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

From: Thomas Huth <thuth@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
	David Gibson <david@gibson.dropbear.id.au>,
	mdroth@linux.vnet.ibm.com, lvivier@redhat.com
Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH] pseries: Correct panic behaviour for pseries machine type
Date: Wed, 7 Jun 2017 19:10:55 +0200	[thread overview]
Message-ID: <9ef08f1d-33d3-4494-2e91-2456d5764ecf@redhat.com> (raw)
In-Reply-To: <75cc682a-4203-30a5-fab3-22f4e1671532@redhat.com>

On 07.06.2017 16:34, Paolo Bonzini wrote:
> 
> 
> On 07/06/2017 09:33, Thomas Huth wrote:
>> On 07.06.2017 09:07, David Gibson wrote:
>>> 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);
>>>  }
>>>  
>>>  static void rtas_set_power_level(PowerPCCPU *cpu, sPAPRMachineState *spapr,
>>>
>>
>> If I get that qemu_system_guest_panicked() function right, it will stop
>> the VM, won't it? That contradicts the LoPAPR spec that says that the
>> RTAS call returns if the "ibm,extended-os-term" property is available in
>> the device tree.
> 
> It does return... but only after the user starts the guest again with
> "cont".

OK, I guess that's enough to say that the "ibm,extended-os-term"
property can stay ... so I think the patch is fine as it is right now.

 Thomas