i386/tdx: Error and exit when named cpu model is requested

Currently, it gets below error when requesting any named cpu model with
"-cpu" to boot a TDX VM:

  qemu-system-x86_64: KVM_TDX_INIT_VM failed: Invalid argument

It misleads people to think it's the bug of KVM or QEMU. It is just that
current QEMU doesn't support named cpu model for TDX.

To support named cpu models for TDX guest, there are opens to be
finalized and needs a mount of additional work.

For now, explicitly check the case when named cpu model is requested.
Error report a hint and exit.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20250612133801.2238342-1-xiaoyao.li@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index 820ca3614e27b022b3e97736db7f7b1765f211f2..2b52de9d71bcd85ad5933bcdce3104424134ed60 100644 (file)
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -739,8 +739,14 @@ static int tdx_kvm_type(X86ConfidentialGuest *cg)
 
 static void tdx_cpu_instance_init(X86ConfidentialGuest *cg, CPUState *cpu)
 {
+    X86CPUClass *xcc = X86_CPU_GET_CLASS(cpu);
     X86CPU *x86cpu = X86_CPU(cpu);
 
+    if (xcc->model) {
+        error_report("Named cpu model is not supported for TDX yet!");
+        exit(1);
+    }
+
     object_property_set_bool(OBJECT(cpu), "pmu", false, &error_abort);
 
     /* invtsc is fixed1 for TD guest */