> From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Friday, February 10, 2023 4:45 AM > > On Wed, Feb 08, 2023 at 08:31:45PM -0800, Yi Liu wrote: > > Today iommufd allocates the kernel-managed hw_pagetabe implicitly > when > > device is attached to an IOAS. This links the hw_pagetable to IOPT within > > IOAS. > > > > However, this is not the perfect way. It makes much sense to let > userspace > > explicitly request hw_pagtable allocation via iommufd. The reason is even > > though the hw_pagetable is kernel-managed, the mappings are feed by > > userspace. Also, this makes the lifecircle of kernel-managed > hw_pagetable > > more clear during usage. This is very important in the usage of nested > > translation, in which the kernel-managed hw_pagetable would be used as > the > > stage-2 hw_pagetable. In such case, both stage-1 and stage-2 > hw_pagetable > > should be allocated by userspace to ensure the life-circle. > > > > This adds an ioctl IOMMU_HWPT_ALLOC for the hw_pagetable allocation. > For > > kernel-managed hw_pagetable, userspace should provide an IOAS ID in > the > > allocation request. > > > > Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx> > > Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx> > > --- > > drivers/iommu/iommufd/device.c | 11 ++- > > drivers/iommu/iommufd/hw_pagetable.c | 116 > ++++++++++++++++++++++++ > > drivers/iommu/iommufd/iommufd_private.h | 15 +++ > > drivers/iommu/iommufd/main.c | 3 + > > include/uapi/linux/iommufd.h | 48 ++++++++++ > > 5 files changed, 191 insertions(+), 2 deletions(-) > > This patch and its requirements should all be first in the series. A > mini series who's only job is to add IOMMU_HWPT_ALLOC > > Then patches to add IOMMU_HWPT_INVALIDATE > > Then the vt-d implementation of all this, including the vt-d specific > changes to the uapi/etc. Ok. will reorder in next version. Regards, Yi Liu
