prime_mmap: Add basic tests to write in a bo using CPU

This patch adds test_correct_cpu_write, which maps the texture buffer through a
prime fd and then writes directly to it using the CPU. It stresses the driver
to guarantee cache synchronization among the different domains.

This test also adds test_forked_cpu_write, which creates the GEM bo in one
process and pass the prime handle of the it to another process, which in turn
uses the handle only to map and write. Roughly speaking this test simulates
Chrome OS  architecture, where the Web content ("unpriviledged process") maps
and CPU-draws a buffer, which was previously allocated in the GPU process
("priviledged process").

This requires kernel modifications (Daniel Thompson's "drm: prime: Honour
O_RDWR during prime-handle-to-fd") and therefore prime_handle_to_fd_for_mmap is
added to fail in case these lack. Also, upcoming tests (e.g. next patch) are
going to use it as well, so make it public and available in the lib.

v2: adds prime_handle_to_fd_with_mmap for skipping test in older kernels and
test for invalid flags.

Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>

tests/prime_mmap.c

@@ -22,6 +22,7 @@
  *
  * Authors:
  *    Rob Bradford <rob at linux.intel.com>
+ *    Tiago Vignatti <tiago.vignatti at intel.com>
  *
  */
 
@@ -65,6 +66,12 @@ fill_bo(uint32_t handle, size_t size)
 	}
 }
 
+static void
+fill_bo_cpu(char *ptr)
+{
+	memcpy(ptr, pattern, sizeof(pattern));
+}
+
 static void
 test_correct(void)
 {
@@ -180,6 +187,65 @@ test_forked(void)
 	gem_close(fd, handle);
 }
 
+/* test simple CPU write */
+static void
+test_correct_cpu_write(void)
+{
+	int dma_buf_fd;
+	char *ptr;
+	uint32_t handle;
+
+	handle = gem_create(fd, BO_SIZE);
+
+	dma_buf_fd = prime_handle_to_fd_for_mmap(fd, handle);
+
+	/* Skip if DRM_RDWR is not supported */
+	igt_skip_on(errno == EINVAL);
+
+	/* Check correctness of map using write protection (PROT_WRITE) */
+	ptr = mmap(NULL, BO_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, dma_buf_fd, 0);
+	igt_assert(ptr != MAP_FAILED);
+
+	/* Fill bo using CPU */
+	fill_bo_cpu(ptr);
+
+	/* Check pattern correctness */
+	igt_assert(memcmp(ptr, pattern, sizeof(pattern)) == 0);
+
+	munmap(ptr, BO_SIZE);
+	close(dma_buf_fd);
+	gem_close(fd, handle);
+}
+
+/* map from another process and then write using CPU */
+static void
+test_forked_cpu_write(void)
+{
+	int dma_buf_fd;
+	char *ptr;
+	uint32_t handle;
+
+	handle = gem_create(fd, BO_SIZE);
+
+	dma_buf_fd = prime_handle_to_fd_for_mmap(fd, handle);
+
+	/* Skip if DRM_RDWR is not supported */
+	igt_skip_on(errno == EINVAL);
+
+	igt_fork(childno, 1) {
+		ptr = mmap(NULL, BO_SIZE, PROT_READ | PROT_WRITE , MAP_SHARED, dma_buf_fd, 0);
+		igt_assert(ptr != MAP_FAILED);
+		fill_bo_cpu(ptr);
+
+		igt_assert(memcmp(ptr, pattern, sizeof(pattern)) == 0);
+		munmap(ptr, BO_SIZE);
+		close(dma_buf_fd);
+	}
+	close(dma_buf_fd);
+	igt_waitchildren();
+	gem_close(fd, handle);
+}
+
 static void
 test_refcounting(void)
 {
@@ -224,15 +290,14 @@ test_dup(void)
 	close (dma_buf_fd);
 }
 
-
 /* Used for error case testing to avoid wrapper */
-static int prime_handle_to_fd_no_assert(uint32_t handle, int *fd_out)
+static int prime_handle_to_fd_no_assert(uint32_t handle, int flags, int *fd_out)
 {
 	struct drm_prime_handle args;
 	int ret;
 
 	args.handle = handle;
-	args.flags = DRM_CLOEXEC;
+	args.flags = flags;
 	args.fd = -1;
 
 	ret = drmIoctl(fd, DRM_IOCTL_PRIME_HANDLE_TO_FD, &args);
@@ -260,7 +325,7 @@ test_userptr(void)
 	gem_userptr(fd, (uint32_t *)ptr, BO_SIZE, 0, 0, &handle);
 
 	/* export userptr */
-	ret = prime_handle_to_fd_no_assert(handle, &dma_buf_fd);
+	ret = prime_handle_to_fd_no_assert(handle, DRM_CLOEXEC, &dma_buf_fd);
 	if (ret) {
 		igt_assert(ret == EINVAL || ret == ENODEV);
 		goto free_userptr;
@@ -281,15 +346,25 @@ free_userptr:
 static void
 test_errors(void)
 {
-	int dma_buf_fd;
+	int i, dma_buf_fd;
 	char *ptr;
 	uint32_t handle;
+	int invalid_flags[] = {DRM_CLOEXEC - 1, DRM_CLOEXEC + 1,
+	                       DRM_RDWR - 1, DRM_RDWR + 1};
+
+	/* Test for invalid flags */
+	handle = gem_create(fd, BO_SIZE);
+	for (i = 0; i < sizeof(invalid_flags) / sizeof(invalid_flags[0]); i++) {
+		prime_handle_to_fd_no_assert(handle, invalid_flags[i], &dma_buf_fd);
+		igt_assert_eq(errno, EINVAL);
+		errno = 0;
+	}
 
 	/* Close gem object before priming */
 	handle = gem_create(fd, BO_SIZE);
 	fill_bo(handle, BO_SIZE);
 	gem_close(fd, handle);
-	prime_handle_to_fd_no_assert(handle, &dma_buf_fd);
+	prime_handle_to_fd_no_assert(handle, DRM_CLOEXEC, &dma_buf_fd);
 	igt_assert(dma_buf_fd == -1 && errno == ENOENT);
 	errno = 0;
 
@@ -392,6 +467,8 @@ igt_main
 		{ "test_map_unmap", test_map_unmap },
 		{ "test_reprime", test_reprime },
 		{ "test_forked", test_forked },
+		{ "test_correct_cpu_write", test_correct_cpu_write },
+		{ "test_forked_cpu_write", test_forked_cpu_write },
 		{ "test_refcounting", test_refcounting },
 		{ "test_dup", test_dup },
 		{ "test_userptr", test_userptr },