Re: [RFC PATCH v4 18/36] i386/tdx: Skip BIOS shadowing setup

[Gerd Hoffmann]

  Hi,

> I did some tracing for this, and the result differs for q35 machine type and
> pc machine type.
> 
> - For q35, the memslot update for isa-bios/pc.rom happens when mc->reset()
> that is triggered via
> 
>   qdev_machine_creation_done()
>     -> qemu_system_reset(SHUTDOWN_CASE_NONE);
> 
> It's surely later than TDX's machine_init_done_notify callback which
> initializes the part of private memory via KVM_TDX_INIT_MEM_REGION
> 
> - For pc machine type, the memslot update happens in i440fx_init(), which is
> earlier than TDX's machine_init_done_notify callback
> 
> I haven't fully understand in what condition will QEMU carry out the memslot
> update yet. I will keep learning and try to come up a solution to ensure
> TDX's machine_init_done_notify callback executed after all the memslot
> settle down.

My guess would be the rom shadowing initialization being slightly
different in 'pc' and 'q35'.

take care,
  Gerd