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

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Message-ID: <98c1f8e2-3b24-49c4-b5fc-506e4283248d@amd.com>
Date: Thu, 11 Jul 2024 15:02:52 -0500
From: "Sampat, Pratik Rajesh" <pratikrajesh.sampat@....com>
To: Tom Lendacky <thomas.lendacky@....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

Hi Tom

On 7/11/2024 1:34 PM, Tom Lendacky wrote:
> 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?
> 

Sure, I can do that.
Yes for SEV, the policy value of 0 succeeds for everything except when
we try to run and we see a KVM_EXIT_IO.

For SEV-ES, with the policy value of 0 - we don't see launch_start
succeed. It fails with EIO in this case. Post that all the calls for
SEV-ES also fail subsequent to that. I guess the core idea behind this
test is to ensure that once the first bad case of launch_start fails, we
should see a cascading list of failures.

Thank you!
Pratik

> 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. */