Hi Lu, On Friday, August 23, 2019 3:51:11 AM CEST Lu Baolu wrote: > 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
I was using an internal branch based on drm-tip which didn't contain this commit yet. Fortunately it has been already merged into drm-tip over last weekend and has effectively fixed the issue. Thanks, Janusz > 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; > > } > > } > > > > >