Implement a memory provider that allocates dmabuf devmem page_pool_iovs.
Support of PP_FLAG_DMA_MAP and PP_FLAG_DMA_SYNC_DEV is omitted for simplicity.
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 page_pool_params.
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.
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
--- include/net/page_pool/helpers.h | 40 +++++++++++++++++ include/net/page_pool/types.h | 10 +++++ net/core/page_pool.c | 76 +++++++++++++++++++++++++++++++++ 3 files changed, 126 insertions(+)
diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h index 78cbb040af94..b93243c2a640 100644 --- a/include/net/page_pool/helpers.h +++ b/include/net/page_pool/helpers.h @@ -53,6 +53,7 @@ #define _NET_PAGE_POOL_HELPERS_H
#include <net/page_pool/types.h> +#include <net/net_debug.h>
#ifdef CONFIG_PAGE_POOL_STATS int page_pool_ethtool_stats_get_count(void); @@ -111,6 +112,45 @@ page_pool_iov_binding(const struct page_pool_iov *ppiov) return page_pool_iov_owner(ppiov)->binding; }
+static inline int page_pool_iov_refcount(const struct page_pool_iov *ppiov) +{ + return refcount_read(&ppiov->refcount); +} + +static inline void page_pool_iov_get_many(struct page_pool_iov *ppiov, + unsigned int count) +{ + refcount_add(count, &ppiov->refcount); +} + +void __page_pool_iov_free(struct page_pool_iov *ppiov); + +static inline void page_pool_iov_put_many(struct page_pool_iov *ppiov, + unsigned int count) +{ + if (!refcount_sub_and_test(count, &ppiov->refcount)) + return; + + __page_pool_iov_free(ppiov); +} + +/* page pool mm helpers */ + +static inline bool page_is_page_pool_iov(const struct page *page) +{ + return (unsigned long)page & PP_DEVMEM; +} + +static inline struct page_pool_iov *page_to_page_pool_iov(struct page *page) +{ + if (page_is_page_pool_iov(page)) + return (struct page_pool_iov *)((unsigned long)page & + ~PP_DEVMEM); + + DEBUG_NET_WARN_ON_ONCE(true); + return NULL; +} + /** * page_pool_dev_alloc_pages() - allocate a page. * @pool: pool from which to allocate diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h index 64386325d965..1e67f9466250 100644 --- a/include/net/page_pool/types.h +++ b/include/net/page_pool/types.h @@ -124,6 +124,7 @@ struct mem_provider;
enum pp_memory_provider_type { __PP_MP_NONE, /* Use system allocator directly */ + PP_MP_DMABUF_DEVMEM, /* dmabuf devmem provider */ };
struct pp_memory_provider_ops { @@ -133,8 +134,15 @@ struct pp_memory_provider_ops { bool (*release_page)(struct page_pool *pool, struct page *page); };
+extern const struct pp_memory_provider_ops dmabuf_devmem_ops; + /* page_pool_iov support */
+/* We overload the LSB of the struct page pointer to indicate whether it's + * a page or page_pool_iov. + */ +#define PP_DEVMEM 0x01UL + /* Owner of the dma-buf chunks inserted into the gen pool. Each scatterlist * entry from the dmabuf is inserted into the genpool as a chunk, and needs * this owner struct to keep track of some metadata necessary to create @@ -158,6 +166,8 @@ struct page_pool_iov { struct dmabuf_genpool_chunk_owner *owner;
refcount_t refcount; + + struct page_pool *pp; };
struct page_pool { diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 7ea1f4682479..138ddea0b28f 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -20,6 +20,7 @@ #include <linux/poison.h> #include <linux/ethtool.h> #include <linux/netdevice.h> +#include <linux/genalloc.h>
#include <trace/events/page_pool.h>
@@ -231,6 +232,9 @@ static int page_pool_init(struct page_pool *pool, switch (pool->p.memory_provider) { case __PP_MP_NONE: break; + case PP_MP_DMABUF_DEVMEM: + pool->mp_ops = &dmabuf_devmem_ops; + break; default: err = -EINVAL; goto free_ptr_ring; @@ -996,3 +1000,75 @@ void page_pool_update_nid(struct page_pool *pool, int new_nid) } } EXPORT_SYMBOL(page_pool_update_nid); + +void __page_pool_iov_free(struct page_pool_iov *ppiov) +{ + if (ppiov->pp->mp_ops != &dmabuf_devmem_ops) + return; + + netdev_free_devmem(ppiov); +} +EXPORT_SYMBOL_GPL(__page_pool_iov_free); + +/*** "Dmabuf devmem memory provider" ***/ + +static int mp_dmabuf_devmem_init(struct page_pool *pool) +{ + struct netdev_dmabuf_binding *binding = pool->mp_priv; + + if (!binding) + return -EINVAL; + + if (pool->p.flags & PP_FLAG_DMA_MAP || + pool->p.flags & PP_FLAG_DMA_SYNC_DEV) + return -EOPNOTSUPP; + + netdev_devmem_binding_get(binding); + return 0; +} + +static struct page *mp_dmabuf_devmem_alloc_pages(struct page_pool *pool, + gfp_t gfp) +{ + struct netdev_dmabuf_binding *binding = pool->mp_priv; + struct page_pool_iov *ppiov; + + ppiov = netdev_alloc_devmem(binding); + if (!ppiov) + return NULL; + + ppiov->pp = pool; + pool->pages_state_hold_cnt++; + trace_page_pool_state_hold(pool, (struct page *)ppiov, + pool->pages_state_hold_cnt); + return (struct page *)((unsigned long)ppiov | PP_DEVMEM); +} + +static void mp_dmabuf_devmem_destroy(struct page_pool *pool) +{ + struct netdev_dmabuf_binding *binding = pool->mp_priv; + + netdev_devmem_binding_put(binding); +} + +static bool mp_dmabuf_devmem_release_page(struct page_pool *pool, + struct page *page) +{ + struct page_pool_iov *ppiov; + + if (WARN_ON_ONCE(!page_is_page_pool_iov(page))) + return false; + + ppiov = page_to_page_pool_iov(page); + page_pool_iov_put_many(ppiov, 1); + /* We don't want the page pool put_page()ing our page_pool_iovs. */ + return false; +} + +const struct pp_memory_provider_ops dmabuf_devmem_ops = { + .init = mp_dmabuf_devmem_init, + .destroy = mp_dmabuf_devmem_destroy, + .alloc_pages = mp_dmabuf_devmem_alloc_pages, + .release_page = mp_dmabuf_devmem_release_page, +}; +EXPORT_SYMBOL(dmabuf_devmem_ops);