ppc/pnv: Create BMC devices only when defaults are enabled

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 <natechancellor@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20200404153655.166834-1-clg@kaod.org>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 45 insertions, 0 deletions

diff --git a/hw/ppc/pnv_bmc.c b/hw/ppc/pnv_bmc.c
index 8863354c1c..4e018b8b70 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;
+}