From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Rapoport Subject: [PATCH] powerpc: ensure that swiotlb buffer is allocated from low memory Date: Wed, 4 Dec 2019 14:35:24 +0200 Message-ID: <20191204123524.22919-1-rppt@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Mike Rapoport , Christian Zigotzky , Benjamin Herrenschmidt , Christoph Hellwig , Darren Stevens , mad skateman , Michael Ellerman , Nicolas Saenz Julienne , Paul Mackerras , Robin Murphy , Rob Herring List-Id: linux-arch.vger.kernel.org From: Mike Rapoport 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. Link: https://lkml.kernel.org/r/F1EBB706-73DF-430E-9020-C214EC8ED5DA@xenosoft.de Reported-by: Christian Zigotzky Signed-off-by: Mike Rapoport Cc: Benjamin Herrenschmidt Cc: Christoph Hellwig Cc: Darren Stevens Cc: mad skateman Cc: Michael Ellerman Cc: Nicolas Saenz Julienne Cc: Paul Mackerras Cc: Robin Murphy Cc: Rob Herring --- 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 be941d382c8d..14c2c53e3f9e 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -260,6 +260,14 @@ 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 -- 2.24.0 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Mike Rapoport Subject: [PATCH] powerpc: ensure that swiotlb buffer is allocated from low memory Date: Wed, 4 Dec 2019 14:35:24 +0200 Message-ID: <20191204123524.22919-1-rppt@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: linux-kernel@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Mike Rapoport , Christian Zigotzky , Benjamin Herrenschmidt , Christoph Hellwig , Darren Stevens , mad skateman , Michael Ellerman , Nicolas Saenz Julienne , Paul Mackerras , Robin Murphy , Rob Herring List-ID: Message-ID: <20191204123524.IavobDzHbkIGQa4NsRtmBGYviFts27NShLXHY4SoADA@z> From: Mike Rapoport 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. Link: https://lkml.kernel.org/r/F1EBB706-73DF-430E-9020-C214EC8ED5DA@xenosoft.de Reported-by: Christian Zigotzky Signed-off-by: Mike Rapoport Cc: Benjamin Herrenschmidt Cc: Christoph Hellwig Cc: Darren Stevens Cc: mad skateman Cc: Michael Ellerman Cc: Nicolas Saenz Julienne Cc: Paul Mackerras Cc: Robin Murphy Cc: Rob Herring --- 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 be941d382c8d..14c2c53e3f9e 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -260,6 +260,14 @@ 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 -- 2.24.0