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Date: Fri, 10 Jul 2020 16:16:36 +0200
From: Magnus Karlsson <magnus.karlsson@...el.com>
To: magnus.karlsson@...el.com, bjorn.topel@...el.com, ast@...nel.org,
daniel@...earbox.net, netdev@...r.kernel.org,
jonathan.lemon@...il.com, maximmi@...lanox.com
Cc: bpf@...r.kernel.org, jeffrey.t.kirsher@...el.com,
maciej.fijalkowski@...el.com, maciejromanfijalkowski@...il.com,
cristian.dumitrescu@...el.com
Subject: [PATCH bpf-next v2 08/14] xsk: enable sharing of dma mappings
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@...el.com>
---
include/net/xdp_sock.h | 1 +
include/net/xsk_buff_pool.h | 7 +++
net/xdp/xdp_umem.c | 1 +
net/xdp/xsk_buff_pool.c | 112 ++++++++++++++++++++++++++++++++++++--------
4 files changed, 102 insertions(+), 19 deletions(-)
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 6b99c80..2196f1e 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 eef8ca7..ce0a7c0 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -28,6 +28,13 @@ struct xdp_buff_xsk {
struct list_head free_list_node;
};
+struct xsk_dma_map {
+ dma_addr_t *dma_pages;
+ struct net_device *dev;
+ refcount_t users;
+ struct list_head list; /* Protected by the RTNL_LOCK */
+};
+
struct xsk_buff_pool {
struct xsk_queue *fq;
struct xsk_queue *cq;
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 372998d..cf27249 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -199,6 +199,7 @@ 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 9e50d2e..83c0d3c 100644
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -105,6 +105,25 @@ 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)
{
@@ -123,6 +142,8 @@ 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;
@@ -156,11 +177,15 @@ 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 */
@@ -171,25 +196,10 @@ 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;
@@ -234,14 +244,61 @@ void xp_put_pool(struct xsk_buff_pool *pool)
}
}
+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->dev == pool->netdev)
+ return dma_map;
+ }
+
+ return NULL;
+}
+
+static void xp_destroy_dma_map(struct xsk_dma_map *dma_map)
+{
+ list_del(&dma_map->list);
+ kfree(dma_map);
+}
+
+static void xp_put_dma_map(struct xsk_dma_map *dma_map)
+{
+ if (!refcount_dec_and_test(&dma_map->users))
+ return;
+
+ xp_destroy_dma_map(dma_map);
+}
+
+static struct xsk_dma_map *xp_create_dma_map(struct xsk_buff_pool *pool)
+{
+ struct xsk_dma_map *dma_map;
+
+ dma_map = kzalloc(sizeof(*dma_map), GFP_KERNEL);
+ if (!dma_map)
+ return NULL;
+
+ dma_map->dev = pool->netdev;
+ refcount_set(&dma_map->users, 1);
+ list_add(&dma_map->list, &pool->umem->xsk_dma_list);
+ return dma_map;
+}
+
void xp_dma_unmap(struct xsk_buff_pool *pool, unsigned long attrs)
{
+ struct xsk_dma_map *dma_map;
dma_addr_t *dma;
u32 i;
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;
+ }
+
for (i = 0; i < pool->dma_pages_cnt; i++) {
dma = &pool->dma_pages[i];
if (*dma) {
@@ -251,6 +308,7 @@ void xp_dma_unmap(struct xsk_buff_pool *pool, unsigned long attrs)
}
}
+ xp_put_dma_map(dma_map);
kvfree(pool->dma_pages);
pool->dma_pages_cnt = 0;
pool->dev = NULL;
@@ -314,14 +372,29 @@ static bool xp_check_cheap_dma(struct xsk_buff_pool *pool)
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;
u32 i;
+ dma_map = xp_find_dma_map(pool);
+ if (dma_map) {
+ pool->dma_pages = dma_map->dma_pages;
+ refcount_inc(&dma_map->users);
+ return 0;
+ }
+
+ dma_map = xp_create_dma_map(pool);
+ if (!dma_map)
+ return -ENOMEM;
+
pool->dma_pages = kvcalloc(nr_pages, sizeof(*pool->dma_pages),
GFP_KERNEL);
- if (!pool->dma_pages)
+ if (!pool->dma_pages) {
+ xp_destroy_dma_map(dma_map);
return -ENOMEM;
+ }
+ dma_map->dma_pages = pool->dma_pages;
pool->dev = dev;
pool->dma_pages_cnt = nr_pages;
@@ -330,6 +403,7 @@ int xp_dma_map(struct xsk_buff_pool *pool, struct device *dev,
DMA_BIDIRECTIONAL, attrs);
if (dma_mapping_error(dev, dma)) {
xp_dma_unmap(pool, attrs);
+ xp_destroy_dma_map(dma_map);
return -ENOMEM;
}
pool->dma_pages[i] = dma;
--
2.7.4
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