[PATCH kernel] powerpc/powernv: Fix stale iommu table base after VFIO

Michael Ellerman patch-notifications at ellerman.id.au
Mon Jul 8 11:19:43 AEST 2019

On Fri, 2019-06-28 at 06:53:00 UTC, Alexey Kardashevskiy wrote:
> The powernv platform uses @dma_iommu_ops for non-bypass DMA. These ops
> need an iommu_table pointer which is stored in
> dev->archdata.iommu_table_base. It is initialized during
> pcibios_setup_device() which handles boot time devices. However when
> a device is taken from the system in order to pass it through, the default
> IOMMU table is destroyed but the pointer in a device is not updated;
> also when a device is returned back to the system, a new table pointer
> is not stored in dev->archdata.iommu_table_base either. So when a just
> returned device tries using IOMMU, it crashes on accessing stale
> iommu_table or its members.
> This calls set_iommu_table_base() when the default window is created.
> Note it used to be there before but was wrongly removed (see "fixes").
> It did not appear before as these days most devices simply use bypass.
> This adds set_iommu_table_base(NULL) when a device is taken from
> the system to make it clear that IOMMU DMA cannot be used past that point.
> Fixes: c4e9d3c1e65a ("powerpc/powernv/pseries: Rework device adding to IOMMU groups")
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>

Applied to powerpc next, thanks.



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