[RFC PATCH v2 2/9] KVM: arm64: nv: selftests: Add simple test to run guest code in vEL2

[Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>]

Add simple test to run guest code with NV enabled. With NV enabled,
guest code runs in vEL2 context.

Signed-off-by: Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>
---
 .../selftests/kvm/arm64/nv_guest_hypervisor.c | 68 +++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c

diff --git a/tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c b/tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c
new file mode 100644
index 000000000000..7d7b3944e229
--- /dev/null
+++ b/tools/testing/selftests/kvm/arm64/nv_guest_hypervisor.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2025 Ampere Computing LLC
+ */
+#include <kvm_util.h>
+#include <nv_util.h>
+#include <processor.h>
+
+static void guest_code(void)
+{
+	if (read_sysreg(CurrentEL) == CurrentEL_EL2)
+		GUEST_PRINTF("Test PASS\n");
+	else
+		GUEST_FAIL("Fail to run in vEL2\n");
+
+	GUEST_DONE();
+}
+
+static void guest_undef_handler(struct ex_regs *regs)
+{
+	GUEST_FAIL("Unexpected exception far_el1 = 0x%lx", read_sysreg(far_el1));
+}
+
+static void test_run_vcpu(struct kvm_vcpu *vcpu)
+{
+	struct ucall uc;
+
+	do {
+		vcpu_run(vcpu);
+
+		switch (get_ucall(vcpu, &uc)) {
+		case UCALL_ABORT:
+			REPORT_GUEST_ASSERT(uc);
+			break;
+		case UCALL_PRINTF:
+			printf("%s", uc.buffer);
+			break;
+		case UCALL_DONE:
+			break;
+		default:
+			TEST_FAIL("Unknown ucall %lu", uc.cmd);
+		}
+	} while (uc.cmd != UCALL_DONE);
+}
+
+static void test_nv_guest_hypervisor(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	int gic_fd = -1;
+
+	vm = nv_vm_create_with_vcpus_gic(1, &vcpu, &gic_fd, guest_code);
+	vm_init_descriptor_tables(vm);
+	vcpu_init_descriptor_tables(vcpu);
+	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
+				ESR_ELx_EC_UNKNOWN, guest_undef_handler);
+
+	test_run_vcpu(vcpu);
+
+	vgic_v3_close(gic_fd);
+	kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+	test_nv_guest_hypervisor();
+	return 0;
+}
-- 
2.48.1