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From:   Peter Xu <peterx@redhat.com>
To:     linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc:     Andrea Arcangeli <aarcange@redhat.com>, peterx@redhat.com,
        David Hildenbrand <david@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nadav Amit <nadav.amit@gmail.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Leonardo Bras Soares Passos <lsoaresp@redhat.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>
Subject: [PATCH 16/29] selftests/mm: UFFDIO_API test
Date:   Thu, 30 Mar 2023 12:07:52 -0400
Message-Id: <20230330160752.3107283-1-peterx@redhat.com>
In-Reply-To: <20230330155707.3106228-1-peterx@redhat.com>
References: <20230330155707.3106228-1-peterx@redhat.com>
MIME-Version: 1.0
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Precedence: bulk

Add one simple test for UFFDIO_API.  With that, I also added a bunch of
small but handy helpers along the way.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 tools/testing/selftests/mm/uffd-unit-tests.c | 111 ++++++++++++++++++-
 tools/testing/selftests/mm/vm_util.c         |  10 ++
 2 files changed, 120 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
index 6857388783be..dfb44ffad5f5 100644
--- a/tools/testing/selftests/mm/uffd-unit-tests.c
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -9,9 +9,118 @@
 
 #ifdef __NR_userfaultfd
 
+struct {
+	unsigned int pass, skip, fail, total;
+} uffd_test_acct;
+
+static void uffd_test_report(void)
+{
+	printf("Userfaults unit tests: pass=%u, skip=%u, fail=%u (total=%u)\n",
+	       uffd_test_acct.pass,
+	       uffd_test_acct.skip,
+	       uffd_test_acct.fail,
+	       uffd_test_acct.total);
+}
+
+static void uffd_test_pass(void)
+{
+	printf("done\n");
+	uffd_test_acct.pass++;
+}
+
+#define  uffd_test_start(...)  do {		\
+		printf(__VA_ARGS__);		\
+		printf("... ");			\
+		uffd_test_acct.total++;		\
+	} while (0)
+
+#define  uffd_test_fail(...)  do {		\
+		printf("failed [reason: ");	\
+		printf(__VA_ARGS__);		\
+		printf("]\n");			\
+		uffd_test_acct.fail++;		\
+	} while (0)
+
+#define  uffd_test_skip(...)  do {		\
+		printf("skipped [reason: ");	\
+		printf(__VA_ARGS__);		\
+		printf("]\n");			\
+		uffd_test_acct.skip++;		\
+	} while (0)
+
+/*
+ * Returns 1 if specific userfaultfd supported, 0 otherwise.  Note, we'll
+ * return 1 even if some test failed as long as uffd supported, because in
+ * that case we still want to proceed with the rest uffd unit tests.
+ */
+static int test_uffd_api(bool use_dev)
+{
+	struct uffdio_api uffdio_api;
+	int uffd;
+
+	uffd_test_start("UFFDIO_API (with %s)",
+			use_dev ? "/dev/userfaultfd" : "syscall");
+
+	if (use_dev)
+		uffd = uffd_open_dev(UFFD_FLAGS);
+	else
+		uffd = uffd_open_sys(UFFD_FLAGS);
+	if (uffd < 0) {
+		uffd_test_skip("cannot open userfaultfd handle");
+		return 0;
+	}
+
+	/* Test wrong UFFD_API */
+	uffdio_api.api = 0xab;
+	uffdio_api.features = 0;
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
+		uffd_test_fail("UFFDIO_API should fail with wrong api but didn't");
+		goto out;
+	}
+
+	/* Test wrong feature bit */
+	uffdio_api.api = UFFD_API;
+	uffdio_api.features = BIT_ULL(63);
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
+		uffd_test_fail("UFFDIO_API should fail with wrong feature but didn't");
+		goto out;
+	}
+
+	/* Test normal UFFDIO_API */
+	uffdio_api.api = UFFD_API;
+	uffdio_api.features = 0;
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api)) {
+		uffd_test_fail("UFFDIO_API should succeed but failed");
+		goto out;
+	}
+
+	/* Test double requests of UFFDIO_API with a random feature set */
+	uffdio_api.features = BIT_ULL(0);
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
+		uffd_test_fail("UFFDIO_API should reject initialized uffd");
+		goto out;
+	}
+
+	uffd_test_pass();
+out:
+	close(uffd);
+	/* We have a valid uffd handle */
+	return 1;
+}
+
 int main(int argc, char *argv[])
 {
-	return KSFT_PASS;
+	int has_uffd;
+
+	has_uffd = test_uffd_api(false);
+	has_uffd |= test_uffd_api(true);
+
+	if (!has_uffd) {
+		printf("Userfaultfd not supported or unprivileged, skip all tests\n");
+		exit(KSFT_SKIP);
+	}
+	uffd_test_report();
+	return uffd_test_acct.fail ? KSFT_FAIL : KSFT_PASS;
 }
 
 #else /* __NR_userfaultfd */
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 7c2bf88d6393..62fcf039d6b7 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -254,3 +254,13 @@ int uffd_open_sys(unsigned int flags)
 	return -1;
 #endif
 }
+
+int uffd_open(unsigned int flags)
+{
+	int uffd = uffd_open_sys(flags);
+
+	if (uffd < 0)
+		uffd = uffd_open_dev(flags);
+
+	return uffd;
+}
-- 
2.39.1