[Qemu-ppc] [PATCH 06/10] spapr: add hotplug interrupt machine options

[Michael Roth]

This adds machine options of the form:

  -machine pseries,modern-hotplug-events=true
  -machine pseries,modern-hotplug-events=false

If false, QEMU will force the use of "legacy" style hotplug events,
which are surfaced through EPOW events instead of a dedicated
hot plug event source, and lack certain features necessary, mainly,
for memory unplug support.

If true, QEMU will enable support for "modern" dedicated hot plug
event source. Note that we will still default to "legacy" style unless
the guest advertises support for the "modern" hotplug events via
ibm,client-architecture-support hcall during early boot.

For pseries-2.7 and earlier we default to false, for newer machine
types we default to true.

Signed-off-by: Michael Roth <address@hidden>
---
 hw/ppc/spapr.c              | 33 +++++++++++++++++++++++++++++++++
 include/hw/ppc/spapr.h      |  1 +
 include/hw/ppc/spapr_ovec.h |  1 +
 3 files changed, 35 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 828072a..a3ea140 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1789,6 +1789,11 @@ static void ppc_spapr_init(MachineState *machine)
 
     spapr_ovec_set(spapr->ov5, OV5_FORM1_AFFINITY);
 
+    /* advertise support for dedicated HP event source to guests */
+    if (spapr->use_hotplug_event_source) {
+        spapr_ovec_set(spapr->ov5, OV5_HP_EVT);
+    }
+
     /* init CPUs */
     if (machine->cpu_model == NULL) {
         machine->cpu_model = kvm_enabled() ? "host" : smc->tcg_default_cpu;
@@ -2138,16 +2143,41 @@ static void spapr_set_kvm_type(Object *obj, const char 
*value, Error **errp)
     spapr->kvm_type = g_strdup(value);
 }
 
+static bool spapr_get_modern_hotplug_events(Object *obj, Error **errp)
+{
+    sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
+
+    return spapr->use_hotplug_event_source;
+}
+
+static void spapr_set_modern_hotplug_events(Object *obj, bool value,
+                                            Error **errp)
+{
+    sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
+
+    spapr->use_hotplug_event_source = value;
+}
+
 static void spapr_machine_initfn(Object *obj)
 {
     sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
 
     spapr->htab_fd = -1;
+    spapr->use_hotplug_event_source = true;
     object_property_add_str(obj, "kvm-type",
                             spapr_get_kvm_type, spapr_set_kvm_type, NULL);
     object_property_set_description(obj, "kvm-type",
                                     "Specifies the KVM virtualization mode 
(HV, PR)",
                                     NULL);
+    object_property_add_bool(obj, "modern-hotplug-events",
+                            spapr_get_modern_hotplug_events,
+                            spapr_set_modern_hotplug_events,
+                            NULL);
+    object_property_set_description(obj, "modern-hotplug-events",
+                                    "Use dedicated hotplug event mechanism in"
+                                    " place of standard EPOW events when 
possible"
+                                    " (required for memory hot-unplug 
support)",
+                                    NULL);
 }
 
 static void spapr_machine_finalizefn(Object *obj)
@@ -2594,7 +2624,10 @@ static void phb_placement_2_7(sPAPRMachineState *spapr, 
uint32_t index,
 
 static void spapr_machine_2_7_instance_options(MachineState *machine)
 {
+    sPAPRMachineState *spapr = SPAPR_MACHINE(machine);
+
     spapr_machine_2_8_instance_options(machine);
+    spapr->use_hotplug_event_source = false;
 }
 
 static void spapr_machine_2_7_class_options(MachineClass *mc)
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index b6f9f1b..851f536 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -80,6 +80,7 @@ struct sPAPRMachineState {
     uint32_t check_exception_irq;
     Notifier epow_notifier;
     QTAILQ_HEAD(, sPAPREventLogEntry) pending_events;
+    bool use_hotplug_event_source;
 
     /* Migration state */
     int htab_save_index;
diff --git a/include/hw/ppc/spapr_ovec.h b/include/hw/ppc/spapr_ovec.h
index 47fa04c..92167c6 100644
--- a/include/hw/ppc/spapr_ovec.h
+++ b/include/hw/ppc/spapr_ovec.h
@@ -45,6 +45,7 @@ typedef struct sPAPROptionVector sPAPROptionVector;
 /* option vector 5 */
 #define OV5_DRCONF_MEMORY       OV_BIT(2, 2)
 #define OV5_FORM1_AFFINITY      OV_BIT(5, 0)
+#define OV5_HP_EVT              OV_BIT(6, 5)
 
 /* interfaces */
 sPAPROptionVector *spapr_ovec_new(void);
-- 
1.9.1