xref: /linux/tools/testing/selftests/kvm/guest_memfd_test.c (revision eed4edda910fe34dfae8c6bfbcf57f4593a54295)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright Intel Corporation, 2023
4  *
5  * Author: Chao Peng <chao.p.peng@linux.intel.com>
6  */
7 
8 #define _GNU_SOURCE
9 #include <stdlib.h>
10 #include <string.h>
11 #include <unistd.h>
12 #include <errno.h>
13 #include <stdio.h>
14 #include <fcntl.h>
15 
16 #include <linux/bitmap.h>
17 #include <linux/falloc.h>
18 #include <sys/mman.h>
19 #include <sys/types.h>
20 #include <sys/stat.h>
21 
22 #include "test_util.h"
23 #include "kvm_util_base.h"
24 
25 static void test_file_read_write(int fd)
26 {
27 	char buf[64];
28 
29 	TEST_ASSERT(read(fd, buf, sizeof(buf)) < 0,
30 		    "read on a guest_mem fd should fail");
31 	TEST_ASSERT(write(fd, buf, sizeof(buf)) < 0,
32 		    "write on a guest_mem fd should fail");
33 	TEST_ASSERT(pread(fd, buf, sizeof(buf), 0) < 0,
34 		    "pread on a guest_mem fd should fail");
35 	TEST_ASSERT(pwrite(fd, buf, sizeof(buf), 0) < 0,
36 		    "pwrite on a guest_mem fd should fail");
37 }
38 
39 static void test_mmap(int fd, size_t page_size)
40 {
41 	char *mem;
42 
43 	mem = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
44 	TEST_ASSERT_EQ(mem, MAP_FAILED);
45 }
46 
47 static void test_file_size(int fd, size_t page_size, size_t total_size)
48 {
49 	struct stat sb;
50 	int ret;
51 
52 	ret = fstat(fd, &sb);
53 	TEST_ASSERT(!ret, "fstat should succeed");
54 	TEST_ASSERT_EQ(sb.st_size, total_size);
55 	TEST_ASSERT_EQ(sb.st_blksize, page_size);
56 }
57 
58 static void test_fallocate(int fd, size_t page_size, size_t total_size)
59 {
60 	int ret;
61 
62 	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, total_size);
63 	TEST_ASSERT(!ret, "fallocate with aligned offset and size should succeed");
64 
65 	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
66 			page_size - 1, page_size);
67 	TEST_ASSERT(ret, "fallocate with unaligned offset should fail");
68 
69 	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, total_size, page_size);
70 	TEST_ASSERT(ret, "fallocate beginning at total_size should fail");
71 
72 	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, total_size + page_size, page_size);
73 	TEST_ASSERT(ret, "fallocate beginning after total_size should fail");
74 
75 	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
76 			total_size, page_size);
77 	TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) at total_size should succeed");
78 
79 	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
80 			total_size + page_size, page_size);
81 	TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) after total_size should succeed");
82 
83 	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
84 			page_size, page_size - 1);
85 	TEST_ASSERT(ret, "fallocate with unaligned size should fail");
86 
87 	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
88 			page_size, page_size);
89 	TEST_ASSERT(!ret, "fallocate(PUNCH_HOLE) with aligned offset and size should succeed");
90 
91 	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE, page_size, page_size);
92 	TEST_ASSERT(!ret, "fallocate to restore punched hole should succeed");
93 }
94 
95 static void test_invalid_punch_hole(int fd, size_t page_size, size_t total_size)
96 {
97 	struct {
98 		off_t offset;
99 		off_t len;
100 	} testcases[] = {
101 		{0, 1},
102 		{0, page_size - 1},
103 		{0, page_size + 1},
104 
105 		{1, 1},
106 		{1, page_size - 1},
107 		{1, page_size},
108 		{1, page_size + 1},
109 
110 		{page_size, 1},
111 		{page_size, page_size - 1},
112 		{page_size, page_size + 1},
113 	};
114 	int ret, i;
115 
116 	for (i = 0; i < ARRAY_SIZE(testcases); i++) {
117 		ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
118 				testcases[i].offset, testcases[i].len);
119 		TEST_ASSERT(ret == -1 && errno == EINVAL,
120 			    "PUNCH_HOLE with !PAGE_SIZE offset (%lx) and/or length (%lx) should fail",
121 			    testcases[i].offset, testcases[i].len);
122 	}
123 }
124 
125 static void test_create_guest_memfd_invalid(struct kvm_vm *vm)
126 {
127 	size_t page_size = getpagesize();
128 	uint64_t flag;
129 	size_t size;
130 	int fd;
131 
132 	for (size = 1; size < page_size; size++) {
133 		fd = __vm_create_guest_memfd(vm, size, 0);
134 		TEST_ASSERT(fd == -1 && errno == EINVAL,
135 			    "guest_memfd() with non-page-aligned page size '0x%lx' should fail with EINVAL",
136 			    size);
137 	}
138 
139 	for (flag = 0; flag; flag <<= 1) {
140 		fd = __vm_create_guest_memfd(vm, page_size, flag);
141 		TEST_ASSERT(fd == -1 && errno == EINVAL,
142 			    "guest_memfd() with flag '0x%lx' should fail with EINVAL",
143 			    flag);
144 	}
145 }
146 
147 static void test_create_guest_memfd_multiple(struct kvm_vm *vm)
148 {
149 	int fd1, fd2, ret;
150 	struct stat st1, st2;
151 
152 	fd1 = __vm_create_guest_memfd(vm, 4096, 0);
153 	TEST_ASSERT(fd1 != -1, "memfd creation should succeed");
154 
155 	ret = fstat(fd1, &st1);
156 	TEST_ASSERT(ret != -1, "memfd fstat should succeed");
157 	TEST_ASSERT(st1.st_size == 4096, "memfd st_size should match requested size");
158 
159 	fd2 = __vm_create_guest_memfd(vm, 8192, 0);
160 	TEST_ASSERT(fd2 != -1, "memfd creation should succeed");
161 
162 	ret = fstat(fd2, &st2);
163 	TEST_ASSERT(ret != -1, "memfd fstat should succeed");
164 	TEST_ASSERT(st2.st_size == 8192, "second memfd st_size should match requested size");
165 
166 	ret = fstat(fd1, &st1);
167 	TEST_ASSERT(ret != -1, "memfd fstat should succeed");
168 	TEST_ASSERT(st1.st_size == 4096, "first memfd st_size should still match requested size");
169 	TEST_ASSERT(st1.st_ino != st2.st_ino, "different memfd should have different inode numbers");
170 }
171 
172 int main(int argc, char *argv[])
173 {
174 	size_t page_size;
175 	size_t total_size;
176 	int fd;
177 	struct kvm_vm *vm;
178 
179 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_GUEST_MEMFD));
180 
181 	page_size = getpagesize();
182 	total_size = page_size * 4;
183 
184 	vm = vm_create_barebones();
185 
186 	test_create_guest_memfd_invalid(vm);
187 	test_create_guest_memfd_multiple(vm);
188 
189 	fd = vm_create_guest_memfd(vm, total_size, 0);
190 
191 	test_file_read_write(fd);
192 	test_mmap(fd, page_size);
193 	test_file_size(fd, page_size, total_size);
194 	test_fallocate(fd, page_size, total_size);
195 	test_invalid_punch_hole(fd, page_size, total_size);
196 
197 	close(fd);
198 }
199