On Mon, Oct 17, 2022 at 02:45:55PM +0200, Niklas Schnelle wrote: > The s390 IOMMU driver currently sets the IOMMU domain's aperture to > match the device specific DMA address range of the device that is first > attached. This is not ideal. For one if the domain has no device > attached in the meantime the aperture could be shrunk allowing > translations outside the aperture to exist in the translation tables. > Also this is a bit of a misuse of the aperture which really should > describe what addresses can be translated and not some device specific > limitations. > > Instead of misusing the aperture like this we can instead create > reserved ranges for the ranges inaccessible to the attached devices > allowing devices with overlapping ranges to still share an IOMMU domain. > This also significantly simplifies s390_iommu_attach_device() allowing > us to move the aperture check to the beginning of the function and > removing the need to hold the device list's lock to check the aperture. > > As we then use the same aperture for all domains and it only depends on > the table properties we can already check zdev->start_dma/end_dma at > probe time and turn the check on attach into a WARN_ON(). > > Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx> > Reviewed-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx> > Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx> > --- > v5->v6: > - Return -EINVAL after WARN_ON() in attach > v4->v5: > - Make aperture check in attach a WARN_ON() and fail in probe if > zdev->start_dma/end_dma doesn't git in aperture (Jason) Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Jason
