Re: [qemu-s390x] [PATCH v1] s390x: refactor reset/reipl handling

[Thomas Huth]

On 24.04.2018 12:18, David Hildenbrand wrote:
> Calling pause_all_vcpus()/resume_all_vcpus() from a VCPU thread might
> not be the best idea. As pause_all_vcpus() temporarily drops the qemu
> mutex, two parallel calls to pause_all_vcpus() can be active at a time,
> resulting in a deadlock. (either by two VCPUs or by the main thread and a
> VCPU)
> 
> Let's handle it via the main loop instead, as suggested by Paolo. If we
> would have two parallel reset requests by two different VCPUs at the
> same time, the last one would win.
> 
> We use the existing ipl device to handle it. The nice side effect is
> that we can get rid of reipl_requested.
> 
> This change implies that all reset handling now goes via the common
> path, so "no-reboot" handling is now active for all kinds of reboots.
> 
> Let's execute any CPU initialization code on the target CPU using
> run_on_cpu.
> 
> Signed-off-by: David Hildenbrand <address@hidden>
> ---
> 
> RFC -> v1:
> - initital -> initial
> - get rid of goto
> - store CPU index instead of CPU. Fallback to any CPU in case not found
> - handle default case in switch-case
> 
>  hw/s390x/ipl.c                     | 43 +++++++++++++++++++++++----
>  hw/s390x/ipl.h                     | 16 ++++++++--
>  hw/s390x/s390-virtio-ccw.c         | 51 ++++++++++++++++++++++++++-----
>  include/hw/s390x/s390-virtio-ccw.h |  2 --
>  target/s390x/cpu.h                 | 26 ++++++++++++++++
>  target/s390x/diag.c                | 61 
> +++-----------------------------------
>  target/s390x/internal.h            |  6 ----
>  target/s390x/kvm.c                 |  2 +-
>  8 files changed, 127 insertions(+), 80 deletions(-)

I'm not an expert in all this s390x reset stuff, but as far as I can
see, this looks sane.

Acked-by: Thomas Huth <address@hidden>