linux-kernel - Re: [RFC 3/5] selftests: KVM: SEV IOCTL test

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Message-ID: <8870ca39-f5a9-8d33-3372-77a6693ad739@amd.com>
Date: Thu, 11 Jul 2024 13:34:01 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: "Pratik R. Sampat" <pratikrajesh.sampat@....com>, kvm@...r.kernel.org
Cc: shuah@...nel.org, michael.roth@....com, seanjc@...gle.com,
 pbonzini@...hat.com, pgonda@...gle.com, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [RFC 3/5] selftests: KVM: SEV IOCTL test

On 7/10/24 17:05, Pratik R. Sampat wrote:
> Introduce tests for sev and sev-es ioctl that exercises the boot path
> of launch, update and finish on an invalid policy.
> 
> Signed-off-by: Pratik R. Sampat <pratikrajesh.sampat@....com>
> ---
>  .../selftests/kvm/x86_64/sev_smoke_test.c     | 57 +++++++++++++++++++
>  1 file changed, 57 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c
> index 1a50a280173c..500c67b3793b 100644
> --- a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c
> @@ -131,12 +131,69 @@ static void test_sync_vmsa(uint32_t type, uint32_t policy)
>  	kvm_vm_free(vm);
>  }
>  
> +static void sev_guest_status_assert(struct kvm_vm *vm, uint32_t type)
> +{
> +	struct kvm_sev_guest_status status;
> +	bool cond;
> +	int ret;
> +
> +	ret = __vm_sev_ioctl(vm, KVM_SEV_GUEST_STATUS, &status);
> +	cond = type == KVM_X86_SEV_VM ? !ret : ret;
> +	TEST_ASSERT(cond,
> +		    "KVM_SEV_GUEST_STATUS should fail, invalid VM Type.");
> +}
> +
> +static void test_sev_launch(void *guest_code, uint32_t type, uint64_t policy)
> +{
> +	struct kvm_vcpu *vcpu;
> +	struct kvm_vm *vm;
> +	struct ucall uc;
> +	bool cond;
> +	int ret;
> +

Maybe a block comment here indicating what you're actually doing would
be good, because I'm a bit confused.

A policy value of 0 is valid for SEV, so you expect each call to
succeed, right? And, actually, for SEV-ES the launch start will succeed,
too, but the launch update will fail because LAUNCH_UPDATE_VMSA is not
valid for SEV, but then the launch measure should succeed. Is that
right? What about the other calls?

Thanks,
Tom

> +	vm = vm_sev_create_with_one_vcpu(type, guest_code, &vcpu);
> +	ret = sev_vm_launch_start(vm, 0);
> +	cond = type == KVM_X86_SEV_VM ? !ret : ret;
> +	TEST_ASSERT(cond,
> +		    "KVM_SEV_LAUNCH_START should fail, invalid policy.");
> +
> +	ret = sev_vm_launch_update(vm, policy);
> +	cond = type == KVM_X86_SEV_VM ? !ret : ret;
> +	TEST_ASSERT(cond,
> +		    "KVM_SEV_LAUNCH_UPDATE should fail, invalid policy.");
> +	sev_guest_status_assert(vm, type);
> +
> +	ret = sev_vm_launch_measure(vm, alloca(256));
> +	cond = type == KVM_X86_SEV_VM ? !ret : ret;
> +	TEST_ASSERT(cond,
> +		    "KVM_SEV_LAUNCH_MEASURE should fail, invalid policy.");
> +	sev_guest_status_assert(vm, type);
> +
> +	ret = sev_vm_launch_finish(vm);
> +	cond = type == KVM_X86_SEV_VM ? !ret : ret;
> +	TEST_ASSERT(cond,
> +		    "KVM_SEV_LAUNCH_FINISH should fail, invalid policy.");
> +	sev_guest_status_assert(vm, type);
> +
> +	vcpu_run(vcpu);
> +	get_ucall(vcpu, &uc);
> +	cond = type == KVM_X86_SEV_VM ?
> +		vcpu->run->exit_reason == KVM_EXIT_IO :
> +		vcpu->run->exit_reason == KVM_EXIT_FAIL_ENTRY;
> +	TEST_ASSERT(cond,
> +		    "vcpu_run should fail, invalid policy.");
> +
> +	kvm_vm_free(vm);
> +}
> +
>  static void test_sev(void *guest_code, uint32_t type, uint64_t policy)
>  {
>  	struct kvm_vcpu *vcpu;
>  	struct kvm_vm *vm;
>  	struct ucall uc;
>  
> +	test_sev_launch(guest_code, type, policy);
> +
>  	vm = vm_sev_create_with_one_vcpu(type, guest_code, &vcpu);
>  
>  	/* TODO: Validate the measurement is as expected. */