> From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Thursday, October 10, 2024 12:23 AM > > For SMMUv3 a IOMMU_DOMAIN_NESTED is composed of a S2 > iommu_domain acting > as the parent and a user provided STE fragment that defines the CD table > and related data with addresses translated by the S2 iommu_domain. > > The kernel only permits userspace to control certain allowed bits of the > STE that are safe for user/guest control. > > IOTLB maintenance is a bit subtle here, the S1 implicitly includes the S2 > translation, but there is no way of knowing which S1 entries refer to a > range of S2. > > For the IOTLB we follow ARM's guidance and issue a > CMDQ_OP_TLBI_NH_ALL to > flush all ASIDs from the VMID after flushing the S2 on any change to the > S2. > > Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
