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

From: Paolo Bonzini <pbonzini@redhat.com>
To: David Gibson <david@gibson.dropbear.id.au>
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 03:24:56 -0400 (EDT)	[thread overview]
Message-ID: <1799129848.6598516.1496820296394.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <20170607070732.23312-1-david@gibson.dropbear.id.au>

----- 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.

Paolo