linux-kernel - Re: [PATCH v12 17/23] KVM: selftests: Call KVM_TDX_INIT

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Message-ID: <f55516ea-b8de-4d77-a2c5-dffef2f66d7c@linux.intel.com>
Date: Thu, 30 Oct 2025 14:15:01 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Sagi Shahar <sagis@...gle.com>
Cc: linux-kselftest@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
 Shuah Khan <shuah@...nel.org>, Sean Christopherson <seanjc@...gle.com>,
 Ackerley Tng <ackerleytng@...gle.com>, Ryan Afranji <afranji@...gle.com>,
 Andrew Jones <ajones@...tanamicro.com>,
 Isaku Yamahata <isaku.yamahata@...el.com>,
 Erdem Aktas <erdemaktas@...gle.com>,
 Rick Edgecombe <rick.p.edgecombe@...el.com>,
 Roger Wang <runanwang@...gle.com>, Oliver Upton <oliver.upton@...ux.dev>,
 "Pratik R. Sampat" <pratikrajesh.sampat@....com>,
 Reinette Chatre <reinette.chatre@...el.com>, Ira Weiny
 <ira.weiny@...el.com>, Chao Gao <chao.gao@...el.com>,
 Chenyi Qiang <chenyi.qiang@...el.com>, linux-kernel@...r.kernel.org,
 kvm@...r.kernel.org
Subject: Re: [PATCH v12 17/23] KVM: selftests: Call KVM_TDX_INIT_VCPU when
 creating a new TDX vcpu



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@...gle.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;