[PATCH RFC V2 29/37] 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: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
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 | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index b447e86fb6..6f5ee4a1c6 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -3157,6 +3157,7 @@ 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 */
@@ -3169,12 +3170,20 @@ 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) {
+            goto fail;
+        }
         /* TODO: register cpu for reset & update F/W info for the next boot */
     }
 
     cs->disabled = false;
     return;
+fail:
+    error_propagate(errp, local_err);
 }
 
 static void virt_cpu_unplug_request(HotplugHandler *hotplug_dev,
@@ -3182,8 +3191,10 @@ 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!");
@@ -3202,9 +3213,16 @@ static void virt_cpu_unplug_request(HotplugHandler 
*hotplug_dev,
         return;
     }
 
-    /* TODO: request cpu hotplug from guest */
+    /* 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) {
+        goto fail;
+    }
 
     return;
+fail:
+    error_propagate(errp, local_err);
 }
 
 static void virt_cpu_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
@@ -3212,7 +3230,9 @@ 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) {
@@ -3222,7 +3242,12 @@ 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) {
+        goto fail;
+    }
 
     unwire_gic_cpu_irqs(vms, cs);
     virt_update_gic(vms, cs);
@@ -3236,6 +3261,8 @@ static void virt_cpu_unplug(HotplugHandler *hotplug_dev, 
DeviceState *dev,
     cs->disabled = true;
 
     return;
+fail:
+    error_propagate(errp, local_err);
 }
 
 static void virt_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
-- 
2.34.1