Patch "x86/swiotlb: Enable swiotlb for > 4GiG RAM on 32-bit kernels" has been added to the 4.18-stable tree

Patch "x86/swiotlb: Enable swiotlb for > 4GiG RAM on 32-bit kernels" has been added to the 4.18-stable tree

[gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r]

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-u79uwXL29TY76Z2rM5mHXA@public.gmane.org> know about it.


>From 485734f3fc77c1eb77ffe138c027b9a4bf0178f3 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
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-jcswGhMUV9g@public.gmane.org>

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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Signed-off-by: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Signed-off-by: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Tested-by: Matthew Whitehead <tedheadster-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Link: https://lkml.kernel.org/r/20181014075208.2715-1-hch-jcswGhMUV9g@public.gmane.org
Signed-off-by: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Signed-off-by: Greg Kroah-Hartman <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>

---
 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-jcswGhMUV9g@public.gmane.org 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