Re: [Qemu-devel] [PATCH] pseries: Correct panic behaviour for pseries machine type

From: David Gibson <david@gibson.dropbear.id.au>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: mdroth@linux.vnet.ibm.com, thuth@redhat.com, lvivier@redhat.com,
	qemu-ppc@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] pseries: Correct panic behaviour for pseries machine type
Date: Wed, 7 Jun 2017 21:16:11 +1000	[thread overview]
Message-ID: <20170607111611.GK13397@umbus.fritz.box> (raw)
In-Reply-To: <1799129848.6598516.1496820296394.JavaMail.zimbra@redhat.com>

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On Wed, Jun 07, 2017 at 03:24:56AM -0400, Paolo Bonzini wrote:
> 
> 
> ----- Original Message -----
> > From: "David Gibson" <david@gibson.dropbear.id.au>
> > To: mdroth@linux.vnet.ibm.com, thuth@redhat.com, lvivier@redhat.com
> > Cc: pbonzini@redhat.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org, "David Gibson" <david@gibson.dropbear.id.au>
> > Sent: Wednesday, June 7, 2017 9:07:32 AM
> > Subject: [PATCH] pseries: Correct panic behaviour for pseries machine type
> > 
> > The pseries machine type doesn't usually use the 'pvpanic' device as such,
> > because it has a firmware/hypervisor facility with roughly the same
> > purpose.  The 'ibm,os-term' RTAS call notifies the hypervisor that the
> > guest has crashed.
> > 
> > Our implementation of this call was sending a GUEST_PANICKED qmp event;
> > however, it was not doing the other usual panic actions, making its
> > behaviour different from pvpanic for no good reason.
> > 
> > To correct this, we should call qemu_system_guest_panicked() rather than
> > directly sending the panic event.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  hw/ppc/spapr_rtas.c | 7 ++-----
> >  1 file changed, 2 insertions(+), 5 deletions(-)
> > 
> > diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> > index 707c4d4..94a2799 100644
> > --- a/hw/ppc/spapr_rtas.c
> > +++ b/hw/ppc/spapr_rtas.c
> > @@ -293,12 +293,9 @@ static void rtas_ibm_os_term(PowerPCCPU *cpu,
> >                              target_ulong args,
> >                              uint32_t nret, target_ulong rets)
> >  {
> > -    target_ulong ret = 0;
> > +    qemu_system_guest_panicked(NULL);
> >  
> > -    qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_PAUSE, false, NULL,
> > -                                   &error_abort);
> > -
> > -    rtas_st(rets, 0, ret);
> > +    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
> >  }
> 
> It's possible to "cont" a panicked guest, so I think you should keep
> the rtas_st.

I did keep the rtas_st(), I just changed it to using a constant
instead of an always-0 variable.

-- 
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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