ppc/pnv: Create BMC devices at machine init

The BMC of the OpenPOWER systems monitors the machine state using
sensors, controls the power and controls the access to the PNOR flash
device containing the firmware image required to boot the host.

QEMU models the power cycle process, access to the sensors and access
to the PNOR device. But, for these features to be available, the QEMU
PowerNV machine needs two extras devices on the command line, an IPMI
BT device for communication and a BMC backend device:

  -device ipmi-bmc-sim,id=bmc0 -device isa-ipmi-bt,bmc=bmc0,irq=10

The BMC properties are then defined accordingly in the device tree and
OPAL self adapts. If a BMC device and an IPMI BT device are not
available, OPAL does not try to communicate with the BMC in any
manner. This is not how real systems behave.

To be closer to the default behavior, create an IPMI BMC simulator
device and an IPMI BT device at machine initialization time. We loose
the ability to define an external BMC device but there are benefits:

  - a better match with real systems,
  - a better test coverage of the OPAL code,
  - system powerdown and reset commands that work,
  - a QEMU device tree compliant with the specifications (*).

(*) Still needs a MBOX device.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20191121162340.11049-1-clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/pnv.c

@@ -551,27 +551,10 @@ static void pnv_powerdown_notify(Notifier *n, void *opaque)
 
 static void pnv_reset(MachineState *machine)
 {
-    PnvMachineState *pnv = PNV_MACHINE(machine);
     void *fdt;
-    Object *obj;
 
     qemu_devices_reset();
 
-    /*
-     * OpenPOWER systems have a BMC, which can be defined on the
-     * command line with:
-     *
-     *   -device ipmi-bmc-sim,id=bmc0
-     *
-     * This is the internal simulator but it could also be an external
-     * BMC.
-     */
-    obj = object_resolve_path_type("", "ipmi-bmc-sim", NULL);
-    if (obj) {
-        pnv->bmc = IPMI_BMC(obj);
-        pnv_bmc_hiomap(pnv->bmc);
-    }
-
     fdt = pnv_dt_create(machine);
 
     /* Pack resulting tree */
@@ -629,6 +612,16 @@ static bool pnv_match_cpu(const char *default_type, const char *cpu_type)
     return ppc_default->pvr_match(ppc_default, ppc->pvr);
 }
 
+static void pnv_ipmi_bt_init(ISABus *bus, IPMIBmc *bmc, uint32_t irq)
+{
+    Object *obj;
+
+    obj = OBJECT(isa_create(bus, "isa-ipmi-bt"));
+    object_property_set_link(obj, OBJECT(bmc), "bmc", &error_fatal);
+    object_property_set_int(obj, irq, "irq", &error_fatal);
+    object_property_set_bool(obj, true, "realized", &error_fatal);
+}
+
 static void pnv_init(MachineState *machine)
 {
     PnvMachineState *pnv = PNV_MACHINE(machine);
@@ -751,6 +744,9 @@ static void pnv_init(MachineState *machine)
     }
     g_free(chip_typename);
 
+    /* Create the machine BMC simulator */
+    pnv->bmc = pnv_bmc_create();
+
     /* Instantiate ISA bus on chip 0 */
     pnv->isa_bus = pnv_isa_create(pnv->chips[0], &error_fatal);
 
@@ -760,6 +756,9 @@ 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);
+
     /*
      * OpenPOWER systems use a IPMI SEL Event message to notify the
      * host to powerdown

hw/ppc/pnv_bmc.c

@@ -17,6 +17,8 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "qapi/error.h"
 #include "target/ppc/cpu.h"
 #include "qemu/log.h"
 #include "hw/ipmi/ipmi.h"
@@ -211,8 +213,20 @@ static const IPMINetfn hiomap_netfn = {
     .cmd_handlers = hiomap_cmds
 };
 
-int pnv_bmc_hiomap(IPMIBmc *bmc)
+/*
+ * Instantiate the machine BMC. PowerNV uses the QEMU internal
+ * simulator but it could also be external.
+ */
+IPMIBmc *pnv_bmc_create(void)
 {
-    return ipmi_sim_register_netfn(IPMI_BMC_SIMULATOR(bmc),
-                                   IPMI_NETFN_OEM, &hiomap_netfn);
+    Object *obj;
+
+    obj = object_new(TYPE_IPMI_BMC_SIMULATOR);
+    object_property_set_bool(obj, true, "realized", &error_fatal);
+
+    /* Install the HIOMAP protocol handlers to access the PNOR */
+    ipmi_sim_register_netfn(IPMI_BMC_SIMULATOR(obj), IPMI_NETFN_OEM,
+                            &hiomap_netfn);
+
+    return IPMI_BMC(obj);
 }

include/hw/ppc/pnv.h

@@ -198,7 +198,7 @@ static inline bool pnv_is_power9(PnvMachineState *pnv)
  */
 void pnv_dt_bmc_sensors(IPMIBmc *bmc, void *fdt);
 void pnv_bmc_powerdown(IPMIBmc *bmc);
-int pnv_bmc_hiomap(IPMIBmc *bmc);
+IPMIBmc *pnv_bmc_create(void);
 
 /*
  * POWER8 MMIO base addresses