Re: [PATCH v12 17/23] KVM: selftests: Call KVM_TDX_INIT_VCPU when creating a new TDX vcpu

Binbin Wu
2025-10-30T06:15:08Z

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;