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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3035f3a0-5d0f-49e7-88e5-1898a554dede@intel.com>
Date: Fri, 31 Oct 2025 09:03:57 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Sagi Shahar <sagis@...gle.com>, <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>, Binbin Wu <binbin.wu@...ux.intel.com>, "Oliver
 Upton" <oliver.upton@...ux.dev>, "Pratik R. Sampat"
	<pratikrajesh.sampat@....com>, Ira Weiny <ira.weiny@...el.com>, Chao Gao
	<chao.gao@...el.com>, Chenyi Qiang <chenyi.qiang@...el.com>
CC: <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>
Subject: Re: [PATCH v12 18/23] KVM: selftests: Set entry point for TDX guest
 code

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@...gle.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