[PATCH RFC 01/22] arm/cpuhp: Add QMP vcpu params validation support

[Salil Mehta <salil.mehta@huawei.com>]

For now, vcpu hotplug is only supported with single socket single thread,
single die. NUMA is not supported either and everthing falls into single
node. Work to properly support these could be taken later once community
agrees with the base framework changes being presented to support ARM vcpu
hotplug in QEMU. Hence, these checks.

Co-developed-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
---
 hw/arm/virt.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 37462a6f78..5d1afdd031 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2201,6 +2201,46 @@ static HotplugHandler *virt_machine_get_hotplug_handler(MachineState *machine,
     return NULL;
 }
 
+static void virt_smp_parse(MachineState *ms, QemuOpts *opts)
+{
+    if (opts) {
+        unsigned cpus    = qemu_opt_get_number(opts, "cpus", 1);
+        unsigned sockets = qemu_opt_get_number(opts, "sockets", 1);
+        unsigned cores   = qemu_opt_get_number(opts, "cores", cpus);
+        unsigned threads = qemu_opt_get_number(opts, "threads", 1);
+        unsigned int max_cpus;
+
+        if (sockets > 1 || threads > 1) {
+            error_report("does not support more than one socket or thread");
+            exit(1);
+        }
+
+        if (cores != cpus) {
+            error_report("cpu topology: "
+                         "sockets (%u) * cores (%u) * threads (%u) < "
+                         "smp_cpus (%u)",
+                         sockets, cores, threads, cpus);
+            exit(1);
+        }
+
+        max_cpus = qemu_opt_get_number(opts, "maxcpus", cpus);
+        if (sockets * cores * threads > max_cpus) {
+            error_report("cpu topology: "
+                         "sockets (%u) * cores (%u) * threads (%u) > "
+                         "maxcpus (%u)",
+                         sockets, cores, threads,
+                         max_cpus);
+            exit(1);
+        }
+
+        ms->smp.max_cpus = max_cpus;
+        ms->smp.sockets = sockets;
+        ms->smp.cpus = cpus;
+        ms->smp.cores = cores;
+        ms->smp.threads = threads;
+    }
+}
+
 /*
  * for arm64 kvm_type [7-0] encodes the requested number of bits
  * in the IPA address space
@@ -2266,6 +2306,7 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
     mc->nvdimm_supported = true;
     mc->auto_enable_numa_with_memhp = true;
     mc->default_ram_id = "mach-virt.ram";
+    mc->smp_parse = virt_smp_parse;
 
     object_class_property_add(oc, "acpi", "OnOffAuto",
         virt_get_acpi, virt_set_acpi,
-- 
2.17.1