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 d30a2e6e68b4..9f5b32163bda 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -282,6 +282,14 @@ 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