KVM: selftests: Add a macro to define a test with one vcpu

Most tests are currently not giving any proper output for the user
to see how much sub-tests have already been run, or whether new
sub-tests are part of a binary or not. So it would be good to
support TAP output in the KVM selftests. There is already a nice
framework for this in the kselftest_harness.h header which we can
use. But since we also need a vcpu in most KVM selftests, it also
makes sense to introduce our own wrapper around this which takes
care of creating a VM with one vcpu, so we don't have to repeat
this boilerplate in each and every test. Thus let's introduce
a KVM_ONE_VCPU_TEST() macro here which takes care of this.

Suggested-by: Sean Christopherson <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]/
Signed-off-by: Thomas Huth <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Sean Christopherson <[e-mail]>

tools/testing/selftests/kvm/include/kvm_test_harness.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Macros for defining a KVM test
+ *
+ * Copyright (C) 2022, Google LLC.
+ */
+
+#ifndef SELFTEST_KVM_TEST_HARNESS_H
+#define SELFTEST_KVM_TEST_HARNESS_H
+
+#include "kselftest_harness.h"
+
+#define KVM_ONE_VCPU_TEST_SUITE(name)					\
+	FIXTURE(name) {							\
+		struct kvm_vcpu *vcpu;					\
+	};								\
+									\
+	FIXTURE_SETUP(name) {						\
+		(void)vm_create_with_one_vcpu(&self->vcpu, NULL);	\
+	}								\
+									\
+	FIXTURE_TEARDOWN(name) {					\
+		kvm_vm_free(self->vcpu->vm);				\
+	}
+
+#define KVM_ONE_VCPU_TEST(suite, test, guestcode)			\
+static void __suite##_##test(struct kvm_vcpu *vcpu);			\
+									\
+TEST_F(suite, test)							\
+{									\
+	vcpu_arch_set_entry_point(self->vcpu, guestcode);		\
+	__suite##_##test(self->vcpu);					\
+}									\
+static void __suite##_##test(struct kvm_vcpu *vcpu)
+
+#endif /* SELFTEST_KVM_TEST_HARNESS_H */