[v12] TDX KVM selftests

[PATCH v12 18/23] KVM: selftests: Set entry point for TDX guest code

Posted by Sagi Shahar 1 month, 2 weeks ago

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>
---
 tools/testing/selftests/kvm/lib/x86/processor.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index 036875fe140f..17f5a381fe43 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -691,9 +691,13 @@ 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))
+		vm_tdx_set_vcpu_entry_point(vcpu, guest_code);
+	else {
+		vcpu_regs_get(vcpu, &regs);
+		regs.rip = (unsigned long) guest_code;
+		vcpu_regs_set(vcpu, &regs);
+	}
 }
 
 vm_vaddr_t kvm_allocate_vcpu_stack(struct kvm_vm *vm)
-- 
2.51.1.851.g4ebd6896fd-goog

Re: [PATCH v12 18/23] KVM: selftests: Set entry point for TDX guest code

Posted by Reinette Chatre 1 month, 2 weeks ago

Hi Sagi,

On 10/28/25 2:20 PM, Sagi Shahar wrote:
> 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.

Check the changelog for code impersonation, imperative tone, and matching the
KVM requirements.

> 
> Signed-off-by: Sagi Shahar <sagis@google.com>
> ---
>  tools/testing/selftests/kvm/lib/x86/processor.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
> index 036875fe140f..17f5a381fe43 100644
> --- a/tools/testing/selftests/kvm/lib/x86/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86/processor.c
> @@ -691,9 +691,13 @@ 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))
> +		vm_tdx_set_vcpu_entry_point(vcpu, guest_code);

Please use braces around both branches. (for reference
"Placing Braces and Spaces" in Documentation/process/coding-style.rst)

> +	else {
> +		vcpu_regs_get(vcpu, &regs);
> +		regs.rip = (unsigned long) guest_code;

You can drop the space after the cast above.

> +		vcpu_regs_set(vcpu, &regs);
> +	}
>  }
>  
>  vm_vaddr_t kvm_allocate_vcpu_stack(struct kvm_vm *vm)

Reinette