On Thu, May 15, 2025 at 12:21:17PM -0700, Nicolin Chen wrote: > On Thu, May 15, 2025 at 03:56:29PM -0300, Jason Gunthorpe wrote: > > On Thu, May 15, 2025 at 11:52:05AM -0700, Nicolin Chen wrote: > > > On Thu, May 15, 2025 at 02:17:06PM -0300, Jason Gunthorpe wrote: > > > > On Thu, May 08, 2025 at 08:02:39PM -0700, Nicolin Chen wrote: > > > Should the first call return out_data_type=CMDQV while returning > > > the arm_smmu_v3 hw_info data? Otherwise, VMM wouldn't know what > > > to set in the input sub_data_type of the 2nd ioctl? > > > > No, either set a flag in the smmu_v3 hw_info, as you were doing here, > > or just have the vmm probe it. Given the VMM is likely to be told to > > run in vCMDQ mode on the command line try-and-fail doesn't sound so > > bad. > > > > And I guess we don't need a "sub type" just a "requested type" where 0 > > means return the best one and non-zero means return a specific one or > > fail with EOPNOTSUPP. > > OK. I think this would work: > hw_info (req_type=0) => out_data_type=SMMU_V3, flags=HAS_CMDQV > hw_info (req_type=CMDQV) => out_data_type=CMDQV, flags=0
Yeah > Or, would it be simpler by having a sub_data_uptr: > hw_info => out_data_type=SMMU_V3, sub_data_type=CMDQV, > data_uptr=iommu_hw_info_arm_smmuv3, > sub_data_uptr=iommu_hw_info_tegra241_cmdqv > ? I think the former is simpler to code, you can just add the req_type to the signatures and if the driver comes back with a type != req_type the core code will return EOPNOTSUPP Then just match the impl_ops for req_type in the arm driver. Finally we end up with only one ioctl enum number space for the types, which seems appealing. Jason
