page_pool: Revert "page_pool: disable dma mapping support..."

This reverts commit d00e60ee54b12de945b8493cf18c1ada9e422514.

As reported by Guillaume in [1]:
Enabling LPAE always enables CONFIG_ARCH_DMA_ADDR_T_64BIT
in 32-bit systems, which breaks the bootup proceess when a
ethernet driver is using page pool with PP_FLAG_DMA_MAP flag.
As we were hoping we had no active consumers for such system
when we removed the dma mapping support, and LPAE seems like
a common feature for 32 bits system, so revert it.

1. https://www.spinics.net/lists/netdev/msg779890.html

Fixes: d00e60ee54b1 ("page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Tested-by: "kernelci.org bot" <bot@kernelci.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index bb8c6f5f19bcaa41b3ad7ca343287c5908ebd331..c3a6e620960068cddb7818e1a39fac924bfd91fe 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -105,7 +105,18 @@ struct page {
                        struct page_pool *pp;
                        unsigned long _pp_mapping_pad;
                        unsigned long dma_addr;
-                       atomic_long_t pp_frag_count;
+                       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;
+                       };
                };
                struct {        /* slab, slob and slub */
                        union {

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index 3855f069627f454016dc64558d8accb9c5f31809..a4082406a0039611dd9a5d4633d1da8134d07c18 100644 (file)
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -216,14 +216,24 @@ 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        \
+               (sizeof(dma_addr_t) > sizeof(unsigned long))
+
 static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
 {
-       return page->dma_addr;
+       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;
+
+       return ret;
 }
 
 static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
 {
        page->dma_addr = addr;
+       if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
+               page->dma_addr_upper = upper_32_bits(addr);
 }
 
 static inline void page_pool_set_frag_count(struct page *page, long nr)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 9b60e4301a44fbf3b16c39396b14674bd827e900..1a6978427d6c86695d214fb75cca94d5240bb5aa 100644 (file)
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -49,12 +49,6 @@ static int page_pool_init(struct page_pool *pool,
         * which is the XDP_TX use-case.
         */
        if (pool->p.flags & PP_FLAG_DMA_MAP) {
-               /* DMA-mapping is not supported on 32-bit systems with
-                * 64-bit DMA mapping.
-                */
-               if (sizeof(dma_addr_t) > sizeof(unsigned long))
-                       return -EOPNOTSUPP;
-
                if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
                    (pool->p.dma_dir != DMA_BIDIRECTIONAL))
                        return -EINVAL;
@@ -75,6 +69,10 @@ 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;
+
        if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
                return -ENOMEM;