KVM: selftests: Add negative test cases for punch hole for guest_memfd()

Add test cases to check for punch hole of guest_memfd to reject unaligned
offset or size.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Link: https://lore.kernel.org/r/bf9094185cc93cc1ff0efac0349258cf68046c99.1695327124.git.isaku.yamahata@intel.com
[sean: tweak function name, print offset+len on failure]
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: yamahata

tools/testing/selftests/kvm/guest_memfd_test.c

@@ -91,6 +91,36 @@ static void test_fallocate(int fd, size_t page_size, size_t total_size)
 	TEST_ASSERT(!ret, "fallocate to restore punched hole should succeed");
 }
 
+static void test_invalid_punch_hole(int fd, size_t page_size, size_t total_size)
+{
+	struct {
+		off_t offset;
+		off_t len;
+	} testcases[] = {
+		{0, 1},
+		{0, page_size - 1},
+		{0, page_size + 1},
+
+		{1, 1},
+		{1, page_size - 1},
+		{1, page_size},
+		{1, page_size + 1},
+
+		{page_size, 1},
+		{page_size, page_size - 1},
+		{page_size, page_size + 1},
+	};
+	int ret, i;
+
+	for (i = 0; i < ARRAY_SIZE(testcases); i++) {
+		ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
+				testcases[i].offset, testcases[i].len);
+		TEST_ASSERT(ret == -1 && errno == EINVAL,
+			    "PUNCH_HOLE with !PAGE_SIZE offset (%lx) and/or length (%lx) should fail",
+			    testcases[i].offset, testcases[i].len);
+	}
+}
+
 static void test_create_guest_memfd_invalid(struct kvm_vm *vm)
 {
 	uint64_t valid_flags = 0;
@@ -160,6 +190,7 @@ int main(int argc, char *argv[])
 	test_mmap(fd, page_size);
 	test_file_size(fd, page_size, total_size);
 	test_fallocate(fd, page_size, total_size);
+	test_invalid_punch_hole(fd, page_size, total_size);
 
 	close(fd);
 }