Re: [PATCH] ppc/pnv: Create BMC devices only when defaults are enabled

[David Gibson]

On Sat, Apr 04, 2020 at 05:36:55PM +0200, Cédric Le Goater wrote:
> Commit e2392d4395dd ("ppc/pnv: Create BMC devices at machine init")
> introduced default BMC devices which can be a problem when the same
> devices are defined on the command line with :
> 
>   -device ipmi-bmc-sim,id=bmc0 -device isa-ipmi-bt,bmc=bmc0,irq=10
> 
> QEMU fails with :
> 
>   qemu-system-ppc64: error creating device tree: node: FDT_ERR_EXISTS
> 
> Use defaults_enabled() when creating the default BMC devices to let
> the user provide its own BMC devices using '-nodefaults'. If no BMC
> device are provided, output a warning but let QEMU run as this is a
> supported configuration. However, when multiple BMC devices are
> defined, stop QEMU with a clear error as the results are unexpected.
> 
> Fixes: e2392d4395dd ("ppc/pnv: Create BMC devices at machine init")
> Reported-by: Nathan Chancellor <address@hidden>
> Signed-off-by: Cédric Le Goater <address@hidden>

As a regression fix, applied to ppc-for-5.0.

> ---
>  include/hw/ppc/pnv.h |  2 ++
>  hw/ppc/pnv.c         | 32 ++++++++++++++++++++++++++-----
>  hw/ppc/pnv_bmc.c     | 45 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 74 insertions(+), 5 deletions(-)
> 
> diff --git a/include/hw/ppc/pnv.h b/include/hw/ppc/pnv.h
> index fb4d0c0234b3..d4b0b0e2ff71 100644
> --- a/include/hw/ppc/pnv.h
> +++ b/include/hw/ppc/pnv.h
> @@ -241,6 +241,8 @@ struct PnvMachineState {
>  void pnv_dt_bmc_sensors(IPMIBmc *bmc, void *fdt);
>  void pnv_bmc_powerdown(IPMIBmc *bmc);
>  IPMIBmc *pnv_bmc_create(PnvPnor *pnor);
> +IPMIBmc *pnv_bmc_find(Error **errp);
> +void pnv_bmc_set_pnor(IPMIBmc *bmc, PnvPnor *pnor);
>  
>  /*
>   * POWER8 MMIO base addresses
> diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> index ac83b8698b8e..a3b7a8d0ff32 100644
> --- a/hw/ppc/pnv.c
> +++ b/hw/ppc/pnv.c
> @@ -573,10 +573,29 @@ static void pnv_powerdown_notify(Notifier *n, void 
> *opaque)
>  
>  static void pnv_reset(MachineState *machine)
>  {
> +    PnvMachineState *pnv = PNV_MACHINE(machine);
> +    IPMIBmc *bmc;
>      void *fdt;
>  
>      qemu_devices_reset();
>  
> +    /*
> +     * The machine should provide by default an internal BMC simulator.
> +     * If not, try to use the BMC device that was provided on the command
> +     * line.
> +     */
> +    bmc = pnv_bmc_find(&error_fatal);
> +    if (!pnv->bmc) {
> +        if (!bmc) {
> +            warn_report("machine has no BMC device. Use '-device "
> +                        "ipmi-bmc-sim,id=bmc0 -device 
> isa-ipmi-bt,bmc=bmc0,irq=10' "
> +                        "to define one");
> +        } else {
> +            pnv_bmc_set_pnor(bmc, pnv->pnor);
> +            pnv->bmc = bmc;
> +        }
> +    }
> +
>      fdt = pnv_dt_create(machine);
>  
>      /* Pack resulting tree */
> @@ -835,9 +854,6 @@ static void pnv_init(MachineState *machine)
>      }
>      g_free(chip_typename);
>  
> -    /* Create the machine BMC simulator */
> -    pnv->bmc = pnv_bmc_create(pnv->pnor);
> -
>      /* Instantiate ISA bus on chip 0 */
>      pnv->isa_bus = pnv_isa_create(pnv->chips[0], &error_fatal);
>  
> @@ -847,8 +863,14 @@ static void pnv_init(MachineState *machine)
>      /* Create an RTC ISA device too */
>      mc146818_rtc_init(pnv->isa_bus, 2000, NULL);
>  
> -    /* Create the IPMI BT device for communication with the BMC */
> -    pnv_ipmi_bt_init(pnv->isa_bus, pnv->bmc, 10);
> +    /*
> +     * Create the machine BMC simulator and the IPMI BT device for
> +     * communication with the BMC
> +     */
> +    if (defaults_enabled()) {
> +        pnv->bmc = pnv_bmc_create(pnv->pnor);
> +        pnv_ipmi_bt_init(pnv->isa_bus, pnv->bmc, 10);
> +    }
>  
>      /*
>       * OpenPOWER systems use a IPMI SEL Event message to notify the
> diff --git a/hw/ppc/pnv_bmc.c b/hw/ppc/pnv_bmc.c
> index 8863354c1c08..4e018b8b70e4 100644
> --- a/hw/ppc/pnv_bmc.c
> +++ b/hw/ppc/pnv_bmc.c
> @@ -213,6 +213,18 @@ static const IPMINetfn hiomap_netfn = {
>      .cmd_handlers = hiomap_cmds
>  };
>  
> +
> +void pnv_bmc_set_pnor(IPMIBmc *bmc, PnvPnor *pnor)
> +{
> +    object_ref(OBJECT(pnor));
> +    object_property_add_const_link(OBJECT(bmc), "pnor", OBJECT(pnor),
> +                                   &error_abort);
> +
> +    /* Install the HIOMAP protocol handlers to access the PNOR */
> +    ipmi_sim_register_netfn(IPMI_BMC_SIMULATOR(bmc), IPMI_NETFN_OEM,
> +                            &hiomap_netfn);
> +}
> +
>  /*
>   * Instantiate the machine BMC. PowerNV uses the QEMU internal
>   * simulator but it could also be external.
> @@ -232,3 +244,36 @@ IPMIBmc *pnv_bmc_create(PnvPnor *pnor)
>  
>      return IPMI_BMC(obj);
>  }
> +
> +typedef struct ForeachArgs {
> +    const char *name;
> +    Object *obj;
> +} ForeachArgs;
> +
> +static int bmc_find(Object *child, void *opaque)
> +{
> +    ForeachArgs *args = opaque;
> +
> +    if (object_dynamic_cast(child, args->name)) {
> +        if (args->obj) {
> +            return 1;
> +        }
> +        args->obj = child;
> +    }
> +    return 0;
> +}
> +
> +IPMIBmc *pnv_bmc_find(Error **errp)
> +{
> +    ForeachArgs args = { TYPE_IPMI_BMC_SIMULATOR, NULL };
> +    int ret;
> +
> +    ret = object_child_foreach_recursive(object_get_root(), bmc_find, &args);
> +    if (ret) {
> +        error_setg(errp, "machine should have only one BMC device. "
> +                   "Use '-nodefaults'");
> +        return NULL;
> +    }
> +
> +    return args.obj ? IPMI_BMC(args.obj) : NULL;
> +}

-- 
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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