Hi,
On 8/22/19 10:29 PM, Janusz Krzysztofik wrote:
When a perfectly working i915 device is hot unplugged (via sysfs) and
hot re-plugged again, its dev->archdata.iommu field is not populated
again with an IOMMU pointer. As a result, the device probe fails on
DMA mapping error during scratch page setup.
It looks like that happens because devices are not detached from their
MMUIO bus before they are removed on device unplug. Then, when an
already registered device/IOMMU association is identified by the
reinstantiated device's bus and function IDs on IOMMU bus re-attach
attempt, the device's archdata is not populated with IOMMU information
and the bad happens.
I'm not sure if this is a proper fix but it works for me so at least it
confirms correctness of my analysis results, I believe. So far I
haven't been able to identify a good place where the possibly missing
IOMMU bus detach on device unplug operation could be added.
Which kernel version are you testing with? Does it contain below commit?
commit 458b7c8e0dde12d140e3472b80919cbb9ae793f4
Author: Lu Baolu <baolu...@linux.intel.com>
Date: Thu Aug 1 11:14:58 2019 +0800
iommu/vt-d: Detach domain when move device out of group
When removing a device from an iommu group, the domain should
be detached from the device. Otherwise, the stale domain info
will still be cached by the driver and the driver will refuse
to attach any domain to the device again.
Cc: Ashok Raj <ashok....@intel.com>
Cc: Jacob Pan <jacob.jun....@linux.intel.com>
Cc: Kevin Tian <kevin.t...@intel.com>
Fixes: b7297783c2bb6 ("iommu/vt-d: Remove duplicated code for
device hotplug")
Reported-and-tested-by: Vlad Buslov <vla...@mellanox.com>
Suggested-by: Robin Murphy <robin.mur...@arm.com>
Link: https://lkml.org/lkml/2019/7/26/1133
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
Signed-off-by: Joerg Roedel <jroe...@suse.de>
Best regards,
Lu Baolu
Signed-off-by: Janusz Krzysztofik <janusz.krzyszto...@linux.intel.com>
---
drivers/iommu/intel-iommu.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 12d094d08c0a..7cdcd0595408 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2477,6 +2477,9 @@ static struct dmar_domain
*dmar_insert_one_dev_info(struct intel_iommu *iommu,
if (info2) {
found = info2->domain;
info2->dev = dev;
+
+ if (dev && !dev->archdata.iommu)
+ dev->archdata.iommu = info2;
}
}
