutex_unlock(&page_pools_lock); + return -ENODATA; +} + static void page_pool_unreg_netdev_wipe(struct net_device *netdev) { struct page_pool *pool;