[PATCH RFC V3 22/29] arm/virt: Update the guest(via GED) about CPU hot-(un)plug events

[Salil Mehta]

During any vCPU hot-(un)plug, running guest VM needs to be intimated about the
new vCPU being added or request the deletion of the vCPU which is already part
of the guest VM. This is done using the ACPI GED event which eventually gets
demultiplexed to a CPU hotplug event and further to specific hot-(un)plug event
of a particular vCPU.

This change adds the ACPI calls to the existing hot-(un)plug hooks to trigger
ACPI GED events from QEMU to guest VM.

Co-developed-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
---
 hw/arm/virt.c | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 9f7e07bd8e..4fa2b7d9e7 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -3169,6 +3169,7 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev, 
DeviceState *dev,
     VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
     MachineState *ms = MACHINE(hotplug_dev);
     CPUState *cs = CPU(dev);
+    Error *local_err = NULL;
     CPUArchId *cpu_slot;
 
     /* insert the cold/hot-plugged vcpu in the slot */
@@ -3181,12 +3182,18 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev, 
DeviceState *dev,
      * plugged, guest is also notified.
      */
     if (vms->acpi_dev) {
-        /* TODO: update acpi hotplug state. Send cpu hotplug event to guest */
+        HotplugHandlerClass *hhc;
+        /* update acpi hotplug state and send cpu hotplug event to guest */
+        hhc = HOTPLUG_HANDLER_GET_CLASS(vms->acpi_dev);
+        hhc->plug(HOTPLUG_HANDLER(vms->acpi_dev), dev, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
         /* TODO: register cpu for reset & update F/W info for the next boot */
     }
 
     cs->disabled = false;
-    return;
 }
 
 static void virt_cpu_unplug_request(HotplugHandler *hotplug_dev,
@@ -3194,8 +3201,10 @@ static void virt_cpu_unplug_request(HotplugHandler 
*hotplug_dev,
 {
     MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());
     VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
+    HotplugHandlerClass *hhc;
     ARMCPU *cpu = ARM_CPU(dev);
     CPUState *cs = CPU(dev);
+    Error *local_err = NULL;
 
     if (!vms->acpi_dev || !dev->realized) {
         error_setg(errp, "GED does not exists or device is not realized!");
@@ -3214,9 +3223,12 @@ static void virt_cpu_unplug_request(HotplugHandler 
*hotplug_dev,
         return;
     }
 
-    /* TODO: request cpu hotplug from guest */
-
-    return;
+    /* request cpu hotplug from guest */
+    hhc = HOTPLUG_HANDLER_GET_CLASS(vms->acpi_dev);
+    hhc->unplug_request(HOTPLUG_HANDLER(vms->acpi_dev), dev, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+    }
 }
 
 static void virt_cpu_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
@@ -3224,7 +3236,9 @@ static void virt_cpu_unplug(HotplugHandler *hotplug_dev, 
DeviceState *dev,
 {
     VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
     MachineState *ms = MACHINE(hotplug_dev);
+    HotplugHandlerClass *hhc;
     CPUState *cs = CPU(dev);
+    Error *local_err = NULL;
     CPUArchId *cpu_slot;
 
     if (!vms->acpi_dev || !dev->realized) {
@@ -3234,7 +3248,13 @@ static void virt_cpu_unplug(HotplugHandler *hotplug_dev, 
DeviceState *dev,
 
     cpu_slot = virt_find_cpu_slot(ms, cs->cpu_index);
 
-    /* TODO: update the acpi cpu hotplug state for cpu hot-unplug */
+    /* update the acpi cpu hotplug state for cpu hot-unplug */
+    hhc = HOTPLUG_HANDLER_GET_CLASS(vms->acpi_dev);
+    hhc->unplug(HOTPLUG_HANDLER(vms->acpi_dev), dev, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
 
     unwire_gic_cpu_irqs(vms, cs);
     virt_update_gic(vms, cs);
@@ -3246,8 +3266,6 @@ static void virt_cpu_unplug(HotplugHandler *hotplug_dev, 
DeviceState *dev,
 
     cpu_slot->cpu = NULL;
     cs->disabled = true;
-
-    return;
 }
 
 static void virt_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
-- 
2.34.1