[3.11.y.z extended stable] Patch "x86: Adjust irq remapping quirk for older revisions of 5500/5520 chipsets" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    x86: Adjust irq remapping quirk for older revisions of 5500/5520 chipsets

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From b5340cf2ec6c9c854db5de96295eb25620ddcf88 Mon Sep 17 00:00:00 2001
From: Neil Horman <nhorman at tuxdriver.com>
Date: Wed, 12 Mar 2014 14:44:33 -0400
Subject: x86: Adjust irq remapping quirk for older revisions of 5500/5520
 chipsets

commit 6f8a1b335fde143b7407036e2368d3cd6eb55674 upstream.

Commit 03bbcb2e7e2 (iommu/vt-d: add quirk for broken interrupt
remapping on 55XX chipsets) properly disables irq remapping on the
5500/5520 chipsets that don't correctly perform that feature.

However, when I wrote it, I followed the errata sheet linked in that
commit too closely, and explicitly tied the activation of the quirk to
revision 0x13 of the chip, under the assumption that earlier revisions
were not in the field.  Recently a system was reported to be suffering
from this remap bug and the quirk hadn't triggered, because the
revision id register read at a lower value that 0x13, so the quirk
test failed improperly.  Given this, it seems only prudent to adjust
this quirk so that any revision less than 0x13 has the quirk asserted.

[ tglx: Removed the 0x12 comparison of pci id 3405 as this is covered
    	by the <= 0x13 check already ]

Signed-off-by: Neil Horman <nhorman at tuxdriver.com>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Cc: x86 at kernel.org
Link: http://lkml.kernel.org/r/1394649873-14913-1-git-send-email-nhorman@tuxdriver.com
Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/x86/kernel/early-quirks.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index 63bdb29..4f7c82c 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -202,18 +202,15 @@ static void __init intel_remapping_check(int num, int slot, int func)
 	revision = read_pci_config_byte(num, slot, func, PCI_REVISION_ID);

 	/*
- 	 * Revision 13 of all triggering devices id in this quirk have
-	 * a problem draining interrupts when irq remapping is enabled,
-	 * and should be flagged as broken.  Additionally revisions 0x12
-	 * and 0x22 of device id 0x3405 has this problem.
+	 * Revision <= 13 of all triggering devices id in this quirk
+	 * have a problem draining interrupts when irq remapping is
+	 * enabled, and should be flagged as broken. Additionally
+	 * revision 0x22 of device id 0x3405 has this problem.
 	 */
-	if (revision == 0x13)
+	if (revision <= 0x13)
 		set_irq_remapping_broken();
-	else if ((device == 0x3405) &&
-	    ((revision == 0x12) ||
-	     (revision == 0x22)))
+	else if (device == 0x3405 && revision == 0x22)
 		set_irq_remapping_broken();
-
 }

 #define QFLAG_APPLY_ONCE 	0x1
--
1.9.1