From: Mike Rapoport <rppt@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org,
Darren Stevens <darren@stevens-zone.net>,
Robin Murphy <robin.murphy@arm.com>,
Mike Rapoport <rppt@linux.ibm.com>,
linux-mm@kvack.org, iommu@lists.linux-foundation.org,
Rob Herring <robh+dt@kernel.org>,
Paul Mackerras <paulus@samba.org>,
mad skateman <madskateman@gmail.com>,
Christian Zigotzky <chzigotzky@xenosoft.de>,
linuxppc-dev@lists.ozlabs.org, Christoph Hellwig <hch@lst.de>,
Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Subject: [PATCH] powerpc: ensure that swiotlb buffer is allocated from low memory
Date: Wed, 4 Dec 2019 14:35:24 +0200 [thread overview]
Message-ID: <20191204123524.22919-1-rppt@kernel.org> (raw)
From: Mike Rapoport <rppt@linux.ibm.com>
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 <chzigotzky@xenosoft.de>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Darren Stevens <darren@stevens-zone.net>
Cc: mad skateman <madskateman@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Rob Herring <robh+dt@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 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
next reply other threads:[~2019-12-04 12:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-04 12:35 Mike Rapoport [this message]
2019-12-04 13:56 ` [PATCH] powerpc: ensure that swiotlb buffer is allocated from low memory Christoph Hellwig
2019-12-09 5:43 ` Michael Ellerman
2019-12-09 7:54 ` Mike Rapoport
2019-12-18 4:05 ` Michael Ellerman
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