Re: [PATCH v4 13/21] iommu/riscv: Preserve MSI IOVA state across domain replacement

[Andrew Jones]

On Thu, Aug 20, 2026 at 06:52:04PM -0300, Jason Gunthorpe wrote:
> On Thu, Aug 20, 2026 at 11:41:42PM +0200, Andrew Jones wrote:
> > MSI IOVAs belong to a paging domain, but iommufd may replace a device's
> > domain while its interrupts remain allocated. Waiting for another IRQ
> > allocation to populate the new table would leave existing interrupts
> > without valid MSI IOVAs.
> 
> ???
> 
> iommufd is supposed to handle all of this itself, that is what commit
> 40f5175d0eb7 ("iommufd: Implement sw_msi support natively")
> 
> is doing?
> 
> The whole point of that commit was so drivers don't have to deal with
> this at all.
>

This driver relies on that support. iommufd installs all required MSI
mappings in the incoming HWPT before attach. The additional driver work
is to populate the PA-to-IOVA lookup table riscv needs in MSI composition
on IRQ affinity changes.

Thanks,
drew