Re: [PATCH] KVM: selftests: Skip tests that require EPT when it is not available

[Sean Christopherson <seanjc@google.com>]

On Mon, Sep 26, 2022, David Matlack wrote:
> +bool kvm_vm_has_ept(struct kvm_vm *vm)
> +{
> +	struct kvm_vcpu *vcpu;
> +	uint64_t ctrl;
> +
> +	vcpu = list_first_entry(&vm->vcpus, struct kvm_vcpu, list);
> +	TEST_ASSERT(vcpu, "Cannot determine EPT support without vCPUs.\n");

KVM_GET_MSRS is supported on /dev/kvm for feature MSRs, and is available for
selftests via kvm_get_feature_msr().

> +
> +	ctrl = vcpu_get_msr(vcpu, MSR_IA32_VMX_TRUE_PROCBASED_CTLS) >> 32;
> +	if (!(ctrl & CPU_BASED_ACTIVATE_SECONDARY_CONTROLS))
> +		return false;
> +
> +	ctrl = vcpu_get_msr(vcpu, MSR_IA32_VMX_PROCBASED_CTLS2) >> 32;
> +	return ctrl & SECONDARY_EXEC_ENABLE_EPT;
> +}
> +
>  void prepare_eptp(struct vmx_pages *vmx, struct kvm_vm *vm,
>  		  uint32_t eptp_memslot)
>  {
> +	TEST_REQUIRE(kvm_vm_has_ept(vm));

I would much rather this be an assert, i.e. force the test to do TEST_REQUIRE(),
even if that means duplicate code.  One of the roles of TEST_REQUIRE() is to
document test requirements.