On 13/10/2023 16:52, Jason Gunthorpe wrote: > On Sat, Sep 23, 2023 at 02:24:56AM +0100, Joao Martins wrote: >> 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 | 8 ++++++-- >> include/uapi/linux/iommufd.h | 3 +++ >> 2 files changed, 9 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c >> index 26a8a818ffa3..32e259245314 100644 >> --- a/drivers/iommu/iommufd/hw_pagetable.c >> +++ b/drivers/iommu/iommufd/hw_pagetable.c >> @@ -83,7 +83,9 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas, >> >> lockdep_assert_held(&ioas->mutex); >> >> - if ((flags & IOMMU_HWPT_ALLOC_NEST_PARENT) && !ops->domain_alloc_user) >> + if ((flags & (IOMMU_HWPT_ALLOC_NEST_PARENT| >> + IOMMU_HWPT_ALLOC_ENFORCE_DIRTY)) && >> + !ops->domain_alloc_user) >> return ERR_PTR(-EOPNOTSUPP); > > This seems strange, why are we testing flags here? shouldn't this just > be > > if (flags && !ops->domain_alloc_user) > return ERR_PTR(-EOPNOTSUPP); > > ? Yeah makes sense, let me switch to that. It achieves the same without into the weeds of missing a flag update. And any flag essentially requires alloc_user regardless. > >> hwpt = iommufd_object_alloc(ictx, hwpt, IOMMUFD_OBJ_HW_PAGETABLE); >> @@ -157,7 +159,9 @@ 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; > > Please checkpatch your stuff, I always do this, and there was no issues reported on this patch. Sometimes there's one or another I ignore albeit very rarely (e.g. passing 1 character post 80 column gap and which fixing makes the code uglier). > and even better feed the patches to > clang-format and do most of what it says. > This one I don't (but I wasn't aware either that it's a thing) > Otherwise seems like the right thing to do > > Jason
