> From: Nicolin Chen <nicolinc@xxxxxxxxxx> > Sent: Friday, May 9, 2025 11:03 AM > > To simplify the mappings from global VCMDQs to VINTFs' LVCMDQs, the > design > chose to do static allocations and mappings in the global reset function. > > However, with the user-owned VINTF support, it exposes a security concern: > if user space VM only wants one LVCMDQ for a VINTF, statically mapping two > or more LVCMDQs creates a hidden VCMDQ that user space could DoS attack > by > writing random stuff to overwhelm the kernel with unhandleable IRQs. > > Thus, to support the user-owned VINTF feature, a LVCMDQ mapping has to > be > done dynamically. > > HW allows pre-assigning global VCMDQs in the CMDQ_ALLOC registers, > without > finalizing the mappings by keeping CMDQV_CMDQ_ALLOCATED=0. So, add a > pair > of map/unmap helper that simply sets/clears that bit. > > Delay the LVCMDQ mappings to tegra241_vintf_hw_init(), and the > unmappings > to tegra241_vintf_hw_deinit(). I don't know the specifics of tegra241-cmdqv. But the current description is a bit misleading. for native tegra241_vintf_hw_init() is called from reset so the mapping is still enabled in that path. for user-owned then tegra241_vcmdq_map_lvcmdq() is called from tegra241_vintf_alloc_lvcmdq_user() instead of tegra241_vintf_hw_init(). so nothing is actually delayed in this patch.
