Hi Joerg,
> Hi,
>
> here is the second version of this patch-set. The first version with
> some more introductory text can be found here:
>
> https://lore.kernel.org/lkml/20200407183742.4344-1-j...@8bytes.org/
Thanks for the continued improvements in this area!
I may have spotted a problem with setups like VMD.
The core PCI bus is set up during early boot.
Then, for the PCI bus, we reach iommu_bus_init() -> bus_iommu_probe().
In there, we call probe_iommu_group() -> dev_iommu_get() for each PCI
device, which allocates dev->iommu in each case. So far so good.
The problem is that this is the last time that we'll call dev_iommu_get().
If any PCI bus devices get added after this point, they do not get passed
to dev_iommu_get().
So when the vmd module gets loaded later, and creates more PCI devices,
we end up in iommu_bus_notifier() -> iommu_probe_device()
-> __iommu_probe_device() which does:
dev->iommu->iommu_dev = iommu_dev;
dev->iommu-> is a NULL dereference because dev_iommu_get() was never
called for this new device.
Daniel
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