[Qemu-devel] [RFC v3 8/8] hw/arm/virt: Add virt-3.0 machine type supporting up to 512 vcpus

[Eric Auger <eric.auger@redhat.com>]

Add virt-3.0 machine type.

This machine type allows up to 512 vcpus whereas for
earlier machine types, max_cpus was set to 255 and
any attempt to start the machine with vcpus > 255
was rejected at vl.c/main level.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 hw/arm/virt.c | 32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index c00f47d..a9fc24b 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1697,11 +1697,13 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
     HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc);
 
     mc->init = machvirt_init;
-    /* Start max_cpus at the maximum QEMU supports. We'll further restrict
-     * it later in machvirt_init, where we have more information about the
-     * configuration of the particular instance.
+    /* Start with max_cpus set to 512. This value is chosen since achievable
+     * in accelerated mode with GICv3 and recent host supporting up to 512 vcpus
+     * and multiple redistributor region registration.
+     * This value will be refined later on once we collect more information
+     * about the configuration of the particular instance.
      */
-    mc->max_cpus = 255;
+    mc->max_cpus = 512;
     machine_class_allow_dynamic_sysbus_dev(mc, TYPE_VFIO_CALXEDA_XGMAC);
     machine_class_allow_dynamic_sysbus_dev(mc, TYPE_VFIO_AMD_XGBE);
     mc->block_default_type = IF_VIRTIO;
@@ -1737,7 +1739,7 @@ static void machvirt_machine_init(void)
 }
 type_init(machvirt_machine_init);
 
-static void virt_2_12_instance_init(Object *obj)
+static void virt_3_0_instance_init(Object *obj)
 {
     VirtMachineState *vms = VIRT_MACHINE(obj);
     VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(vms);
@@ -1805,10 +1807,26 @@ static void virt_2_12_instance_init(Object *obj)
     vms->irqmap = a15irqmap;
 }
 
-static void virt_machine_2_12_options(MachineClass *mc)
+static void virt_machine_3_0_options(MachineClass *mc)
 {
 }
-DEFINE_VIRT_MACHINE_AS_LATEST(2, 12)
+DEFINE_VIRT_MACHINE_AS_LATEST(3, 0)
+
+#define VIRT_COMPAT_2_12 \
+    HW_COMPAT_2_12
+
+static void virt_2_12_instance_init(Object *obj)
+{
+    virt_3_0_instance_init(obj);
+}
+
+static void virt_machine_2_12_options(MachineClass *mc)
+{
+    virt_machine_3_0_options(mc);
+    SET_MACHINE_COMPAT(mc, VIRT_COMPAT_2_12);
+    mc->max_cpus = 255;
+}
+DEFINE_VIRT_MACHINE(2, 12)
 
 #define VIRT_COMPAT_2_11 \
     HW_COMPAT_2_11
-- 
2.5.5