Re: [RFC PATCH 00/13] Add support for Mirror VM.

[Tobin Feldman-Fitzthum <tobin@linux.ibm.com>]

On Mon, Aug 16 at 10:44 AM Ashish Kalra wrote:

 > I am not sure if we really don't need QEMU's MMIO logic, I think that 
once the>
 > mirror VM starts booting and running the UEFI code, it might be only 
during
 > the PEI or DXE phase where it will start actually running the MH code,
 > so mirror VM probably still need to handles KVM_EXIT_IO when SEC 
phase does I/O,
 > I can see PIC accesses and Debug Agent initialization stuff in SEC 
startup code.

The migration handler prototype that we are releasing in the near future 
does not use the SEC or PEI phases in the mirror. We have some support 
code that runs in the main VM and sets up the migration handler entry 
point. QEMU starts the mirror pointing to this entry point, which does 
some more setup (like switching to long mode) and jumps to the migration 
handler.

-Tobin

 > Addtionally this still requires CPUState{..} structure and the backing
 > "X86CPU" structure, for example, as part of kvm_arch_post_run() to get
 > the MemTxAttrs needed by kvm_handle_io().

 > Thanks,
 > Ashish