KVM: s390: selftests: Verify reject memory region operations for ucontrol VMs

Add a test case verifying KVM_SET_USER_MEMORY_REGION and
KVM_SET_USER_MEMORY_REGION2 cannot be executed on ucontrol VMs.

Executing this test case on not patched kernels will cause a null
pointer dereference in the host kernel.
This is fixed with commit:
commit 7816e58 ("kvm: s390: Reject memory region operations for ucontrol VMs")

Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20241107141024.238916-4-schlameuss@linux.ibm.com
[frankja@linux.ibm.com: Fixed patch prefix]
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-ID: <20241107141024.238916-4-schlameuss@linux.ibm.com>

Author: schlac

tools/testing/selftests/kvm/s390x/ucontrol_test.c

@@ -440,6 +440,28 @@ static void uc_assert_diag44(FIXTURE_DATA(uc_kvm) * self)
 	TEST_ASSERT_EQ(0x440000, sie_block->ipb);
 }
 
+TEST_F(uc_kvm, uc_no_user_region)
+{
+	struct kvm_userspace_memory_region region = {
+		.slot = 1,
+		.guest_phys_addr = self->code_gpa,
+		.memory_size = VM_MEM_EXT_SIZE,
+		.userspace_addr = (uintptr_t)self->code_hva,
+	};
+	struct kvm_userspace_memory_region2 region2 = {
+		.slot = 1,
+		.guest_phys_addr = self->code_gpa,
+		.memory_size = VM_MEM_EXT_SIZE,
+		.userspace_addr = (uintptr_t)self->code_hva,
+	};
+
+	ASSERT_EQ(-1, ioctl(self->vm_fd, KVM_SET_USER_MEMORY_REGION, &region));
+	ASSERT_EQ(EINVAL, errno);
+
+	ASSERT_EQ(-1, ioctl(self->vm_fd, KVM_SET_USER_MEMORY_REGION2, &region2));
+	ASSERT_EQ(EINVAL, errno);
+}
+
 TEST_F(uc_kvm, uc_map_unmap)
 {
 	struct kvm_sync_regs *sync_regs = &self->run->s.regs;