51 lines
1.8 KiB
Diff
51 lines
1.8 KiB
Diff
From: Christoph Hellwig <hch@lst.de>
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Date: Sun, 14 Oct 2018 09:52:08 +0200
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Subject: x86/swiotlb: Enable swiotlb for > 4GiG RAM on 32-bit kernels
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Origin: https://git.kernel.org/linus/485734f3fc77c1eb77ffe138c027b9a4bf0178f3
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Bug-Debian: https://bugs.debian.org/908924
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Bug: https://bugzilla.kernel.org/show_bug.cgi?id=200709
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We already build the swiotlb code for 32-bit kernels with PAE support,
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but the code to actually use swiotlb has only been enabled for 64-bit
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kernels for an unknown reason.
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Before Linux v4.18 we paper over this fact because the networking code,
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the SCSI layer and some random block drivers implemented their own
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bounce buffering scheme.
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[ mingo: Changelog fixes. ]
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Fixes: 21e07dba9fb1 ("scsi: reduce use of block bounce buffers")
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Fixes: ab74cfebafa3 ("net: remove the PCI_DMA_BUS_IS_PHYS check in illegal_highdma")
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Reported-by: Matthew Whitehead <tedheadster@gmail.com>
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Signed-off-by: Christoph Hellwig <hch@lst.de>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Tested-by: Matthew Whitehead <tedheadster@gmail.com>
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Cc: konrad.wilk@oracle.com
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Cc: iommu@lists.linux-foundation.org
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Cc: stable@vger.kernel.org
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Link: https://lkml.kernel.org/r/20181014075208.2715-1-hch@lst.de
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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---
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arch/x86/kernel/pci-swiotlb.c | 2 --
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1 file changed, 2 deletions(-)
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diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
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index 661583662430..71c0b01d93b1 100644
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--- a/arch/x86/kernel/pci-swiotlb.c
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+++ b/arch/x86/kernel/pci-swiotlb.c
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@@ -42,10 +42,8 @@ IOMMU_INIT_FINISH(pci_swiotlb_detect_override,
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int __init pci_swiotlb_detect_4gb(void)
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{
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/* don't initialize swiotlb if iommu=off (no_iommu=1) */
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-#ifdef CONFIG_X86_64
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if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
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swiotlb = 1;
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-#endif
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/*
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* If SME is active then swiotlb will be set to 1 so that bounce
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--
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2.19.1
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