On Thu, Apr 22, 2021 at 11:42:19AM +0200, Jean-Philippe Brucker wrote:
> Since commit 08a27c1c3ecf ("iommu: Add support to change default domain
> of an iommu group") a user can switch a device between IOMMU and direct
> DMA through sysfs. This doesn't work for AMD IOMMU at the moment because
> dev->dma_ops is not cleared when switching from a DMA to an identity
> IOMMU domain. The DMA layer thus attempts to use the dma-iommu ops on an
> identity domain, causing an oops:
>
> # echo 0000:00:05.0 > /sys/sys/bus/pci/drivers/e1000e/unbind
> # echo identity > /sys/bus/pci/devices/0000:00:05.0/iommu_group/type
> # echo 0000:00:05.0 > /sys/sys/bus/pci/drivers/e1000e/bind
> ...
> BUG: kernel NULL pointer dereference, address: 0000000000000028
> ...
> Call Trace:
> iommu_dma_alloc
> e1000e_setup_tx_resources
> e1000e_open
>
> Since iommu_change_dev_def_domain() calls probe_finalize() again, clear
> the dma_ops there like Vt-d does.
>
> Fixes: 08a27c1c3ecf ("iommu: Add support to change default domain of an iommu
> group")
> Signed-off-by: Jean-Philippe Brucker <jean-phili...@linaro.org>
Applied for v5.13, thanks Jean-Philippe.
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