blob: 79bc5c18b6737f7d28d1894b1d1cca2f151f5b4b [file] [log] [blame]
From 44bd3df8843ac1e4d1022ecc15df4ccbd2c1489c Mon Sep 17 00:00:00 2001
From: Mike Rapoport <rppt@linux.ibm.com>
Date: Wed, 4 Dec 2019 14:35:24 +0200
Subject: [PATCH] powerpc: Ensure that swiotlb buffer is allocated from low
memory
commit 8fabc623238e68b3ac63c0dd1657bf86c1fa33af upstream.
Some powerpc platforms (e.g. 85xx) limit DMA-able memory way below 4G.
If a system has more physical memory than this limit, the swiotlb
buffer is not addressable because it is allocated from memblock using
top-down mode.
Force memblock to bottom-up mode before calling swiotlb_init() to
ensure that the swiotlb buffer is DMA-able.
Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191204123524.22919-1-rppt@kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 2eda1ec36f55..99fcdf73f207 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -270,6 +270,14 @@ void __init mem_init(void)
BUILD_BUG_ON(MMU_PAGE_COUNT > 16);
#ifdef CONFIG_SWIOTLB
+ /*
+ * Some platforms (e.g. 85xx) limit DMA-able memory way below
+ * 4G. We force memblock to bottom-up mode to ensure that the
+ * memory allocated in swiotlb_init() is DMA-able.
+ * As it's the last memblock allocation, no need to reset it
+ * back to to-down.
+ */
+ memblock_set_bottom_up(true);
swiotlb_init(0);
#endif
--
2.7.4