On 11/27/22 16:58, Dexuan Cui wrote: > +u64 hv_tdx_hypercall(u64 control, u64 input_addr, u64 output_addr) > +{ > + struct tdx_hypercall_args args = { }; > + > + if (!(control & HV_HYPERCALL_FAST_BIT)) { > + if (input_addr) > + input_addr += ms_hyperv.shared_gpa_boundary; > + > + if (output_addr) > + output_addr += ms_hyperv.shared_gpa_boundary; > + } This: > https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/hypercall-interface makes it sound like HV_HYPERCALL_FAST_BIT says whether arguments go in registers (fast) or memory (slow). But this hv_tdx_hypercall() function looks like it takes addresses only. *Is* there a register based calling convention to make Hyper-V hypercalls when running under TDX? Also, is this the output address manipulation fundamentally different from: output_addr = cc_mkdec(output_addr); ? Decrypted addresses are the shared ones, right?