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authorChristoph Hellwig <hch@lst.de>2018-10-14 09:52:08 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-11-10 07:49:48 -0800
commit5581e4eed999140fe48d4aa5cbe7fbd90e5f18ca (patch)
tree7e2bde53b43e26c231f638c92796d779b0c722a3
parent022601efef9ee3b2b91f349e48fdd8d5131bf2ec (diff)
x86/swiotlb: Enable swiotlb for > 4GiG RAM on 32-bit kernels
commit 485734f3fc77c1eb77ffe138c027b9a4bf0178f3 upstream. We already build the swiotlb code for 32-bit kernels with PAE support, but the code to actually use swiotlb has only been enabled for 64-bit kernels for an unknown reason. Before Linux v4.18 we paper over this fact because the networking code, the SCSI layer and some random block drivers implemented their own bounce buffering scheme. [ mingo: Changelog fixes. ] Fixes: 21e07dba9fb1 ("scsi: reduce use of block bounce buffers") Fixes: ab74cfebafa3 ("net: remove the PCI_DMA_BUS_IS_PHYS check in illegal_highdma") Reported-by: Matthew Whitehead <tedheadster@gmail.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Matthew Whitehead <tedheadster@gmail.com> Cc: konrad.wilk@oracle.com Cc: iommu@lists.linux-foundation.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20181014075208.2715-1-hch@lst.de Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kernel/pci-swiotlb.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
index 661583662430..71c0b01d93b1 100644
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -42,10 +42,8 @@ IOMMU_INIT_FINISH(pci_swiotlb_detect_override,
int __init pci_swiotlb_detect_4gb(void)
{
/* don't initialize swiotlb if iommu=off (no_iommu=1) */
-#ifdef CONFIG_X86_64
if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
swiotlb = 1;
-#endif
/*
* If SME is active then swiotlb will be set to 1 so that bounce