TDX VMs need to issue the KVM_TDX_INIT_VCPU ioctl for each vcpu after
vcpu creation.

Since the cpuids for TD are managed by the TDX module, read the values
virtualized for the TD using KVM_TDX_GET_CPUID and set them in kvm using
KVM_SET_CPUID2 so that kvm has an accurate view of the VM cpuid values.

Signed-off-by: Sagi Shahar <sagis@google.com>
---
 .../testing/selftests/kvm/lib/x86/processor.c | 35 ++++++++++++++-----
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index 990f2769c5d8..036875fe140f 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -722,6 +722,19 @@ vm_vaddr_t kvm_allocate_vcpu_stack(struct kvm_vm *vm)
 	return stack_vaddr;
 }
 
+static void vm_tdx_vcpu_add(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
+{
+	struct kvm_cpuid2 *cpuid;
+
+	cpuid = allocate_kvm_cpuid2(MAX_NR_CPUID_ENTRIES);
+	vm_tdx_vcpu_ioctl(vcpu, KVM_TDX_GET_CPUID, 0, cpuid);
+	vcpu_init_cpuid(vcpu, cpuid);
+	free(cpuid);
+	vm_tdx_vcpu_ioctl(vcpu, KVM_TDX_INIT_VCPU, 0, NULL);
+
+	vm_tdx_load_vcpu_boot_parameters(vm, vcpu);
+}
+
 struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
 {
 	struct kvm_mp_state mp_state;
@@ -729,15 +742,21 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
 	struct kvm_vcpu *vcpu;
 
 	vcpu = __vm_vcpu_add(vm, vcpu_id);
-	vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
-	vcpu_init_sregs(vm, vcpu);
-	vcpu_init_xcrs(vm, vcpu);
 
-	/* Setup guest general purpose registers */
-	vcpu_regs_get(vcpu, &regs);
-	regs.rflags = regs.rflags | 0x2;
-	regs.rsp = kvm_allocate_vcpu_stack(vm);
-	vcpu_regs_set(vcpu, &regs);
+	if (is_tdx_vm(vm)) {
+		vm_tdx_vcpu_add(vm, vcpu);
+	} else {
+		vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
+
+		vcpu_init_sregs(vm, vcpu);
+		vcpu_init_xcrs(vm, vcpu);
+
+		/* Setup guest general purpose registers */
+		vcpu_regs_get(vcpu, &regs);
+		regs.rflags = regs.rflags | 0x2;
+		regs.rsp = kvm_allocate_vcpu_stack(vm);
+		vcpu_regs_set(vcpu, &regs);
+	}
 
 	/* Setup the MP state */
 	mp_state.mp_state = 0;
-- 
2.51.1.851.g4ebd6896fd-goog

On 10/29/2025 5:20 AM, Sagi Shahar wrote:
> TDX VMs need to issue the KVM_TDX_INIT_VCPU ioctl for each vcpu after
> vcpu creation.
>
> Since the cpuids for TD are managed by the TDX module, read the values
> virtualized for the TD using KVM_TDX_GET_CPUID and set them in kvm using
> KVM_SET_CPUID2 so that kvm has an accurate view of the VM cpuid values.
>
> Signed-off-by: Sagi Shahar <sagis@google.com>
> ---
>   .../testing/selftests/kvm/lib/x86/processor.c | 35 ++++++++++++++-----
>   1 file changed, 27 insertions(+), 8 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
> index 990f2769c5d8..036875fe140f 100644
> --- a/tools/testing/selftests/kvm/lib/x86/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86/processor.c
> @@ -722,6 +722,19 @@ vm_vaddr_t kvm_allocate_vcpu_stack(struct kvm_vm *vm)
>   	return stack_vaddr;
>   }
>   
> +static void vm_tdx_vcpu_add(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
> +{
> +	struct kvm_cpuid2 *cpuid;
> +
> +	cpuid = allocate_kvm_cpuid2(MAX_NR_CPUID_ENTRIES);
> +	vm_tdx_vcpu_ioctl(vcpu, KVM_TDX_GET_CPUID, 0, cpuid);
> +	vcpu_init_cpuid(vcpu, cpuid);
> +	free(cpuid);
> +	vm_tdx_vcpu_ioctl(vcpu, KVM_TDX_INIT_VCPU, 0, NULL);
> +
> +	vm_tdx_load_vcpu_boot_parameters(vm, vcpu);
> +}
> +
>   struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
>   {
>   	struct kvm_mp_state mp_state;
> @@ -729,15 +742,21 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
>   	struct kvm_vcpu *vcpu;
>   
>   	vcpu = __vm_vcpu_add(vm, vcpu_id);
> -	vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
> -	vcpu_init_sregs(vm, vcpu);
> -	vcpu_init_xcrs(vm, vcpu);
>   
> -	/* Setup guest general purpose registers */
> -	vcpu_regs_get(vcpu, &regs);
> -	regs.rflags = regs.rflags | 0x2;
> -	regs.rsp = kvm_allocate_vcpu_stack(vm);
> -	vcpu_regs_set(vcpu, &regs);
> +	if (is_tdx_vm(vm)) {
> +		vm_tdx_vcpu_add(vm, vcpu);
Nit:
Since vcpu is added by  __vm_vcpu_add() above, using 'init' instead of 'add' in
the function name makes it more clear.

> +	} else {
> +		vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
> +
> +		vcpu_init_sregs(vm, vcpu);
> +		vcpu_init_xcrs(vm, vcpu);
> +
> +		/* Setup guest general purpose registers */
> +		vcpu_regs_get(vcpu, &regs);
> +		regs.rflags = regs.rflags | 0x2;
> +		regs.rsp = kvm_allocate_vcpu_stack(vm);
> +		vcpu_regs_set(vcpu, &regs);
> +	}
>   
>   	/* Setup the MP state */
>   	mp_state.mp_state = 0;