1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2022, Google LLC.
4 */
5 #include <fcntl.h>
6 #include <limits.h>
7 #include <pthread.h>
8 #include <sched.h>
9 #include <signal.h>
10 #include <stdio.h>
11 #include <stdlib.h>
12 #include <string.h>
13 #include <sys/ioctl.h>
14
15 #include <linux/compiler.h>
16 #include <linux/kernel.h>
17 #include <linux/kvm_para.h>
18 #include <linux/memfd.h>
19 #include <linux/sizes.h>
20
21 #include <test_util.h>
22 #include <kvm_util.h>
23 #include <processor.h>
24
25 #define BASE_DATA_SLOT 10
26 #define BASE_DATA_GPA ((uint64_t)(1ull << 32))
27 #define PER_CPU_DATA_SIZE ((uint64_t)(SZ_2M + PAGE_SIZE))
28
29 /* Horrific macro so that the line info is captured accurately :-( */
30 #define memcmp_g(gpa, pattern, size) \
31 do { \
32 uint8_t *mem = (uint8_t *)gpa; \
33 size_t i; \
34 \
35 for (i = 0; i < size; i++) \
36 __GUEST_ASSERT(mem[i] == pattern, \
37 "Guest expected 0x%x at offset %lu (gpa 0x%lx), got 0x%x", \
38 pattern, i, gpa + i, mem[i]); \
39 } while (0)
40
memcmp_h(uint8_t * mem,uint64_t gpa,uint8_t pattern,size_t size)41 static void memcmp_h(uint8_t *mem, uint64_t gpa, uint8_t pattern, size_t size)
42 {
43 size_t i;
44
45 for (i = 0; i < size; i++)
46 TEST_ASSERT(mem[i] == pattern,
47 "Host expected 0x%x at gpa 0x%lx, got 0x%x",
48 pattern, gpa + i, mem[i]);
49 }
50
51 /*
52 * Run memory conversion tests with explicit conversion:
53 * Execute KVM hypercall to map/unmap gpa range which will cause userspace exit
54 * to back/unback private memory. Subsequent accesses by guest to the gpa range
55 * will not cause exit to userspace.
56 *
57 * Test memory conversion scenarios with following steps:
58 * 1) Access private memory using private access and verify that memory contents
59 * are not visible to userspace.
60 * 2) Convert memory to shared using explicit conversions and ensure that
61 * userspace is able to access the shared regions.
62 * 3) Convert memory back to private using explicit conversions and ensure that
63 * userspace is again not able to access converted private regions.
64 */
65
66 #define GUEST_STAGE(o, s) { .offset = o, .size = s }
67
68 enum ucall_syncs {
69 SYNC_SHARED,
70 SYNC_PRIVATE,
71 };
72
guest_sync_shared(uint64_t gpa,uint64_t size,uint8_t current_pattern,uint8_t new_pattern)73 static void guest_sync_shared(uint64_t gpa, uint64_t size,
74 uint8_t current_pattern, uint8_t new_pattern)
75 {
76 GUEST_SYNC5(SYNC_SHARED, gpa, size, current_pattern, new_pattern);
77 }
78
guest_sync_private(uint64_t gpa,uint64_t size,uint8_t pattern)79 static void guest_sync_private(uint64_t gpa, uint64_t size, uint8_t pattern)
80 {
81 GUEST_SYNC4(SYNC_PRIVATE, gpa, size, pattern);
82 }
83
84 /* Arbitrary values, KVM doesn't care about the attribute flags. */
85 #define MAP_GPA_SET_ATTRIBUTES BIT(0)
86 #define MAP_GPA_SHARED BIT(1)
87 #define MAP_GPA_DO_FALLOCATE BIT(2)
88
guest_map_mem(uint64_t gpa,uint64_t size,bool map_shared,bool do_fallocate)89 static void guest_map_mem(uint64_t gpa, uint64_t size, bool map_shared,
90 bool do_fallocate)
91 {
92 uint64_t flags = MAP_GPA_SET_ATTRIBUTES;
93
94 if (map_shared)
95 flags |= MAP_GPA_SHARED;
96 if (do_fallocate)
97 flags |= MAP_GPA_DO_FALLOCATE;
98 kvm_hypercall_map_gpa_range(gpa, size, flags);
99 }
100
guest_map_shared(uint64_t gpa,uint64_t size,bool do_fallocate)101 static void guest_map_shared(uint64_t gpa, uint64_t size, bool do_fallocate)
102 {
103 guest_map_mem(gpa, size, true, do_fallocate);
104 }
105
guest_map_private(uint64_t gpa,uint64_t size,bool do_fallocate)106 static void guest_map_private(uint64_t gpa, uint64_t size, bool do_fallocate)
107 {
108 guest_map_mem(gpa, size, false, do_fallocate);
109 }
110
111 struct {
112 uint64_t offset;
113 uint64_t size;
114 } static const test_ranges[] = {
115 GUEST_STAGE(0, PAGE_SIZE),
116 GUEST_STAGE(0, SZ_2M),
117 GUEST_STAGE(PAGE_SIZE, PAGE_SIZE),
118 GUEST_STAGE(PAGE_SIZE, SZ_2M),
119 GUEST_STAGE(SZ_2M, PAGE_SIZE),
120 };
121
guest_test_explicit_conversion(uint64_t base_gpa,bool do_fallocate)122 static void guest_test_explicit_conversion(uint64_t base_gpa, bool do_fallocate)
123 {
124 const uint8_t def_p = 0xaa;
125 const uint8_t init_p = 0xcc;
126 uint64_t j;
127 int i;
128
129 /* Memory should be shared by default. */
130 memset((void *)base_gpa, def_p, PER_CPU_DATA_SIZE);
131 memcmp_g(base_gpa, def_p, PER_CPU_DATA_SIZE);
132 guest_sync_shared(base_gpa, PER_CPU_DATA_SIZE, def_p, init_p);
133
134 memcmp_g(base_gpa, init_p, PER_CPU_DATA_SIZE);
135
136 for (i = 0; i < ARRAY_SIZE(test_ranges); i++) {
137 uint64_t gpa = base_gpa + test_ranges[i].offset;
138 uint64_t size = test_ranges[i].size;
139 uint8_t p1 = 0x11;
140 uint8_t p2 = 0x22;
141 uint8_t p3 = 0x33;
142 uint8_t p4 = 0x44;
143
144 /*
145 * Set the test region to pattern one to differentiate it from
146 * the data range as a whole (contains the initial pattern).
147 */
148 memset((void *)gpa, p1, size);
149
150 /*
151 * Convert to private, set and verify the private data, and
152 * then verify that the rest of the data (map shared) still
153 * holds the initial pattern, and that the host always sees the
154 * shared memory (initial pattern). Unlike shared memory,
155 * punching a hole in private memory is destructive, i.e.
156 * previous values aren't guaranteed to be preserved.
157 */
158 guest_map_private(gpa, size, do_fallocate);
159
160 if (size > PAGE_SIZE) {
161 memset((void *)gpa, p2, PAGE_SIZE);
162 goto skip;
163 }
164
165 memset((void *)gpa, p2, size);
166 guest_sync_private(gpa, size, p1);
167
168 /*
169 * Verify that the private memory was set to pattern two, and
170 * that shared memory still holds the initial pattern.
171 */
172 memcmp_g(gpa, p2, size);
173 if (gpa > base_gpa)
174 memcmp_g(base_gpa, init_p, gpa - base_gpa);
175 if (gpa + size < base_gpa + PER_CPU_DATA_SIZE)
176 memcmp_g(gpa + size, init_p,
177 (base_gpa + PER_CPU_DATA_SIZE) - (gpa + size));
178
179 /*
180 * Convert odd-number page frames back to shared to verify KVM
181 * also correctly handles holes in private ranges.
182 */
183 for (j = 0; j < size; j += PAGE_SIZE) {
184 if ((j >> PAGE_SHIFT) & 1) {
185 guest_map_shared(gpa + j, PAGE_SIZE, do_fallocate);
186 guest_sync_shared(gpa + j, PAGE_SIZE, p1, p3);
187
188 memcmp_g(gpa + j, p3, PAGE_SIZE);
189 } else {
190 guest_sync_private(gpa + j, PAGE_SIZE, p1);
191 }
192 }
193
194 skip:
195 /*
196 * Convert the entire region back to shared, explicitly write
197 * pattern three to fill in the even-number frames before
198 * asking the host to verify (and write pattern four).
199 */
200 guest_map_shared(gpa, size, do_fallocate);
201 memset((void *)gpa, p3, size);
202 guest_sync_shared(gpa, size, p3, p4);
203 memcmp_g(gpa, p4, size);
204
205 /* Reset the shared memory back to the initial pattern. */
206 memset((void *)gpa, init_p, size);
207
208 /*
209 * Free (via PUNCH_HOLE) *all* private memory so that the next
210 * iteration starts from a clean slate, e.g. with respect to
211 * whether or not there are pages/folios in guest_mem.
212 */
213 guest_map_shared(base_gpa, PER_CPU_DATA_SIZE, true);
214 }
215 }
216
guest_punch_hole(uint64_t gpa,uint64_t size)217 static void guest_punch_hole(uint64_t gpa, uint64_t size)
218 {
219 /* "Mapping" memory shared via fallocate() is done via PUNCH_HOLE. */
220 uint64_t flags = MAP_GPA_SHARED | MAP_GPA_DO_FALLOCATE;
221
222 kvm_hypercall_map_gpa_range(gpa, size, flags);
223 }
224
225 /*
226 * Test that PUNCH_HOLE actually frees memory by punching holes without doing a
227 * proper conversion. Freeing (PUNCH_HOLE) should zap SPTEs, and reallocating
228 * (subsequent fault) should zero memory.
229 */
guest_test_punch_hole(uint64_t base_gpa,bool precise)230 static void guest_test_punch_hole(uint64_t base_gpa, bool precise)
231 {
232 const uint8_t init_p = 0xcc;
233 int i;
234
235 /*
236 * Convert the entire range to private, this testcase is all about
237 * punching holes in guest_memfd, i.e. shared mappings aren't needed.
238 */
239 guest_map_private(base_gpa, PER_CPU_DATA_SIZE, false);
240
241 for (i = 0; i < ARRAY_SIZE(test_ranges); i++) {
242 uint64_t gpa = base_gpa + test_ranges[i].offset;
243 uint64_t size = test_ranges[i].size;
244
245 /*
246 * Free all memory before each iteration, even for the !precise
247 * case where the memory will be faulted back in. Freeing and
248 * reallocating should obviously work, and freeing all memory
249 * minimizes the probability of cross-testcase influence.
250 */
251 guest_punch_hole(base_gpa, PER_CPU_DATA_SIZE);
252
253 /* Fault-in and initialize memory, and verify the pattern. */
254 if (precise) {
255 memset((void *)gpa, init_p, size);
256 memcmp_g(gpa, init_p, size);
257 } else {
258 memset((void *)base_gpa, init_p, PER_CPU_DATA_SIZE);
259 memcmp_g(base_gpa, init_p, PER_CPU_DATA_SIZE);
260 }
261
262 /*
263 * Punch a hole at the target range and verify that reads from
264 * the guest succeed and return zeroes.
265 */
266 guest_punch_hole(gpa, size);
267 memcmp_g(gpa, 0, size);
268 }
269 }
270
guest_code(uint64_t base_gpa)271 static void guest_code(uint64_t base_gpa)
272 {
273 /*
274 * Run the conversion test twice, with and without doing fallocate() on
275 * the guest_memfd backing when converting between shared and private.
276 */
277 guest_test_explicit_conversion(base_gpa, false);
278 guest_test_explicit_conversion(base_gpa, true);
279
280 /*
281 * Run the PUNCH_HOLE test twice too, once with the entire guest_memfd
282 * faulted in, once with only the target range faulted in.
283 */
284 guest_test_punch_hole(base_gpa, false);
285 guest_test_punch_hole(base_gpa, true);
286 GUEST_DONE();
287 }
288
handle_exit_hypercall(struct kvm_vcpu * vcpu)289 static void handle_exit_hypercall(struct kvm_vcpu *vcpu)
290 {
291 struct kvm_run *run = vcpu->run;
292 uint64_t gpa = run->hypercall.args[0];
293 uint64_t size = run->hypercall.args[1] * PAGE_SIZE;
294 bool set_attributes = run->hypercall.args[2] & MAP_GPA_SET_ATTRIBUTES;
295 bool map_shared = run->hypercall.args[2] & MAP_GPA_SHARED;
296 bool do_fallocate = run->hypercall.args[2] & MAP_GPA_DO_FALLOCATE;
297 struct kvm_vm *vm = vcpu->vm;
298
299 TEST_ASSERT(run->hypercall.nr == KVM_HC_MAP_GPA_RANGE,
300 "Wanted MAP_GPA_RANGE (%u), got '%llu'",
301 KVM_HC_MAP_GPA_RANGE, run->hypercall.nr);
302
303 if (do_fallocate)
304 vm_guest_mem_fallocate(vm, gpa, size, map_shared);
305
306 if (set_attributes)
307 vm_set_memory_attributes(vm, gpa, size,
308 map_shared ? 0 : KVM_MEMORY_ATTRIBUTE_PRIVATE);
309 run->hypercall.ret = 0;
310 }
311
312 static bool run_vcpus;
313
__test_mem_conversions(void * __vcpu)314 static void *__test_mem_conversions(void *__vcpu)
315 {
316 struct kvm_vcpu *vcpu = __vcpu;
317 struct kvm_run *run = vcpu->run;
318 struct kvm_vm *vm = vcpu->vm;
319 struct ucall uc;
320
321 while (!READ_ONCE(run_vcpus))
322 ;
323
324 for ( ;; ) {
325 vcpu_run(vcpu);
326
327 if (run->exit_reason == KVM_EXIT_HYPERCALL) {
328 handle_exit_hypercall(vcpu);
329 continue;
330 }
331
332 TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
333 "Wanted KVM_EXIT_IO, got exit reason: %u (%s)",
334 run->exit_reason, exit_reason_str(run->exit_reason));
335
336 switch (get_ucall(vcpu, &uc)) {
337 case UCALL_ABORT:
338 REPORT_GUEST_ASSERT(uc);
339 case UCALL_SYNC: {
340 uint64_t gpa = uc.args[1];
341 size_t size = uc.args[2];
342 size_t i;
343
344 TEST_ASSERT(uc.args[0] == SYNC_SHARED ||
345 uc.args[0] == SYNC_PRIVATE,
346 "Unknown sync command '%ld'", uc.args[0]);
347
348 for (i = 0; i < size; i += vm->page_size) {
349 size_t nr_bytes = min_t(size_t, vm->page_size, size - i);
350 uint8_t *hva = addr_gpa2hva(vm, gpa + i);
351
352 /* In all cases, the host should observe the shared data. */
353 memcmp_h(hva, gpa + i, uc.args[3], nr_bytes);
354
355 /* For shared, write the new pattern to guest memory. */
356 if (uc.args[0] == SYNC_SHARED)
357 memset(hva, uc.args[4], nr_bytes);
358 }
359 break;
360 }
361 case UCALL_DONE:
362 return NULL;
363 default:
364 TEST_FAIL("Unknown ucall 0x%lx.", uc.cmd);
365 }
366 }
367 }
368
test_mem_conversions(enum vm_mem_backing_src_type src_type,uint32_t nr_vcpus,uint32_t nr_memslots)369 static void test_mem_conversions(enum vm_mem_backing_src_type src_type, uint32_t nr_vcpus,
370 uint32_t nr_memslots)
371 {
372 /*
373 * Allocate enough memory so that each vCPU's chunk of memory can be
374 * naturally aligned with respect to the size of the backing store.
375 */
376 const size_t alignment = max_t(size_t, SZ_2M, get_backing_src_pagesz(src_type));
377 const size_t per_cpu_size = align_up(PER_CPU_DATA_SIZE, alignment);
378 const size_t memfd_size = per_cpu_size * nr_vcpus;
379 const size_t slot_size = memfd_size / nr_memslots;
380 struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
381 pthread_t threads[KVM_MAX_VCPUS];
382 struct kvm_vm *vm;
383 int memfd, i, r;
384
385 const struct vm_shape shape = {
386 .mode = VM_MODE_DEFAULT,
387 .type = KVM_X86_SW_PROTECTED_VM,
388 };
389
390 TEST_ASSERT(slot_size * nr_memslots == memfd_size,
391 "The memfd size (0x%lx) needs to be cleanly divisible by the number of memslots (%u)",
392 memfd_size, nr_memslots);
393 vm = __vm_create_with_vcpus(shape, nr_vcpus, 0, guest_code, vcpus);
394
395 vm_enable_cap(vm, KVM_CAP_EXIT_HYPERCALL, (1 << KVM_HC_MAP_GPA_RANGE));
396
397 memfd = vm_create_guest_memfd(vm, memfd_size, 0);
398
399 for (i = 0; i < nr_memslots; i++)
400 vm_mem_add(vm, src_type, BASE_DATA_GPA + slot_size * i,
401 BASE_DATA_SLOT + i, slot_size / vm->page_size,
402 KVM_MEM_GUEST_MEMFD, memfd, slot_size * i);
403
404 for (i = 0; i < nr_vcpus; i++) {
405 uint64_t gpa = BASE_DATA_GPA + i * per_cpu_size;
406
407 vcpu_args_set(vcpus[i], 1, gpa);
408
409 /*
410 * Map only what is needed so that an out-of-bounds access
411 * results #PF => SHUTDOWN instead of data corruption.
412 */
413 virt_map(vm, gpa, gpa, PER_CPU_DATA_SIZE / vm->page_size);
414
415 pthread_create(&threads[i], NULL, __test_mem_conversions, vcpus[i]);
416 }
417
418 WRITE_ONCE(run_vcpus, true);
419
420 for (i = 0; i < nr_vcpus; i++)
421 pthread_join(threads[i], NULL);
422
423 kvm_vm_free(vm);
424
425 /*
426 * Allocate and free memory from the guest_memfd after closing the VM
427 * fd. The guest_memfd is gifted a reference to its owning VM, i.e.
428 * should prevent the VM from being fully destroyed until the last
429 * reference to the guest_memfd is also put.
430 */
431 r = fallocate(memfd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0, memfd_size);
432 TEST_ASSERT(!r, __KVM_SYSCALL_ERROR("fallocate()", r));
433
434 r = fallocate(memfd, FALLOC_FL_KEEP_SIZE, 0, memfd_size);
435 TEST_ASSERT(!r, __KVM_SYSCALL_ERROR("fallocate()", r));
436
437 close(memfd);
438 }
439
usage(const char * cmd)440 static void usage(const char *cmd)
441 {
442 puts("");
443 printf("usage: %s [-h] [-m nr_memslots] [-s mem_type] [-n nr_vcpus]\n", cmd);
444 puts("");
445 backing_src_help("-s");
446 puts("");
447 puts(" -n: specify the number of vcpus (default: 1)");
448 puts("");
449 puts(" -m: specify the number of memslots (default: 1)");
450 puts("");
451 }
452
main(int argc,char * argv[])453 int main(int argc, char *argv[])
454 {
455 enum vm_mem_backing_src_type src_type = DEFAULT_VM_MEM_SRC;
456 uint32_t nr_memslots = 1;
457 uint32_t nr_vcpus = 1;
458 int opt;
459
460 TEST_REQUIRE(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM));
461
462 while ((opt = getopt(argc, argv, "hm:s:n:")) != -1) {
463 switch (opt) {
464 case 's':
465 src_type = parse_backing_src_type(optarg);
466 break;
467 case 'n':
468 nr_vcpus = atoi_positive("nr_vcpus", optarg);
469 break;
470 case 'm':
471 nr_memslots = atoi_positive("nr_memslots", optarg);
472 break;
473 case 'h':
474 default:
475 usage(argv[0]);
476 exit(0);
477 }
478 }
479
480 test_mem_conversions(src_type, nr_vcpus, nr_memslots);
481
482 return 0;
483 }
484