[3.19.y-ckt stable] Patch "irqchip/gic-v3-its: Fix double ICC_EOIR write for LPI in EOImode==1" has been added to the 3.19.y-ckt tree

Kamal Mostafa kamal at canonical.com
Wed Mar 9 00:24:41 UTC 2016


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

    irqchip/gic-v3-its: Fix double ICC_EOIR write for LPI in EOImode==1

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt16.

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

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 91198f98de6103e3b880e73de228e30fc0a4bb76 Mon Sep 17 00:00:00 2001
From: Ashok Kumar <ashoks at broadcom.com>
Date: Thu, 11 Feb 2016 05:38:53 -0800
Subject: irqchip/gic-v3-its: Fix double ICC_EOIR write for LPI in EOImode==1

commit 004fa08d7aba2a13974446bf212a48c0b3b0d9fd upstream.

When the GIC is using EOImode==1, the EOI is done immediately,
leaving the deactivation to be performed when the EOI was
previously done.

Unfortunately, the ITS is not aware of the EOImode at all, and
blindly EOIs the interrupt again. On most systems, this is ignored
(despite being a programming error), but some others do raise a
SError exception as there is no priority drop to perform for this
interrupt.

The fix is to stop trying to be clever, and always call into the
underlying GIC to perform the right access, irrespective of the
more we're in.

[Marc: Reworked commit message]

Fixes: 0b996fd35957a ("irqchip/GICv3: Convert to EOImode == 1")
Acked-by: Marc Zyngier <marc.zyngier at arm.com>
Signed-off-by: Ashok Kumar <ashoks at broadcom.com>
Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/irqchip/irq-gic-v3-its.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index d8996bd..0b8e68e 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -564,11 +564,6 @@ static void its_unmask_irq(struct irq_data *d)
 	lpi_set_config(d, true);
 }

-static void its_eoi_irq(struct irq_data *d)
-{
-	gic_write_eoir(d->hwirq);
-}
-
 static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
 			    bool force)
 {
@@ -605,7 +600,7 @@ static struct irq_chip its_irq_chip = {
 	.name			= "ITS",
 	.irq_mask		= its_mask_irq,
 	.irq_unmask		= its_unmask_irq,
-	.irq_eoi		= its_eoi_irq,
+	.irq_eoi		= irq_chip_eoi_parent,
 	.irq_set_affinity	= its_set_affinity,
 	.irq_compose_msi_msg	= its_irq_compose_msi_msg,
 };
--
2.7.0





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