spapr: Do TPM proxy hotplug sanity checks at pre-plug

There can be only one TPM proxy at a time. This is currently
checked at plug time. But this can be detected at pre-plug in
order to error out earlier.

This allows to get rid of error handling in the plug handler.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20201120234208.683521-9-groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 18 insertions, 5 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index ac115b0..d51c550 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -3971,17 +3971,28 @@ static void spapr_phb_unplug_request(HotplugHandler *hotplug_dev,
     }
 }
 
-static void spapr_tpm_proxy_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
-                                 Error **errp)
+static
+bool spapr_tpm_proxy_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                              Error **errp)
 {
     SpaprMachineState *spapr = SPAPR_MACHINE(OBJECT(hotplug_dev));
-    SpaprTpmProxy *tpm_proxy = SPAPR_TPM_PROXY(dev);
 
     if (spapr->tpm_proxy != NULL) {
         error_setg(errp, "Only one TPM proxy can be specified for this machine");
-        return;
+        return false;
     }
 
+    return true;
+}
+
+static void spapr_tpm_proxy_plug(HotplugHandler *hotplug_dev, DeviceState *dev)
+{
+    SpaprMachineState *spapr = SPAPR_MACHINE(OBJECT(hotplug_dev));
+    SpaprTpmProxy *tpm_proxy = SPAPR_TPM_PROXY(dev);
+
+    /* Already checked in spapr_tpm_proxy_pre_plug() */
+    g_assert(spapr->tpm_proxy == NULL);
+
     spapr->tpm_proxy = tpm_proxy;
 }
 
@@ -4004,7 +4015,7 @@ static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_PCI_HOST_BRIDGE)) {
         spapr_phb_plug(hotplug_dev, dev);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_TPM_PROXY)) {
-        spapr_tpm_proxy_plug(hotplug_dev, dev, errp);
+        spapr_tpm_proxy_plug(hotplug_dev, dev);
     }
 }
 
@@ -4067,6 +4078,8 @@ static void spapr_machine_device_pre_plug(HotplugHandler *hotplug_dev,
         spapr_core_pre_plug(hotplug_dev, dev, errp);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_PCI_HOST_BRIDGE)) {
         spapr_phb_pre_plug(hotplug_dev, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_TPM_PROXY)) {
+        spapr_tpm_proxy_pre_plug(hotplug_dev, dev, errp);
     }
 }