Re: [Qemu-ppc] [PATCH 7/7] spapr: Perform machine reset in a more sensible order

[David Gibson]

On Wed, Sep 11, 2019 at 05:40:58PM +1000, Alexey Kardashevskiy wrote:
> 
> 
> On 11/09/2019 14:04, David Gibson wrote:
> > We've made several changes in the past to the machine reset order to fix
> > specific problems.  However, we've ended up with an order that doesn't make
> > a lot of logical sense.  This is an attempt to rectify this.
> > 
> > First we reset global CAS options, since that should depend on nothing
> > else.  Then we reset the CPUs, which shouldn't depend on external devices.
> > Then the irq subsystem, then the bulk of devices (which might rely on
> > irqs).  Finally we set up the entry state ready for boot, which could
> > potentially rely on a bunch of other things.
> > 
> > Signed-off-by: David Gibson <address@hidden>
> 
> 
> Breaks console on P8 and asserts on rebooting a P9 guest.

Yeah, I jumped the gun on this one - I need to rethink and test more thoroughly.

> 
> 
> 
> > ---
> >  hw/ppc/spapr.c | 47 +++++++++++++++++++++++++----------------------
> >  1 file changed, 25 insertions(+), 22 deletions(-)
> > 
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 5a919a6cc1..1560a11738 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -1724,6 +1724,28 @@ static void spapr_machine_reset(MachineState 
> > *machine)
> >      void *fdt;
> >      int rc;
> >  
> > +    /*
> > +     * If this reset wasn't generated by CAS, we should reset our
> > +     * negotiated options and start from scratch
> > +     */
> > +    if (!spapr->cas_reboot) {
> > +        spapr_ovec_cleanup(spapr->ov5_cas);
> > +        spapr->ov5_cas = spapr_ovec_new();
> > +
> > +        ppc_set_compat_all(spapr->max_compat_pvr, &error_fatal);
> > +    }
> > +
> > +    /*
> > +     * There is no CAS under qtest. Simulate one to please the code that
> > +     * depends on spapr->ov5_cas. This is especially needed to test device
> > +     * unplug, so we do that before resetting the DRCs.
> > +     */
> > +    if (qtest_enabled()) {
> > +        spapr_ovec_cleanup(spapr->ov5_cas);
> > +        spapr->ov5_cas = spapr_ovec_clone(spapr->ov5);
> > +    }
> > +
> > +    /* Reset the CPUs */
> >      spapr_caps_apply(spapr);
> >  
> >      first_ppc_cpu = POWERPC_CPU(first_cpu);
> > @@ -1741,34 +1763,15 @@ static void spapr_machine_reset(MachineState 
> > *machine)
> >          spapr_setup_hpt_and_vrma(spapr);
> >      }
> >  
> > -    qemu_devices_reset();
> > -
> > -    /*
> > -     * If this reset wasn't generated by CAS, we should reset our
> > -     * negotiated options and start from scratch
> > -     */
> > -    if (!spapr->cas_reboot) {
> > -        spapr_ovec_cleanup(spapr->ov5_cas);
> > -        spapr->ov5_cas = spapr_ovec_new();
> > -
> > -        ppc_set_compat_all(spapr->max_compat_pvr, &error_fatal);
> > -    }
> > -
> > +    /* Reset IRQ subsystem */
> >      /*
> >       * This is fixing some of the default configuration of the XIVE
> >       * devices. To be called after the reset of the machine devices.
> >       */
> >      spapr_irq_reset(spapr, &error_fatal);
> >  
> > -    /*
> > -     * There is no CAS under qtest. Simulate one to please the code that
> > -     * depends on spapr->ov5_cas. This is especially needed to test device
> > -     * unplug, so we do that before resetting the DRCs.
> > -     */
> > -    if (qtest_enabled()) {
> > -        spapr_ovec_cleanup(spapr->ov5_cas);
> > -        spapr->ov5_cas = spapr_ovec_clone(spapr->ov5);
> > -    }
> > +    /* Reset other devices */
> > +    qemu_devices_reset();
> >  
> >      /* DRC reset may cause a device to be unplugged. This will cause 
> > troubles
> >       * if this device is used by another device (eg, a running vhost 
> > backend
> > 
> 

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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