Quoting Claudio Imbrenda (2023-07-05 13:19:36)
> Simplify the shutdown of non-protected VMs. There is no need to do
> complex manipulations of the counter if it was zero.
>
> This also fixes a very rare race which caused pages to be torn down
> from the address space with a non-zero counter even on older machines
> that don't support the UVC instruction, causing a crash.
>
> Reported-by: Marc Hartmayer <mhartmay@xxxxxxxxxxxxx>
> Fixes: fb491d5500a7 ("KVM: s390: pv: asynchronous destroy for reboot")
> Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Reviewed-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
