This is a note to let you know that I've just added the patch titled
x86/swiotlb: Enable swiotlb for > 4GiG RAM on 32-bit kernels
to the 4.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-swiotlb-enable-swiotlb-for-4gig-ram-on-32-bit-kernels.patch
and it can be found in the queue-4.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 485734f3fc77c1eb77ffe138c027b9a4bf0178f3 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@xxxxxx>
Date: Sun, 14 Oct 2018 09:52:08 +0200
Subject: x86/swiotlb: Enable swiotlb for > 4GiG RAM on 32-bit kernels
From: Christoph Hellwig <hch@xxxxxx>
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@xxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Matthew Whitehead <tedheadster@xxxxxxxxx>
Cc: konrad.wilk@xxxxxxxxxx
Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20181014075208.2715-1-hch@xxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/pci-swiotlb.c | 2 --
1 file changed, 2 deletions(-)
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -42,10 +42,8 @@ IOMMU_INIT_FINISH(pci_swiotlb_detect_ove
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
Patches currently in stable-queue which might be from hch@xxxxxx are
queue-4.18/block-don-t-deal-with-discard-limit-in-blkdev_issue_discard.patch
queue-4.18/x86-swiotlb-enable-swiotlb-for-4gig-ram-on-32-bit-kernels.patch
