KVM: selftests: simplify setup_demand_paging error handling

A small cleanup. Our caller writes:

  r = setup_demand_paging(...);
  if (r < 0) exit(-r);

Since we're just going to exit anyway, instead of returning an error we
can just re-use TEST_ASSERT. This makes the caller simpler, as well as
the function itself - no need to write our branches, etc.
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Message-Id: <20210519200339.829146-3-axelrasmussen@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/demand_paging_test.c

@@ -9,6 +9,7 @@
 
 #define _GNU_SOURCE /* for pipe2 */
 
+#include <inttypes.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
@@ -198,42 +199,32 @@ static void *uffd_handler_thread_fn(void *arg)
 	return NULL;
 }
 
-static int setup_demand_paging(struct kvm_vm *vm,
-			       pthread_t *uffd_handler_thread, int pipefd,
-			       useconds_t uffd_delay,
-			       struct uffd_handler_args *uffd_args,
-			       void *hva, uint64_t len)
+static void setup_demand_paging(struct kvm_vm *vm,
+				pthread_t *uffd_handler_thread, int pipefd,
+				useconds_t uffd_delay,
+				struct uffd_handler_args *uffd_args,
+				void *hva, uint64_t len)
 {
 	int uffd;
 	struct uffdio_api uffdio_api;
 	struct uffdio_register uffdio_register;
 
 	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
-	if (uffd == -1) {
-		pr_info("uffd creation failed\n");
-		return -1;
-	}
+	TEST_ASSERT(uffd >= 0, "uffd creation failed, errno: %d", errno);
 
 	uffdio_api.api = UFFD_API;
 	uffdio_api.features = 0;
-	if (ioctl(uffd, UFFDIO_API, &uffdio_api) == -1) {
-		pr_info("ioctl uffdio_api failed\n");
-		return -1;
-	}
+	TEST_ASSERT(ioctl(uffd, UFFDIO_API, &uffdio_api) != -1,
+		    "ioctl UFFDIO_API failed: %" PRIu64,
+		    (uint64_t)uffdio_api.api);
 
 	uffdio_register.range.start = (uint64_t)hva;
 	uffdio_register.range.len = len;
 	uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
-	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) == -1) {
-		pr_info("ioctl uffdio_register failed\n");
-		return -1;
-	}
-
-	if ((uffdio_register.ioctls & UFFD_API_RANGE_IOCTLS) !=
-			UFFD_API_RANGE_IOCTLS) {
-		pr_info("unexpected userfaultfd ioctl set\n");
-		return -1;
-	}
+	TEST_ASSERT(ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) != -1,
+		    "ioctl UFFDIO_REGISTER failed");
+	TEST_ASSERT((uffdio_register.ioctls & UFFD_API_RANGE_IOCTLS) ==
+		    UFFD_API_RANGE_IOCTLS, "unexpected userfaultfd ioctl set");
 
 	uffd_args->uffd = uffd;
 	uffd_args->pipefd = pipefd;
@@ -243,8 +234,6 @@ static int setup_demand_paging(struct kvm_vm *vm,
 
 	PER_VCPU_DEBUG("Created uffd thread for HVA range [%p, %p)\n",
 		       hva, hva + len);
-
-	return 0;
 }
 
 struct test_params {
@@ -321,13 +310,10 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 				  O_CLOEXEC | O_NONBLOCK);
 			TEST_ASSERT(!r, "Failed to set up pipefd");
 
-			r = setup_demand_paging(vm,
-						&uffd_handler_threads[vcpu_id],
-						pipefds[vcpu_id * 2],
-						p->uffd_delay, &uffd_args[vcpu_id],
-						vcpu_hva, vcpu_mem_size);
-			if (r < 0)
-				exit(-r);
+			setup_demand_paging(vm, &uffd_handler_threads[vcpu_id],
+					    pipefds[vcpu_id * 2], p->uffd_delay,
+					    &uffd_args[vcpu_id], vcpu_hva,
+					    vcpu_mem_size);
 		}
 	}