This is a note to let you know that I've just added the patch titled
iommu/vt-d: Fix PCI bus rescan device hot add
to the 4.9-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:
iommu-vt-d-fix-pci-bus-rescan-device-hot-add.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 316f92a705a4c2bf4712135180d56f3cca09243a Mon Sep 17 00:00:00 2001
From: Yian Chen <yian.chen@xxxxxxxxx>
Date: Fri, 20 May 2022 17:21:15 -0700
Subject: iommu/vt-d: Fix PCI bus rescan device hot add
From: Yian Chen <yian.chen@xxxxxxxxx>
commit 316f92a705a4c2bf4712135180d56f3cca09243a upstream.
Notifier calling chain uses priority to determine the execution
order of the notifiers or listeners registered to the chain.
PCI bus device hot add utilizes the notification mechanism.
The current code sets low priority (INT_MIN) to Intel
dmar_pci_bus_notifier and postpones DMAR decoding after adding
new device into IOMMU. The result is that struct device pointer
cannot be found in DRHD search for the new device's DMAR/IOMMU.
Subsequently, the device is put under the "catch-all" IOMMU
instead of the correct one. This could cause system hang when
device TLB invalidation is sent to the wrong IOMMU. Invalidation
timeout error and hard lockup have been observed and data
inconsistency/crush may occur as well.
This patch fixes the issue by setting a positive priority(1) for
dmar_pci_bus_notifier while the priority of IOMMU bus notifier
uses the default value(0), therefore DMAR decoding will be in
advance of DRHD search for a new device to find the correct IOMMU.
Following is a 2-step example that triggers the bug by simulating
PCI device hot add behavior in Intel Sapphire Rapids server.
echo 1 > /sys/bus/pci/devices/0000:6a:01.0/remove
echo 1 > /sys/bus/pci/rescan
Fixes: 59ce0515cdaf ("iommu/vt-d: Update DRHD/RMRR/ATSR device scope")
Cc: stable@xxxxxxxxxxxxxxx # v3.15+
Reported-by: Zhang, Bernice <bernice.zhang@xxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Signed-off-by: Yian Chen <yian.chen@xxxxxxxxx>
Link: https://lore.kernel.org/r/20220521002115.1624069-1-yian.chen@xxxxxxxxx
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/iommu/dmar.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -373,7 +373,7 @@ static int dmar_pci_bus_notifier(struct
static struct notifier_block dmar_pci_bus_nb = {
.notifier_call = dmar_pci_bus_notifier,
- .priority = INT_MIN,
+ .priority = 1,
};
static struct dmar_drhd_unit *
Patches currently in stable-queue which might be from yian.chen@xxxxxxxxx are
queue-4.9/iommu-vt-d-fix-pci-bus-rescan-device-hot-add.patch
