Re: [PATCH v5 14/29] iommufd/viommu: Add IOMMUFD_CMD_HW_QUEUE_ALLOC ioctl

On Mon, Jun 02, 2025 at 10:41:05PM -0700, Nicolin Chen wrote:

I found that the size_viommu or size_hw_queue might not work using a static macro as that RDMA one does:

• The size in vIOMMU case is type dependent. E.g. smmuv3 driver uses one iommu_ops to support two types: vSMMU and vCMDQ

Maybe they can just be max()'d?

1. Define a get_viommu_size(unsigned int type) op: use a similar macro in the driver function to return with:

#define VIOMMU_STRUCT_SIZE(ib_struct, drv_struct, member) \ (sizeof(drv_struct) + \ BUILD_BUG_ON_ZERO(offsetof(drv_struct, member)) + \ BUILD_BUG_ON_ZERO(!__same_type(((drv_struct *)NULL)->member, \ ib_struct)))

if (type == SMMU) return VIOMMU_STRUCT_SIZE( struct arm_vsmmu, struct iommufd_viommu, core); return 0;

I guess this is best?

2. Let core allocate with sizeof(struct iommufd_viommu), then let driver krealloc during the viommu_init op call:

No.. memmoving things like locks doesn't work.

Jason