Re: [PATCH v14 17/22] KVM: selftests: Set entry point for TDX guest code

[Xiaoyao Li <xiaoyao.li@intel.com>]

On 7/23/2026 7:13 AM, Lisa Wang wrote:
> From: Sagi Shahar <sagis@google.com>
> 
> Since the rip register is inaccessible for TDX VMs, we need a different
> way to set the guest entry point for TDX VMs. This is done by writing
> the guest code address to a predefined location in the guest memory and
> loading it into rip as part of the TDX boot code.
> 
> Signed-off-by: Sagi Shahar <sagis@google.com>
> Signed-off-by: Lisa Wang <wyihan@google.com>

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

> ---
>   tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h |  1 +
>   tools/testing/selftests/kvm/lib/x86/processor.c        | 10 +++++++---
>   tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c     | 10 ++++++++++
>   3 files changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
> index 93ce6e1ad2c8..307e2c0bc9c9 100644
> --- a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
> +++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
> @@ -70,5 +70,6 @@ void tdx_vm_setup_boot_code_region(struct kvm_vm *vm);
>   void tdx_vm_setup_boot_parameters_region(struct kvm_vm *vm, u32 nr_runnable_vcpus);
>   void tdx_vm_load_common_boot_parameters(struct kvm_vm *vm);
>   void tdx_vcpu_load_boot_parameters(struct kvm_vm *vm, struct kvm_vcpu *vcpu);
> +void tdx_vcpu_set_entry_point(struct kvm_vcpu *vcpu, void *guest_code);
>   
>   #endif /* SELFTESTS_TDX_TDX_UTIL_H */
> diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
> index 5e415c6577b8..4b97a9a1bb5e 100644
> --- a/tools/testing/selftests/kvm/lib/x86/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86/processor.c
> @@ -808,9 +808,13 @@ void vcpu_arch_set_entry_point(struct kvm_vcpu *vcpu, void *guest_code)
>   {
>   	struct kvm_regs regs;
>   
> -	vcpu_regs_get(vcpu, &regs);
> -	regs.rip = (unsigned long) guest_code;
> -	vcpu_regs_set(vcpu, &regs);
> +	if (is_tdx_vm(vcpu->vm)) {
> +		tdx_vcpu_set_entry_point(vcpu, guest_code);
> +	} else {
> +		vcpu_regs_get(vcpu, &regs);
> +		regs.rip = (unsigned long)guest_code;
> +		vcpu_regs_set(vcpu, &regs);
> +	}
>   }
>   
>   gva_t kvm_allocate_vcpu_stack(struct kvm_vm *vm)
> diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> index 3c3ac6c7ce40..be63d8652a02 100644
> --- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> @@ -114,6 +114,16 @@ void tdx_vcpu_load_boot_parameters(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
>   	vcpu_params->esp_gva = kvm_allocate_vcpu_stack(vm);
>   }
>   
> +void tdx_vcpu_set_entry_point(struct kvm_vcpu *vcpu, void *guest_code)
> +{
> +	struct td_boot_parameters *params =
> +		addr_gpa2hva(vcpu->vm, TD_BOOT_PARAMETERS_GPA);
> +	struct td_per_vcpu_parameters *vcpu_params =
> +		&params->per_vcpu[vcpu->id];
> +
> +	vcpu_params->guest_code = (u64)guest_code;
> +}
> +
>   static struct kvm_tdx_capabilities *tdx_read_capabilities(struct kvm_vm *vm)
>   {
>   	static struct kvm_tdx_capabilities *tdx_cap;
>