On Thu, 2022-10-06 at 16:46 +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> > Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx> @Matt, @Jason I did drop the R-b's here because the change Jason suggested of changing the aperture check on attach to a WARN_ON() and checking zdev->start_dma/end_dma on probe is a behavioral change. > --- > 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) > > drivers/iommu/s390-iommu.c | 65 +++++++++++++++++++++++++------------- > 1 file changed, 43 insertions(+), 22 deletions(-) > > diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c > index 9b3ae4b14636..1f6c9bee9a80 100644 > --- a/drivers/iommu/s390-iommu.c ---8<---
