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Fri, 22 Sep 2023 17:15:00 +0800 From: Yunsheng Lin To: , , CC: , , Yunsheng Lin , Lorenzo Bianconi , Alexander Duyck , Liang Chen , Alexander Lobakin , Guillaume Tucker , Matthew Wilcox , Linux-MM , Jesper Dangaard Brouer , Ilias Apalodimas , Eric Dumazet Subject: [PATCH net-next v10 1/6] page_pool: fragment API support for 32-bit arch with 64-bit DMA Date: Fri, 22 Sep 2023 17:11:33 +0800 Message-ID: <20230922091138.18014-2-linyunsheng@huawei.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20230922091138.18014-1-linyunsheng@huawei.com> References: <20230922091138.18014-1-linyunsheng@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.69.192.56] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500005.china.huawei.com (7.185.36.74) X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 412FE4002D X-Stat-Signature: m1g9edcpkaijmuhtd8pbda8pasykp38y X-HE-Tag: 1695374106-266635 X-HE-Meta: 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 rs19+tOp 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Currently page_pool_alloc_frag() is not supported in 32-bit arch with 64-bit DMA because of the overlap issue between pp_frag_count and dma_addr_upper in 'struct page' for those arches, which seems to be quite common, see [1], which means driver may need to handle it when using fragment API. It is assumed that the combination of the above arch with an address space >16TB does not exist, as all those arches have 64b equivalent, it seems logical to use the 64b version for a system with a large address space. It is also assumed that dma address is page aligned when we are dma mapping a page aligned buffer, see [2]. That means we're storing 12 bits of 0 at the lower end for a dma address, we can reuse those bits for the above arches to support 32b+12b, which is 16TB of memory. If we make a wrong assumption, a warning is emitted so that user can report to us. 1. https://lore.kernel.org/all/20211117075652.58299-1-linyunsheng@huawei.com/ 2. https://lore.kernel.org/all/20230818145145.4b357c89@kernel.org/ Signed-off-by: Jakub Kicinski Signed-off-by: Yunsheng Lin CC: Lorenzo Bianconi CC: Alexander Duyck CC: Liang Chen CC: Alexander Lobakin CC: Guillaume Tucker CC: Matthew Wilcox CC: Linux-MM Tested-by: Alexander Lobakin --- include/linux/mm_types.h | 13 +------------ include/net/page_pool/helpers.h | 20 ++++++++++++++------ net/core/page_pool.c | 14 +++++++++----- 3 files changed, 24 insertions(+), 23 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 36c5b43999e6..74b49c4c7a52 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -125,18 +125,7 @@ struct page { struct page_pool *pp; unsigned long _pp_mapping_pad; unsigned long dma_addr; - union { - /** - * dma_addr_upper: might require a 64-bit - * value on 32-bit architectures. - */ - unsigned long dma_addr_upper; - /** - * For frag page support, not supported in - * 32-bit architectures with 64-bit DMA. - */ - atomic_long_t pp_frag_count; - }; + atomic_long_t pp_frag_count; }; struct { /* Tail pages of compound page */ unsigned long compound_head; /* Bit zero is set */ diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h index 94231533a369..8e1c85de4995 100644 --- a/include/net/page_pool/helpers.h +++ b/include/net/page_pool/helpers.h @@ -197,7 +197,7 @@ static inline void page_pool_recycle_direct(struct page_pool *pool, page_pool_put_full_page(pool, page, true); } -#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT \ +#define PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA \ (sizeof(dma_addr_t) > sizeof(unsigned long)) /** @@ -211,17 +211,25 @@ static inline dma_addr_t page_pool_get_dma_addr(struct page *page) { dma_addr_t ret = page->dma_addr; - if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT) - ret |= (dma_addr_t)page->dma_addr_upper << 16 << 16; + if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA) + ret <<= PAGE_SHIFT; return ret; } -static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr) +static inline bool page_pool_set_dma_addr(struct page *page, dma_addr_t addr) { + if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA) { + page->dma_addr = addr >> PAGE_SHIFT; + + /* We assume page alignment to shave off bottom bits, + * if this "compression" doesn't work we need to drop. + */ + return addr != (dma_addr_t)page->dma_addr << PAGE_SHIFT; + } + page->dma_addr = addr; - if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT) - page->dma_addr_upper = upper_32_bits(addr); + return false; } static inline bool page_pool_put(struct page_pool *pool) diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 77cb75e63aca..8a9868ea5067 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -211,10 +211,6 @@ static int page_pool_init(struct page_pool *pool, */ } - if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT && - pool->p.flags & PP_FLAG_PAGE_FRAG) - return -EINVAL; - #ifdef CONFIG_PAGE_POOL_STATS pool->recycle_stats = alloc_percpu(struct page_pool_recycle_stats); if (!pool->recycle_stats) @@ -359,12 +355,20 @@ static bool page_pool_dma_map(struct page_pool *pool, struct page *page) if (dma_mapping_error(pool->p.dev, dma)) return false; - page_pool_set_dma_addr(page, dma); + if (page_pool_set_dma_addr(page, dma)) + goto unmap_failed; if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) page_pool_dma_sync_for_device(pool, page, pool->p.max_len); return true; + +unmap_failed: + WARN_ON_ONCE("unexpected DMA address, please report to netdev@"); + dma_unmap_page_attrs(pool->p.dev, dma, + PAGE_SIZE << pool->p.order, pool->p.dma_dir, + DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING); + return false; } static void page_pool_set_pp_info(struct page_pool *pool,