On Thu, Sep 29, 2022 at 05:33:00PM +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. > > Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx> > Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx> > --- > drivers/iommu/s390-iommu.c | 50 +++++++++++++++++++++++++++----------- > 1 file changed, 36 insertions(+), 14 deletions(-) Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Jason
