[PATCH bpf-next v5 08/15] xsk: enable sharing of dma mappings
From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: 2020-08-28 08:27:53
Also in:
bpf
Subsystem:
networking [general], the rest, xdp sockets (af_xdp) · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Magnus Karlsson, Maciej Fijalkowski
Enable the sharing of dma mappings by moving them out from the buffer pool. Instead we put each dma mapped umem region in a list in the umem structure. If dma has already been mapped for this umem and device, it is not mapped again and the existing dma mappings are reused. Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com> Acked-by: Björn Töpel <redacted> --- include/net/xdp_sock.h | 1 + include/net/xsk_buff_pool.h | 13 ++++ net/xdp/xdp_umem.c | 1 + net/xdp/xsk_buff_pool.c | 183 ++++++++++++++++++++++++++++++++++---------- 4 files changed, 156 insertions(+), 42 deletions(-)
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 126d243..282aeba 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h@@ -30,6 +30,7 @@ struct xdp_umem { u8 flags; int id; bool zc; + struct list_head xsk_dma_list; }; struct xsk_map {
diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index 83f100c..356d0ac 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h@@ -28,10 +28,23 @@ struct xdp_buff_xsk { struct list_head free_list_node; }; +struct xsk_dma_map { + dma_addr_t *dma_pages; + struct device *dev; + struct net_device *netdev; + refcount_t users; + struct list_head list; /* Protected by the RTNL_LOCK */ + u32 dma_pages_cnt; + bool dma_need_sync; +}; + struct xsk_buff_pool { struct xsk_queue *fq; struct xsk_queue *cq; struct list_head free_list; + /* For performance reasons, each buff pool has its own array of dma_pages + * even when they are identical. + */ dma_addr_t *dma_pages; struct xdp_buff_xsk *heads; u64 chunk_mask;
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 77604c3..a7227b4 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c@@ -198,6 +198,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr) umem->user = NULL; umem->flags = mr->flags; + INIT_LIST_HEAD(&umem->xsk_dma_list); refcount_set(&umem->users, 1); err = xdp_umem_account_pages(umem);
diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
index c563874..547eb41 100644
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c@@ -104,6 +104,25 @@ void xp_set_rxq_info(struct xsk_buff_pool *pool, struct xdp_rxq_info *rxq) } EXPORT_SYMBOL(xp_set_rxq_info); +static void xp_disable_drv_zc(struct xsk_buff_pool *pool) +{ + struct netdev_bpf bpf; + int err; + + ASSERT_RTNL(); + + if (pool->umem->zc) { + bpf.command = XDP_SETUP_XSK_POOL; + bpf.xsk.pool = NULL; + bpf.xsk.queue_id = pool->queue_id; + + err = pool->netdev->netdev_ops->ndo_bpf(pool->netdev, &bpf); + + if (err) + WARN(1, "Failed to disable zero-copy!\n"); + } +} + int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *netdev, u16 queue_id, u16 flags) {
@@ -122,6 +141,8 @@ int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *netdev, if (xsk_get_pool_from_qid(netdev, queue_id)) return -EBUSY; + pool->netdev = netdev; + pool->queue_id = queue_id; err = xsk_reg_pool_at_qid(netdev, pool, queue_id); if (err) return err;
@@ -155,11 +176,15 @@ int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *netdev, if (err) goto err_unreg_pool; - pool->netdev = netdev; - pool->queue_id = queue_id; + if (!pool->dma_pages) { + WARN(1, "Driver did not DMA map zero-copy buffers"); + goto err_unreg_xsk; + } pool->umem->zc = true; return 0; +err_unreg_xsk: + xp_disable_drv_zc(pool); err_unreg_pool: if (!force_zc) err = 0; /* fallback to copy mode */
@@ -170,25 +195,10 @@ int xp_assign_dev(struct xsk_buff_pool *pool, struct net_device *netdev, void xp_clear_dev(struct xsk_buff_pool *pool) { - struct netdev_bpf bpf; - int err; - - ASSERT_RTNL(); - if (!pool->netdev) return; - if (pool->umem->zc) { - bpf.command = XDP_SETUP_XSK_POOL; - bpf.xsk.pool = NULL; - bpf.xsk.queue_id = pool->queue_id; - - err = pool->netdev->netdev_ops->ndo_bpf(pool->netdev, &bpf); - - if (err) - WARN(1, "Failed to disable zero-copy!\n"); - } - + xp_disable_drv_zc(pool); xsk_clear_pool_at_qid(pool->netdev, pool->queue_id); dev_put(pool->netdev); pool->netdev = NULL;
@@ -233,70 +243,159 @@ void xp_put_pool(struct xsk_buff_pool *pool) } } -void xp_dma_unmap(struct xsk_buff_pool *pool, unsigned long attrs) +static struct xsk_dma_map *xp_find_dma_map(struct xsk_buff_pool *pool) +{ + struct xsk_dma_map *dma_map; + + list_for_each_entry(dma_map, &pool->umem->xsk_dma_list, list) { + if (dma_map->netdev == pool->netdev) + return dma_map; + } + + return NULL; +} + +static struct xsk_dma_map *xp_create_dma_map(struct device *dev, struct net_device *netdev, + u32 nr_pages, struct xdp_umem *umem) +{ + struct xsk_dma_map *dma_map; + + dma_map = kzalloc(sizeof(*dma_map), GFP_KERNEL); + if (!dma_map) + return NULL; + + dma_map->dma_pages = kvcalloc(nr_pages, sizeof(*dma_map->dma_pages), GFP_KERNEL); + if (!dma_map) { + kfree(dma_map); + return NULL; + } + + dma_map->netdev = netdev; + dma_map->dev = dev; + dma_map->dma_need_sync = false; + dma_map->dma_pages_cnt = nr_pages; + refcount_set(&dma_map->users, 0); + list_add(&dma_map->list, &umem->xsk_dma_list); + return dma_map; +} + +static void xp_destroy_dma_map(struct xsk_dma_map *dma_map) +{ + list_del(&dma_map->list); + kvfree(dma_map->dma_pages); + kfree(dma_map); +} + +static void __xp_dma_unmap(struct xsk_dma_map *dma_map, unsigned long attrs) { dma_addr_t *dma; u32 i; - if (pool->dma_pages_cnt == 0) - return; - - for (i = 0; i < pool->dma_pages_cnt; i++) { - dma = &pool->dma_pages[i]; + for (i = 0; i < dma_map->dma_pages_cnt; i++) { + dma = &dma_map->dma_pages[i]; if (*dma) { - dma_unmap_page_attrs(pool->dev, *dma, PAGE_SIZE, + dma_unmap_page_attrs(dma_map->dev, *dma, PAGE_SIZE, DMA_BIDIRECTIONAL, attrs); *dma = 0; } } + xp_destroy_dma_map(dma_map); +} + +void xp_dma_unmap(struct xsk_buff_pool *pool, unsigned long attrs) +{ + struct xsk_dma_map *dma_map; + + if (pool->dma_pages_cnt == 0) + return; + + dma_map = xp_find_dma_map(pool); + if (!dma_map) { + WARN(1, "Could not find dma_map for device"); + return; + } + + if (!refcount_dec_and_test(&dma_map->users)) + return; + + __xp_dma_unmap(dma_map, attrs); kvfree(pool->dma_pages); pool->dma_pages_cnt = 0; pool->dev = NULL; } EXPORT_SYMBOL(xp_dma_unmap); -static void xp_check_dma_contiguity(struct xsk_buff_pool *pool) +static void xp_check_dma_contiguity(struct xsk_dma_map *dma_map) { u32 i; - for (i = 0; i < pool->dma_pages_cnt - 1; i++) { - if (pool->dma_pages[i] + PAGE_SIZE == pool->dma_pages[i + 1]) - pool->dma_pages[i] |= XSK_NEXT_PG_CONTIG_MASK; + for (i = 0; i < dma_map->dma_pages_cnt - 1; i++) { + if (dma_map->dma_pages[i] + PAGE_SIZE == dma_map->dma_pages[i + 1]) + dma_map->dma_pages[i] |= XSK_NEXT_PG_CONTIG_MASK; else - pool->dma_pages[i] &= ~XSK_NEXT_PG_CONTIG_MASK; + dma_map->dma_pages[i] &= ~XSK_NEXT_PG_CONTIG_MASK; } } +static int xp_init_dma_info(struct xsk_buff_pool *pool, struct xsk_dma_map *dma_map) +{ + pool->dma_pages = kvcalloc(dma_map->dma_pages_cnt, sizeof(*pool->dma_pages), GFP_KERNEL); + if (!pool->dma_pages) + return -ENOMEM; + + pool->dev = dma_map->dev; + pool->dma_pages_cnt = dma_map->dma_pages_cnt; + pool->dma_need_sync = dma_map->dma_need_sync; + refcount_inc(&dma_map->users); + memcpy(pool->dma_pages, dma_map->dma_pages, + pool->dma_pages_cnt * sizeof(*pool->dma_pages)); + + return 0; +} + int xp_dma_map(struct xsk_buff_pool *pool, struct device *dev, unsigned long attrs, struct page **pages, u32 nr_pages) { + struct xsk_dma_map *dma_map; dma_addr_t dma; + int err; u32 i; - pool->dma_pages = kvcalloc(nr_pages, sizeof(*pool->dma_pages), - GFP_KERNEL); - if (!pool->dma_pages) - return -ENOMEM; + dma_map = xp_find_dma_map(pool); + if (dma_map) { + err = xp_init_dma_info(pool, dma_map); + if (err) + return err; - pool->dev = dev; - pool->dma_pages_cnt = nr_pages; - pool->dma_need_sync = false; + return 0; + } - for (i = 0; i < pool->dma_pages_cnt; i++) { + dma_map = xp_create_dma_map(dev, pool->netdev, nr_pages, pool->umem); + if (!dma_map) + return -ENOMEM; + + for (i = 0; i < dma_map->dma_pages_cnt; i++) { dma = dma_map_page_attrs(dev, pages[i], 0, PAGE_SIZE, DMA_BIDIRECTIONAL, attrs); if (dma_mapping_error(dev, dma)) { - xp_dma_unmap(pool, attrs); + __xp_dma_unmap(dma_map, attrs); return -ENOMEM; } if (dma_need_sync(dev, dma)) - pool->dma_need_sync = true; - pool->dma_pages[i] = dma; + dma_map->dma_need_sync = true; + dma_map->dma_pages[i] = dma; } if (pool->unaligned) - xp_check_dma_contiguity(pool); + xp_check_dma_contiguity(dma_map); + + err = xp_init_dma_info(pool, dma_map); + if (err) { + __xp_dma_unmap(dma_map, attrs); + return err; + } + return 0; } EXPORT_SYMBOL(xp_dma_map);
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2.7.4