machine: introduce MachineClass.possible_cpu_arch_ids() hook

on x86 currently range 0..max_cpus is used to generate
architecture-dependent CPU ID (APIC Id) for each present
and possible CPUs. However architecture-dependent CPU IDs
list could be sparse and code that needs to enumerate
all IDs (ACPI) ended up doing guess work enumerating all
possible and impossible IDs up to
  apic_id_limit = x86_cpu_apic_id_from_index(max_cpus).

That leads to creation of MADT entries and Processor
objects in ACPI tables for not possible CPUs.
Fix it by allowing board specify a concrete list of
CPU IDs accourding its own rules (which for x86 depends
on topology). So that code that needs this list could
request it from board instead of trying to guess
what IDs are correct on its own.

This interface will also allow to help making AML
part of CPU hotplug target independent so it could
be reused for ARM target.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>

1 files changed, 40 insertions, 4 deletions

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index a469979f4a..2ac97c4f29 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1131,10 +1131,17 @@ void pc_cpus_init(PCMachineState *pcms)
         exit(1);
     }
 
-    for (i = 0; i < smp_cpus; i++) {
-        cpu = pc_new_cpu(machine->cpu_model, x86_cpu_apic_id_from_index(i),
-                         &error_fatal);
-        object_unref(OBJECT(cpu));
+    pcms->possible_cpus = g_malloc0(sizeof(CPUArchIdList) +
+                                    sizeof(CPUArchId) * max_cpus);
+    for (i = 0; i < max_cpus; i++) {
+        pcms->possible_cpus->cpus[i].arch_id = x86_cpu_apic_id_from_index(i);
+        pcms->possible_cpus->len++;
+        if (i < smp_cpus) {
+            cpu = pc_new_cpu(machine->cpu_model, x86_cpu_apic_id_from_index(i),
+                             &error_fatal);
+            pcms->possible_cpus->cpus[i].cpu = CPU(cpu);
+            object_unref(OBJECT(cpu));
+        }
     }
 
     /* tell smbios about cpuid version and features */
@@ -1657,9 +1664,19 @@ static void pc_dimm_unplug(HotplugHandler *hotplug_dev,
     error_propagate(errp, local_err);
 }
 
+static int pc_apic_cmp(const void *a, const void *b)
+{
+   CPUArchId *apic_a = (CPUArchId *)a;
+   CPUArchId *apic_b = (CPUArchId *)b;
+
+   return apic_a->arch_id - apic_b->arch_id;
+}
+
 static void pc_cpu_plug(HotplugHandler *hotplug_dev,
                         DeviceState *dev, Error **errp)
 {
+    CPUClass *cc = CPU_GET_CLASS(dev);
+    CPUArchId apic_id, *found_cpu;
     HotplugHandlerClass *hhc;
     Error *local_err = NULL;
     PCMachineState *pcms = PC_MACHINE(hotplug_dev);
@@ -1682,6 +1699,13 @@ static void pc_cpu_plug(HotplugHandler *hotplug_dev,
 
     /* increment the number of CPUs */
     rtc_set_memory(pcms->rtc, 0x5f, rtc_get_memory(pcms->rtc, 0x5f) + 1);
+
+    apic_id.arch_id = cc->get_arch_id(CPU(dev));
+    found_cpu = bsearch(&apic_id, pcms->possible_cpus->cpus,
+        pcms->possible_cpus->len, sizeof(*pcms->possible_cpus->cpus),
+        pc_apic_cmp);
+    assert(found_cpu);
+    found_cpu->cpu = CPU(dev);
 out:
     error_propagate(errp, local_err);
 }
@@ -1924,6 +1948,17 @@ static unsigned pc_cpu_index_to_socket_id(unsigned cpu_index)
     return topo.pkg_id;
 }
 
+static CPUArchIdList *pc_possible_cpu_arch_ids(MachineState *machine)
+{
+    PCMachineState *pcms = PC_MACHINE(machine);
+    int len = sizeof(CPUArchIdList) +
+              sizeof(CPUArchId) * (pcms->possible_cpus->len);
+    CPUArchIdList *list = g_malloc(len);
+
+    memcpy(list, pcms->possible_cpus, len);
+    return list;
+}
+
 static void pc_machine_class_init(ObjectClass *oc, void *data)
 {
     MachineClass *mc = MACHINE_CLASS(oc);
@@ -1946,6 +1981,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     pcmc->save_tsc_khz = true;
     mc->get_hotplug_handler = pc_get_hotpug_handler;
     mc->cpu_index_to_socket_id = pc_cpu_index_to_socket_id;
+    mc->possible_cpu_arch_ids = pc_possible_cpu_arch_ids;
     mc->default_boot_order = "cad";
     mc->hot_add_cpu = pc_hot_add_cpu;
     mc->max_cpus = 255;