Re: [PATCH v7 10/16] i386/cpu: Introduce cluster-id to X86CPU

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On 1/8/2024 4:27 PM, Zhao Liu wrote:
From: Zhuocheng Ding <zhuocheng.ding@xxxxxxxxx>

Introduce cluster-id other than module-id to be consistent with
CpuInstanceProperties.cluster-id, and this avoids the confusion
of parameter names when hotplugging.

I don't think reusing 'cluster' from arm for x86's 'module' is a good idea. It introduces confusion around the code.

s390 just added 'drawer' and 'book' in cpu topology[1]. I think we can also add a module level for x86 instead of reusing cluster.

(This is also what I want to reply to the cover letter.)

[1] https://lore.kernel.org/qemu-devel/20231016183925.2384704-1-nsg@xxxxxxxxxxxxx/

Following the legacy smp check rules, also add the cluster_id validity
into x86_cpu_pre_plug().

Signed-off-by: Zhuocheng Ding <zhuocheng.ding@xxxxxxxxx>
Co-developed-by: Zhao Liu <zhao1.liu@xxxxxxxxx>
Signed-off-by: Zhao Liu <zhao1.liu@xxxxxxxxx>
Tested-by: Babu Moger <babu.moger@xxxxxxx>
Tested-by: Yongwei Ma <yongwei.ma@xxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
Changes since v6:
  * Update the comment when check cluster-id. Since there's no
    v8.2, the cluster-id support should at least start from v9.0.

Changes since v5:
  * Update the comment when check cluster-id. Since current QEMU is
    v8.2, the cluster-id support should at least start from v8.3.

Changes since v3:
  * Use the imperative in the commit message. (Babu)
---
  hw/i386/x86.c     | 33 +++++++++++++++++++++++++--------
  target/i386/cpu.c |  2 ++
  target/i386/cpu.h |  1 +
  3 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/hw/i386/x86.c b/hw/i386/x86.c
index 5269aae3a5c2..1c1d368614ee 100644
--- a/hw/i386/x86.c
+++ b/hw/i386/x86.c
@@ -329,6 +329,14 @@ void x86_cpu_pre_plug(HotplugHandler *hotplug_dev,
              cpu->die_id = 0;
          }
+ /*
+         * cluster-id was optional in QEMU 9.0 and older, so keep it optional
+         * if there's only one cluster per die.
+         */
+        if (cpu->cluster_id < 0 && ms->smp.clusters == 1) {
+            cpu->cluster_id = 0;
+        }
+
          if (cpu->socket_id < 0) {
              error_setg(errp, "CPU socket-id is not set");
              return;
@@ -345,6 +353,14 @@ void x86_cpu_pre_plug(HotplugHandler *hotplug_dev,
                         cpu->die_id, ms->smp.dies - 1);
              return;
          }
+        if (cpu->cluster_id < 0) {
+            error_setg(errp, "CPU cluster-id is not set");
+            return;
+        } else if (cpu->cluster_id > ms->smp.clusters - 1) {
+            error_setg(errp, "Invalid CPU cluster-id: %u must be in range 0:%u",
+                       cpu->cluster_id, ms->smp.clusters - 1);
+            return;
+        }
          if (cpu->core_id < 0) {
              error_setg(errp, "CPU core-id is not set");
              return;
@@ -364,16 +380,9 @@ void x86_cpu_pre_plug(HotplugHandler *hotplug_dev,
topo_ids.pkg_id = cpu->socket_id;
          topo_ids.die_id = cpu->die_id;
+        topo_ids.module_id = cpu->cluster_id;
          topo_ids.core_id = cpu->core_id;
          topo_ids.smt_id = cpu->thread_id;
-
-        /*
-         * TODO: This is the temporary initialization for topo_ids.module_id to
-         * avoid "maybe-uninitialized" compilation errors. Will remove when
-         * X86CPU supports cluster_id.
-         */
-        topo_ids.module_id = 0;
-
          cpu->apic_id = x86_apicid_from_topo_ids(&topo_info, &topo_ids);
      }
@@ -418,6 +427,14 @@ void x86_cpu_pre_plug(HotplugHandler *hotplug_dev,
      }
      cpu->die_id = topo_ids.die_id;
+ if (cpu->cluster_id != -1 && cpu->cluster_id != topo_ids.module_id) {
+        error_setg(errp, "property cluster-id: %u doesn't match set apic-id:"
+            " 0x%x (cluster-id: %u)", cpu->cluster_id, cpu->apic_id,
+            topo_ids.module_id);
+        return;
+    }
+    cpu->cluster_id = topo_ids.module_id;
+
      if (cpu->core_id != -1 && cpu->core_id != topo_ids.core_id) {
          error_setg(errp, "property core-id: %u doesn't match set apic-id:"
              " 0x%x (core-id: %u)", cpu->core_id, cpu->apic_id,
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index a2d39d2198b6..498a4be62b40 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -7909,12 +7909,14 @@ static Property x86_cpu_properties[] = {
      DEFINE_PROP_UINT32("apic-id", X86CPU, apic_id, 0),
      DEFINE_PROP_INT32("thread-id", X86CPU, thread_id, 0),
      DEFINE_PROP_INT32("core-id", X86CPU, core_id, 0),
+    DEFINE_PROP_INT32("cluster-id", X86CPU, cluster_id, 0),
      DEFINE_PROP_INT32("die-id", X86CPU, die_id, 0),
      DEFINE_PROP_INT32("socket-id", X86CPU, socket_id, 0),
  #else
      DEFINE_PROP_UINT32("apic-id", X86CPU, apic_id, UNASSIGNED_APIC_ID),
      DEFINE_PROP_INT32("thread-id", X86CPU, thread_id, -1),
      DEFINE_PROP_INT32("core-id", X86CPU, core_id, -1),
+    DEFINE_PROP_INT32("cluster-id", X86CPU, cluster_id, -1),
      DEFINE_PROP_INT32("die-id", X86CPU, die_id, -1),
      DEFINE_PROP_INT32("socket-id", X86CPU, socket_id, -1),
  #endif
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 97b290e10576..009950b87203 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -2057,6 +2057,7 @@ struct ArchCPU {
      int32_t node_id; /* NUMA node this CPU belongs to */
      int32_t socket_id;
      int32_t die_id;
+    int32_t cluster_id;
      int32_t core_id;
      int32_t thread_id;





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