Re: [PATCH 3/4] target/i386: allow reordering max_x86_cpu_initfn vs accel CPU init

[Xiaoyao Li]

On 7/11/2025 8:06 AM, Paolo Bonzini wrote:

The PMU feature is only supported by KVM, so move it there.  And since
all accelerators other than TCG overwrite the vendor, set it in
max_x86_cpu_initfn only if it has not been initialized by the
superclass.  This makes it possible to run max_x86_cpu_initfn
after accelerator init.

Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>

Reviewed-by: Xiaoyao Li <xiaoyao...@intel.com>

---
  target/i386/cpu.c         | 24 ++++++++++++------------
  target/i386/kvm/kvm-cpu.c |  2 ++
  2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 69bdffbfe46..46d59229200 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6204,21 +6204,21 @@ static void max_x86_cpu_class_init(ObjectClass *oc, 
const void *data)
  static void max_x86_cpu_initfn(Object *obj)
  {
      X86CPU *cpu = X86_CPU(obj);
-
-    /* We can't fill the features array here because we don't know yet if
-     * "migratable" is true or false.
-     */
-    object_property_set_bool(OBJECT(cpu), "pmu", true, &error_abort);
+    CPUX86State *env = &cpu->env;

/*

-     * these defaults are used for TCG and all other accelerators
-     * besides KVM and HVF, which overwrite these values
+     * these defaults are used for TCG, other accelerators overwrite these
+     * values
       */
-    object_property_set_str(OBJECT(cpu), "vendor", CPUID_VENDOR_AMD,
-                            &error_abort);
-    object_property_set_str(OBJECT(cpu), "model-id",
-                            "QEMU TCG CPU version " QEMU_HW_VERSION,
-                            &error_abort);
+    if (!env->cpuid_vendor1) {
+        object_property_set_str(OBJECT(cpu), "vendor", CPUID_VENDOR_AMD,
+                                &error_abort);
+    }
+    if (!env->cpuid_model[0]) {
+        object_property_set_str(OBJECT(cpu), "model-id",
+                                "QEMU TCG CPU version " QEMU_HW_VERSION,
+                                &error_abort);
+    }
  }

static const TypeInfo max_x86_cpu_type_info = {

diff --git a/target/i386/kvm/kvm-cpu.c b/target/i386/kvm/kvm-cpu.c
index 0fb88a239d4..6fed353548e 100644
--- a/target/i386/kvm/kvm-cpu.c
+++ b/target/i386/kvm/kvm-cpu.c
@@ -111,6 +111,8 @@ static void kvm_cpu_max_instance_init(X86CPU *cpu)

host_cpu_max_instance_init(cpu); + object_property_set_bool(OBJECT(cpu), "pmu", true, &error_abort);

+
      if (lmce_supported()) {
          object_property_set_bool(OBJECT(cpu), "lmce", true, &error_abort);
      }