selftests/udmabuf: add tests to verify data after page migration

Since the memfd pages associated with a udmabuf may be migrated as part of
udmabuf create, we need to verify the data coherency after successful
migration. The new tests added in this patch try to do just that using 4k
sized pages and also 2 MB sized huge pages for the memfd.

Successful completion of the tests would mean that there is no disconnect
between the memfd pages and the ones associated with a udmabuf. And,
these tests can also be augmented in the future to test newer udmabuf
features (such as handling memfd hole punch).

The idea for these tests comes from a patch by Mike Kravetz here:
https://lists.freedesktop.org/archives/dri-devel/2023-June/410623.html

v1->v2: (suggestions from Shuah)
- Use ksft_* functions to print and capture results of tests
- Use appropriate KSFT_* status codes for exit()
- Add Mike Kravetz's suggested-by tag

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Vivek Kasireddy <[e-mail]>
Suggested-by: Mike Kravetz <[e-mail]>
Acked-by: Dave Airlie <[e-mail]>
Acked-by: Gerd Hoffmann <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Cc: David Hildenbrand <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Hugh Dickins <[e-mail]>
Cc: Peter Xu <[e-mail]>
Cc: Jason Gunthorpe <[e-mail]>
Cc: Dongwon Kim <[e-mail]>
Cc: Junxiao Chang <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Matthew Wilcox (Oracle) <[e-mail]>
Cc: Oscar Salvador <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

tools/testing/selftests/drivers/dma-buf/udmabuf.c

···
 #include <errno.h>
 #include <fcntl.h>
 #include <malloc.h>
+#include <stdbool.h>
 
 #include <sys/ioctl.h>
 #include <sys/syscall.h>
+#include <sys/mman.h>
 #include <linux/memfd.h>
 #include <linux/udmabuf.h>
+#include "../../kselftest.h"
 
 #define TEST_PREFIX	"drivers/dma-buf/udmabuf"
 #define NUM_PAGES       4
+#define NUM_ENTRIES     4
+#define MEMFD_SIZE      1024 /* in pages */
 
-static int memfd_create(const char *name, unsigned int flags)
+static unsigned int page_size;
+
+static int create_memfd_with_seals(off64_t size, bool hpage)
 {
-	return syscall(__NR_memfd_create, name, flags);
+	int memfd, ret;
+	unsigned int flags = MFD_ALLOW_SEALING;
+
+	if (hpage)
+		flags |= MFD_HUGETLB;
+
+	memfd = memfd_create("udmabuf-test", flags);
+	if (memfd < 0) {
+		ksft_print_msg("%s: [skip,no-memfd]\n", TEST_PREFIX);
+		exit(KSFT_SKIP);
+	}
+
+	ret = fcntl(memfd, F_ADD_SEALS, F_SEAL_SHRINK);
+	if (ret < 0) {
+		ksft_print_msg("%s: [skip,fcntl-add-seals]\n", TEST_PREFIX);
+		exit(KSFT_SKIP);
+	}
+
+	ret = ftruncate(memfd, size);
+	if (ret == -1) {
+		ksft_print_msg("%s: [FAIL,memfd-truncate]\n", TEST_PREFIX);
+		exit(KSFT_FAIL);
+	}
+
+	return memfd;
+}
+
+static int create_udmabuf_list(int devfd, int memfd, off64_t memfd_size)
+{
+	struct udmabuf_create_list *list;
+	int ubuf_fd, i;
+
+	list = malloc(sizeof(struct udmabuf_create_list) +
+		      sizeof(struct udmabuf_create_item) * NUM_ENTRIES);
+	if (!list) {
+		ksft_print_msg("%s: [FAIL, udmabuf-malloc]\n", TEST_PREFIX);
+		exit(KSFT_FAIL);
+	}
+
+	for (i = 0; i < NUM_ENTRIES; i++) {
+		list->list[i].memfd  = memfd;
+		list->list[i].offset = i * (memfd_size / NUM_ENTRIES);
+		list->list[i].size   = getpagesize() * NUM_PAGES;
+	}
+
+	list->count = NUM_ENTRIES;
+	list->flags = UDMABUF_FLAGS_CLOEXEC;
+	ubuf_fd = ioctl(devfd, UDMABUF_CREATE_LIST, list);
+	free(list);
+	if (ubuf_fd < 0) {
+		ksft_print_msg("%s: [FAIL, udmabuf-create]\n", TEST_PREFIX);
+		exit(KSFT_FAIL);
+	}
+
+	return ubuf_fd;
+}
+
+static void write_to_memfd(void *addr, off64_t size, char chr)
+{
+	int i;
+
+	for (i = 0; i < size / page_size; i++) {
+		*((char *)addr + (i * page_size)) = chr;
+	}
+}
+
+static void *mmap_fd(int fd, off64_t size)
+{
+	void *addr;
+
+	addr = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+	if (addr == MAP_FAILED) {
+		ksft_print_msg("%s: ubuf_fd mmap fail\n", TEST_PREFIX);
+		exit(KSFT_FAIL);
+	}
+
+	return addr;
+}
+
+static int compare_chunks(void *addr1, void *addr2, off64_t memfd_size)
+{
+	off64_t off;
+	int i = 0, j, k = 0, ret = 0;
+	char char1, char2;
+
+	while (i < NUM_ENTRIES) {
+		off = i * (memfd_size / NUM_ENTRIES);
+		for (j = 0; j < NUM_PAGES; j++, k++) {
+			char1 = *((char *)addr1 + off + (j * getpagesize()));
+			char2 = *((char *)addr2 + (k * getpagesize()));
+			if (char1 != char2) {
+				ret = -1;
+				goto err;
+			}
+		}
+		i++;
+	}
+err:
+	munmap(addr1, memfd_size);
+	munmap(addr2, NUM_ENTRIES * NUM_PAGES * getpagesize());
+	return ret;
 }
 
 int main(int argc, char *argv[])
 {
 	struct udmabuf_create create;
 	int devfd, memfd, buf, ret;
-	off_t size;
-	void *mem;
+	off64_t size;
+	void *addr1, *addr2;
+
+	ksft_print_header();
+	ksft_set_plan(6);
 
 	devfd = open("/dev/udmabuf", O_RDWR);
 	if (devfd < 0) {
-		printf("%s: [skip,no-udmabuf: Unable to access DMA buffer device file]\n",
-		       TEST_PREFIX);
-		exit(77);
+		ksft_print_msg(
+			"%s: [skip,no-udmabuf: Unable to access DMA buffer device file]\n",
+			TEST_PREFIX);
+		exit(KSFT_SKIP);
 	}
 
 	memfd = memfd_create("udmabuf-test", MFD_ALLOW_SEALING);
 	if (memfd < 0) {
-		printf("%s: [skip,no-memfd]\n", TEST_PREFIX);
-		exit(77);
+		ksft_print_msg("%s: [skip,no-memfd]\n", TEST_PREFIX);
+		exit(KSFT_SKIP);
 	}
 
 	ret = fcntl(memfd, F_ADD_SEALS, F_SEAL_SHRINK);
 	if (ret < 0) {
-		printf("%s: [skip,fcntl-add-seals]\n", TEST_PREFIX);
-		exit(77);
+		ksft_print_msg("%s: [skip,fcntl-add-seals]\n", TEST_PREFIX);
+		exit(KSFT_SKIP);
 	}
-
 
 	size = getpagesize() * NUM_PAGES;
 	ret = ftruncate(memfd, size);
 	if (ret == -1) {
-		printf("%s: [FAIL,memfd-truncate]\n", TEST_PREFIX);
-		exit(1);
+		ksft_print_msg("%s: [FAIL,memfd-truncate]\n", TEST_PREFIX);
+		exit(KSFT_FAIL);
 	}
 
 	memset(&create, 0, sizeof(create));
···
 	create.offset = getpagesize()/2;
 	create.size   = getpagesize();
 	buf = ioctl(devfd, UDMABUF_CREATE, &create);
-	if (buf >= 0) {
-		printf("%s: [FAIL,test-1]\n", TEST_PREFIX);
-		exit(1);
-	}
+	if (buf >= 0)
+		ksft_test_result_fail("%s: [FAIL,test-1]\n", TEST_PREFIX);
+	else
+		ksft_test_result_pass("%s: [PASS,test-1]\n", TEST_PREFIX);
 
 	/* should fail (size not multiple of page) */
 	create.memfd  = memfd;
 	create.offset = 0;
 	create.size   = getpagesize()/2;
 	buf = ioctl(devfd, UDMABUF_CREATE, &create);
-	if (buf >= 0) {
-		printf("%s: [FAIL,test-2]\n", TEST_PREFIX);
-		exit(1);
-	}
+	if (buf >= 0)
+		ksft_test_result_fail("%s: [FAIL,test-2]\n", TEST_PREFIX);
+	else
+		ksft_test_result_pass("%s: [PASS,test-2]\n", TEST_PREFIX);
 
 	/* should fail (not memfd) */
 	create.memfd  = 0; /* stdin */
 	create.offset = 0;
 	create.size   = size;
 	buf = ioctl(devfd, UDMABUF_CREATE, &create);
-	if (buf >= 0) {
-		printf("%s: [FAIL,test-3]\n", TEST_PREFIX);
-		exit(1);
-	}
+	if (buf >= 0)
+		ksft_test_result_fail("%s: [FAIL,test-3]\n", TEST_PREFIX);
+	else
+		ksft_test_result_pass("%s: [PASS,test-3]\n", TEST_PREFIX);
 
 	/* should work */
+	page_size = getpagesize();
+	addr1 = mmap_fd(memfd, size);
+	write_to_memfd(addr1, size, 'a');
 	create.memfd  = memfd;
 	create.offset = 0;
 	create.size   = size;
 	buf = ioctl(devfd, UDMABUF_CREATE, &create);
-	if (buf < 0) {
-		printf("%s: [FAIL,test-4]\n", TEST_PREFIX);
-		exit(1);
-	}
+	if (buf < 0)
+		ksft_test_result_fail("%s: [FAIL,test-4]\n", TEST_PREFIX);
+	else
+		ksft_test_result_pass("%s: [PASS,test-4]\n", TEST_PREFIX);
 
-	fprintf(stderr, "%s: ok\n", TEST_PREFIX);
+	munmap(addr1, size);
+	close(buf);
+	close(memfd);
+
+	/* should work (migration of 4k size pages)*/
+	size = MEMFD_SIZE * page_size;
+	memfd = create_memfd_with_seals(size, false);
+	addr1 = mmap_fd(memfd, size);
+	write_to_memfd(addr1, size, 'a');
+	buf = create_udmabuf_list(devfd, memfd, size);
+	addr2 = mmap_fd(buf, NUM_PAGES * NUM_ENTRIES * getpagesize());
+	write_to_memfd(addr1, size, 'b');
+	ret = compare_chunks(addr1, addr2, size);
+	if (ret < 0)
+		ksft_test_result_fail("%s: [FAIL,test-5]\n", TEST_PREFIX);
+	else
+		ksft_test_result_pass("%s: [PASS,test-5]\n", TEST_PREFIX);
+
+	close(buf);
+	close(memfd);
+
+	/* should work (migration of 2MB size huge pages)*/
+	page_size = getpagesize() * 512; /* 2 MB */
+	size = MEMFD_SIZE * page_size;
+	memfd = create_memfd_with_seals(size, true);
+	addr1 = mmap_fd(memfd, size);
+	write_to_memfd(addr1, size, 'a');
+	buf = create_udmabuf_list(devfd, memfd, size);
+	addr2 = mmap_fd(buf, NUM_PAGES * NUM_ENTRIES * getpagesize());
+	write_to_memfd(addr1, size, 'b');
+	ret = compare_chunks(addr1, addr2, size);
+	if (ret < 0)
+		ksft_test_result_fail("%s: [FAIL,test-6]\n", TEST_PREFIX);
+	else
+		ksft_test_result_pass("%s: [PASS,test-6]\n", TEST_PREFIX);
+
 	close(buf);
 	close(memfd);
 	close(devfd);
+
+	ksft_print_msg("%s: ok\n", TEST_PREFIX);
+	ksft_print_cnts();
+
 	return 0;
 }