page_pool: disable sync for cpu for dmabuf memory provider

dmabuf dma-addresses should not be dma_sync'd for CPU/device. Typically
its the driver responsibility to dma_sync for CPU, but the driver should
not dma_sync for CPU if the netmem is actually coming from a dmabuf
memory provider.

The page_pool already exposes a helper for dma_sync_for_cpu:
page_pool_dma_sync_for_cpu. Upgrade this existing helper to handle
netmem, and have it skip dma_sync if the memory is from a dmabuf memory
provider. Drivers should migrate to using this helper when adding
support for netmem.

Also minimize the impact on the dma syncing performance for pages. Special
case the dma-sync path for pages to not go through the overhead checks
for dma-syncing and conversion to netmem.

Cc: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Signed-off-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20241211212033.1684197-5-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
index 95af7f0b029e4199cfe92619800d8511a48e1d08..e555921e52339a07643d76744d6609da5338360a 100644 (file)
--- a/include/net/page_pool/helpers.h
+++ b/include/net/page_pool/helpers.h
@@ -422,7 +422,21 @@ static inline dma_addr_t page_pool_get_dma_addr_netmem(netmem_ref netmem)
  */
 static inline dma_addr_t page_pool_get_dma_addr(const struct page *page)
 {
-       return page_pool_get_dma_addr_netmem(page_to_netmem((struct page *)page));
+       dma_addr_t ret = page->dma_addr;
+
+       if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA)
+               ret <<= PAGE_SHIFT;
+
+       return ret;
+}
+
+static inline void __page_pool_dma_sync_for_cpu(const struct page_pool *pool,
+                                               const dma_addr_t dma_addr,
+                                               u32 offset, u32 dma_sync_size)
+{
+       dma_sync_single_range_for_cpu(pool->p.dev, dma_addr,
+                                     offset + pool->p.offset, dma_sync_size,
+                                     page_pool_get_dma_dir(pool));
 }
 
 /**
@@ -441,10 +455,21 @@ static inline void page_pool_dma_sync_for_cpu(const struct page_pool *pool,
                                              const struct page *page,
                                              u32 offset, u32 dma_sync_size)
 {
-       dma_sync_single_range_for_cpu(pool->p.dev,
-                                     page_pool_get_dma_addr(page),
-                                     offset + pool->p.offset, dma_sync_size,
-                                     page_pool_get_dma_dir(pool));
+       __page_pool_dma_sync_for_cpu(pool, page_pool_get_dma_addr(page), offset,
+                                    dma_sync_size);
+}
+
+static inline void
+page_pool_dma_sync_netmem_for_cpu(const struct page_pool *pool,
+                                 const netmem_ref netmem, u32 offset,
+                                 u32 dma_sync_size)
+{
+       if (!pool->dma_sync_for_cpu)
+               return;
+
+       __page_pool_dma_sync_for_cpu(pool,
+                                    page_pool_get_dma_addr_netmem(netmem),
+                                    offset, dma_sync_size);
 }
 
 static inline bool page_pool_put(struct page_pool *pool)

diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index 3270c92841b49fff70b317b4f1a4152379560cd9..ed4cd114180ae8a416766bff8998cae250f734f3 100644 (file)
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -164,7 +164,8 @@ struct page_pool {
 
        bool has_init_callback:1;       /* slow::init_callback is set */
        bool dma_map:1;                 /* Perform DMA mapping */
-       bool dma_sync:1;                /* Perform DMA sync */
+       bool dma_sync:1;                /* Perform DMA sync for device */
+       bool dma_sync_for_cpu:1;        /* Perform DMA sync for cpu */
 #ifdef CONFIG_PAGE_POOL_STATS
        bool system:1;                  /* This is a global percpu pool */
 #endif

diff --git a/net/core/devmem.c b/net/core/devmem.c
index 3ebdeed2bf188d7c20420efc76edad421cb7f7c0..0b6ed7525b22ac559f153be99d2c983c4c6e307c 100644 (file)
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -335,6 +335,7 @@ int mp_dmabuf_devmem_init(struct page_pool *pool)
         * dma_sync_for_cpu/device. Force disable dma_sync.
         */
        pool->dma_sync = false;
+       pool->dma_sync_for_cpu = false;
 
        if (pool->p.order != 0)
                return -E2BIG;

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 275a7fd209d7a4e50dfec8f0494be23fc8829e74..e07ad73159550698e6fd291ffcaecf93255cbd1c 100644 (file)
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -201,6 +201,7 @@ static int page_pool_init(struct page_pool *pool,
        memcpy(&pool->slow, &params->slow, sizeof(pool->slow));
 
        pool->cpuid = cpuid;
+       pool->dma_sync_for_cpu = true;
 
        /* Validate only known flags were used */
        if (pool->slow.flags & ~PP_FLAG_ALL)