Throughout IOMMU domain lifetime that wants to use dirty tracking, some guarantees are needed such that any device attached to the iommu_domain supports dirty tracking. The idea is to handle a case where IOMMU in the system are assymetric feature-wise and thus the capability may not be supported for all devices. The enforcement is done by adding a flag into HWPT_ALLOC namely: IOMMUFD_HWPT_ALLOC_ENFORCE_DIRTY .. Passed in HWPT_ALLOC ioctl() flags. The enforcement is done by creating a iommu_domain via domain_alloc_user() and validating the requested flags with what the device IOMMU supports (and failing accordingly) advertised). Advertising the new IOMMU domain feature flag requires that the individual iommu driver capability is supported when a future device attachment happens. Link: https://lore.kernel.org/kvm/20220721142421.GB4609@xxxxxxxxxx/ Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx> --- drivers/iommu/iommufd/hw_pagetable.c | 4 +++- include/uapi/linux/iommufd.h | 3 +++ 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c index 8b3d2875d642..2b9ff3850bb8 100644 --- a/drivers/iommu/iommufd/hw_pagetable.c +++ b/drivers/iommu/iommufd/hw_pagetable.c @@ -157,7 +157,9 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd) struct iommufd_ioas *ioas; int rc; - if ((cmd->flags & (~IOMMU_HWPT_ALLOC_NEST_PARENT)) || cmd->__reserved) + if ((cmd->flags & + ~(IOMMU_HWPT_ALLOC_NEST_PARENT|IOMMU_HWPT_ALLOC_ENFORCE_DIRTY)) || + cmd->__reserved) return -EOPNOTSUPP; idev = iommufd_get_device(ucmd, cmd->dev_id); diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h index 4a7c5c8fdbb4..cd94a9d8ce66 100644 --- a/include/uapi/linux/iommufd.h +++ b/include/uapi/linux/iommufd.h @@ -352,9 +352,12 @@ struct iommu_vfio_ioas { * @IOMMU_HWPT_ALLOC_NEST_PARENT: If set, allocate a domain which can serve * as the parent domain in the nesting * configuration. + * @IOMMU_HWPT_ALLOC_ENFORCE_DIRTY: Dirty tracking support for device IOMMU is + * enforced on device attachment */ enum iommufd_hwpt_alloc_flags { IOMMU_HWPT_ALLOC_NEST_PARENT = 1 << 0, + IOMMU_HWPT_ALLOC_ENFORCE_DIRTY = 1 << 1, }; /** -- 2.17.2
