[PATCH RFC 02/22] arm/cpuhp: Add new ARMCPU core-id property

[Salil Mehta]

This shall be used to store user specified core index and shall be directly
used as slot-index during hot{plug|unplug} of vcpu.

For now, we are not taking into account of other topology info like thread-id,
socket-id to derive mp-affinity. Host KVM uses vcpu-id to derive the mpidr for
the vcpu of the guest. This is not in exact corroboration with the ARM spec
view of the MPIDR. Hence, the concept of threads or SMT bit present as part of
the MPIDR_EL1 also gets lost.

Also, we need ACPI PPTT Table support in QEMU to be able to export this
topology info to the guest VM and the info should be consistent with what host
cpu supports if accel=kvm is being used.

Perhaps some comments on this will help? @Andrew/drjones@redhat.com

Co-developed-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
---
 hw/arm/virt.c    | 5 +++++
 target/arm/cpu.c | 5 +++++
 target/arm/cpu.h | 1 +
 3 files changed, 11 insertions(+)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 5d1afdd031..c4ed955776 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1778,6 +1778,7 @@ static void machvirt_init(MachineState *machine)
                           &error_fatal);
 
         aarch64 &= object_property_get_bool(cpuobj, "aarch64", NULL);
+        object_property_set_int(cpuobj, n, "core-id", NULL);
 
         if (!vms->secure) {
             object_property_set_bool(cpuobj, false, "has_el3", NULL);
@@ -2081,6 +2082,7 @@ static const CPUArchIdList 
*virt_possible_cpu_arch_ids(MachineState *ms)
 {
     int n;
     unsigned int max_cpus = ms->smp.max_cpus;
+    unsigned int smp_threads = ms->smp.threads;
     VirtMachineState *vms = VIRT_MACHINE(ms);
 
     if (ms->possible_cpus) {
@@ -2093,8 +2095,11 @@ static const CPUArchIdList 
*virt_possible_cpu_arch_ids(MachineState *ms)
     ms->possible_cpus->len = max_cpus;
     for (n = 0; n < ms->possible_cpus->len; n++) {
         ms->possible_cpus->cpus[n].type = ms->cpu_type;
+        ms->possible_cpus->cpus[n].vcpus_count = smp_threads;
         ms->possible_cpus->cpus[n].arch_id =
             virt_cpu_mp_affinity(vms, n);
+        ms->possible_cpus->cpus[n].props.has_core_id = true;
+        ms->possible_cpus->cpus[n].props.core_id = n;
         ms->possible_cpus->cpus[n].props.has_thread_id = true;
         ms->possible_cpus->cpus[n].props.thread_id = n;
     }
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 32bec156f2..33a58086a9 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1086,6 +1086,9 @@ static Property arm_cpu_has_dsp_property =
 static Property arm_cpu_has_mpu_property =
             DEFINE_PROP_BOOL("has-mpu", ARMCPU, has_mpu, true);
 
+static Property arm_cpu_coreid_property =
+            DEFINE_PROP_INT32("core-id", ARMCPU, core_id, -1);
+
 /* This is like DEFINE_PROP_UINT32 but it doesn't set the default value,
  * because the CPU initfn will have already set cpu->pmsav7_dregion to
  * the right value for that particular CPU type, and we don't want
@@ -1168,6 +1171,8 @@ void arm_cpu_post_init(Object *obj)
         qdev_property_add_static(DEVICE(obj), &arm_cpu_rvbar_property);
     }
 
+    qdev_property_add_static(DEVICE(obj), &arm_cpu_coreid_property);
+
 #ifndef CONFIG_USER_ONLY
     if (arm_feature(&cpu->env, ARM_FEATURE_EL3)) {
         /* Add the has_el3 state CPU property only if EL3 is allowed.  This 
will
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 677584e5da..5c4991156e 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -949,6 +949,7 @@ struct ARMCPU {
     QLIST_HEAD(, ARMELChangeHook) el_change_hooks;
 
     int32_t node_id; /* NUMA node this CPU belongs to */
+    int32_t core_id; /* core-id of this ARM VCPU */
 
     /* Used to synchronize KVM and QEMU in-kernel device levels */
     uint8_t device_irq_level;
-- 
2.17.1