419ef19dba
Makes it easier to keep drivers like mt76 in sync with newer versions Signed-off-by: Felix Fietkau <nbd@nbd.name> (cherry picked from commit 9508ca44eb577a13e795e0a6c5683689efc61475) (cherry picked from commit 478041997f068c87c6356108cf3dc3b667666dd5)
140 lines
4.5 KiB
Diff
140 lines
4.5 KiB
Diff
From: Yunsheng Lin <linyunsheng@huawei.com>
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Date: Fri, 13 Oct 2023 14:48:21 +0800
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Subject: [PATCH] page_pool: fragment API support for 32-bit arch with 64-bit
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DMA
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Currently page_pool_alloc_frag() is not supported in 32-bit
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arch with 64-bit DMA because of the overlap issue between
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pp_frag_count and dma_addr_upper in 'struct page' for those
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arches, which seems to be quite common, see [1], which means
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driver may need to handle it when using fragment API.
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It is assumed that the combination of the above arch with an
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address space >16TB does not exist, as all those arches have
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64b equivalent, it seems logical to use the 64b version for a
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system with a large address space. It is also assumed that dma
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address is page aligned when we are dma mapping a page aligned
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buffer, see [2].
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That means we're storing 12 bits of 0 at the lower end for a
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dma address, we can reuse those bits for the above arches to
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support 32b+12b, which is 16TB of memory.
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If we make a wrong assumption, a warning is emitted so that
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user can report to us.
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1. https://lore.kernel.org/all/20211117075652.58299-1-linyunsheng@huawei.com/
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2. https://lore.kernel.org/all/20230818145145.4b357c89@kernel.org/
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Tested-by: Alexander Lobakin <aleksander.lobakin@intel.com>
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Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
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CC: Lorenzo Bianconi <lorenzo@kernel.org>
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CC: Alexander Duyck <alexander.duyck@gmail.com>
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CC: Liang Chen <liangchen.linux@gmail.com>
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CC: Guillaume Tucker <guillaume.tucker@collabora.com>
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CC: Matthew Wilcox <willy@infradead.org>
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CC: Linux-MM <linux-mm@kvack.org>
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Link: https://lore.kernel.org/r/20231013064827.61135-2-linyunsheng@huawei.com
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Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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---
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--- a/include/linux/mm_types.h
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+++ b/include/linux/mm_types.h
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@@ -125,18 +125,7 @@ struct page {
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struct page_pool *pp;
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unsigned long _pp_mapping_pad;
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unsigned long dma_addr;
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- union {
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- /**
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- * dma_addr_upper: might require a 64-bit
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- * value on 32-bit architectures.
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- */
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- unsigned long dma_addr_upper;
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- /**
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- * For frag page support, not supported in
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- * 32-bit architectures with 64-bit DMA.
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- */
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- atomic_long_t pp_frag_count;
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- };
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+ atomic_long_t pp_frag_count;
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};
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struct { /* Tail pages of compound page */
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unsigned long compound_head; /* Bit zero is set */
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--- a/include/net/page_pool/helpers.h
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+++ b/include/net/page_pool/helpers.h
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@@ -197,7 +197,7 @@ static inline void page_pool_recycle_dir
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page_pool_put_full_page(pool, page, true);
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}
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-#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT \
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+#define PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA \
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(sizeof(dma_addr_t) > sizeof(unsigned long))
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/**
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@@ -211,17 +211,25 @@ static inline dma_addr_t page_pool_get_d
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{
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dma_addr_t ret = page->dma_addr;
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- if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
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- ret |= (dma_addr_t)page->dma_addr_upper << 16 << 16;
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+ if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA)
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+ ret <<= PAGE_SHIFT;
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return ret;
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}
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-static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
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+static inline bool page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
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{
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+ if (PAGE_POOL_32BIT_ARCH_WITH_64BIT_DMA) {
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+ page->dma_addr = addr >> PAGE_SHIFT;
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+
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+ /* We assume page alignment to shave off bottom bits,
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+ * if this "compression" doesn't work we need to drop.
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+ */
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+ return addr != (dma_addr_t)page->dma_addr << PAGE_SHIFT;
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+ }
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+
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page->dma_addr = addr;
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- if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
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- page->dma_addr_upper = upper_32_bits(addr);
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+ return false;
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}
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static inline bool page_pool_put(struct page_pool *pool)
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--- a/net/core/page_pool.c
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+++ b/net/core/page_pool.c
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@@ -211,10 +211,6 @@ static int page_pool_init(struct page_po
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*/
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}
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- if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT &&
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- pool->p.flags & PP_FLAG_PAGE_FRAG)
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- return -EINVAL;
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-
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#ifdef CONFIG_PAGE_POOL_STATS
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pool->recycle_stats = alloc_percpu(struct page_pool_recycle_stats);
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if (!pool->recycle_stats)
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@@ -363,12 +359,20 @@ static bool page_pool_dma_map(struct pag
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if (dma_mapping_error(pool->p.dev, dma))
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return false;
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- page_pool_set_dma_addr(page, dma);
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+ if (page_pool_set_dma_addr(page, dma))
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+ goto unmap_failed;
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if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
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page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
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return true;
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+
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+unmap_failed:
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+ WARN_ON_ONCE("unexpected DMA address, please report to netdev@");
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+ dma_unmap_page_attrs(pool->p.dev, dma,
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+ PAGE_SIZE << pool->p.order, pool->p.dma_dir,
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+ DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING);
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+ return false;
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}
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static void page_pool_set_pp_info(struct page_pool *pool,
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