| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 33/84] powerpc: Ensure that swiotlb buffer is allocated from low memory | Date | Sat, 11 Jan 2020 10:50:10 +0100 |
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From: Mike Rapoport <rppt@linux.ibm.com>
[ Upstream commit 8fabc623238e68b3ac63c0dd1657bf86c1fa33af ]
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: Sasha Levin <sashal@kernel.org> --- arch/powerpc/mm/mem.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 04ccb274a620..9a6afd9f3f9b 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -344,6 +344,14 @@ 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 -- 2.20.1
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