Re: [Xen-devel] patch "[PATCH] xen/swiotlb: Use page alignment for early buffer allocation." failed to apply to 3.1-stable tree

["Taylor, Neal E" <Neal.Taylor@xxxxxx>]

Konrad,

This patch applies and compiles on 3.1.5 and 3.0.4. I'll test tomorrow.

Neal

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 8e964b9..5c8e445 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -166,7 +166,8 @@ retry:
        /*
         * Get IO TLB memory from any location.
         */
-       xen_io_tlb_start = alloc_bootmem(bytes);
+       xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
+
        if (!xen_io_tlb_start)
                panic("Cannot allocate SWIOTLB buffer");

-----Original Message-----
From: gregkh@xxxxxxx [mailto:gregkh@xxxxxxx] 
Sent: Thursday, December 15, 2011 3:14 PM
To: konrad.wilk@xxxxxxxxxx; Kalev, Leonid; Taylor, Neal E
Cc: stable@xxxxxxxxxxxxxxx
Subject: patch "[PATCH] xen/swiotlb: Use page alignment for early buffer 
allocation." failed to apply to 3.1-stable tree


The patch below does not apply to the 3.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 63a741757d15320a25ebf5778f8651cce2ed0611 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Thu, 15 Dec 2011 11:28:46 -0500
Subject: [PATCH] xen/swiotlb: Use page alignment for early buffer allocation.

This fixes an odd bug found on a Dell PowerEdge 1850/0RC130
(BIOS A05 01/09/2006) where all of the modules doing pci_set_dma_mask
would fail with:

ata_piix 0000:00:1f.1: enabling device (0005 -> 0007)
ata_piix 0000:00:1f.1: can't derive routing for PCI INT A
ata_piix 0000:00:1f.1: BMDMA: failed to set dma mask, falling back to PIO

The issue was the Xen-SWIOTLB was allocated such as that the end of
buffer was stradling a page (and also above 4GB). The fix was
spotted by Kalev Leonid  which was to piggyback on git commit
e79f86b2ef9c0a8c47225217c1018b7d3d90101c "swiotlb: Use page alignment
for early buffer allocation" which:

        We could call free_bootmem_late() if swiotlb is not used, and
        it will shrink to page alignment.

        So alloc them with page alignment at first, to avoid lose two pages

And doing that fixes the outstanding issue.

CC: stable@xxxxxxxxxx
Suggested-by: "Kalev, Leonid" <Leonid.Kalev@xxxxxx>
Reported-and-Tested-by: "Taylor, Neal E" <Neal.Taylor@xxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 8e964b9..284798a 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -166,7 +166,7 @@ retry:
        /*
         * Get IO TLB memory from any location.
         */
-       xen_io_tlb_start = alloc_bootmem(bytes);
+       xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
        if (!xen_io_tlb_start) {
                m = "Cannot allocate Xen-SWIOTLB buffer!\n";
                goto error;
@@ -179,7 +179,7 @@ retry:
                               bytes,
                               xen_io_tlb_nslabs);
        if (rc) {
-               free_bootmem(__pa(xen_io_tlb_start), bytes);
+               free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
                m = "Failed to get contiguous memory for DMA from Xen!\n"\
                    "You either: don't have the permissions, do not have"\
                    " enough free memory under 4GB, or the hypervisor memory"\


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