[Intel-gfx] [PATCH 1/2] tests/gem_exec_parse: fix batch_len setting for cmd-crossing-page

[bradley.d.volkin at intel.com]

From: Brad Volkin <bradley.d.volkin at intel.com>

The size of the batch buffer passed to the kernel is significantly
larger than the size of the batch buffer passed to the function. A
proposed optimization as part of the batch copy kernel series is to
use batch_len for the copy and parse operations, which leads to a
false "batch without MI_BATCH_BUFFER_END" failure for this test.

To fix this, modify the test to set batch_start_offset and batch_len
such that they define the range of actual commands in the batch,
including a few of the surrounding nops for alignment purposes.

v2: update batch_start_offset as well

Signed-off-by: Brad Volkin <bradley.d.volkin at intel.com>
---
 tests/gem_exec_parse.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/tests/gem_exec_parse.c b/tests/gem_exec_parse.c
index 1dc9103..e48b83a 100644
--- a/tests/gem_exec_parse.c
+++ b/tests/gem_exec_parse.c
@@ -144,16 +144,18 @@ static void exec_split_batch(int fd, uint32_t *cmds,
 	struct drm_i915_gem_exec_object2 objs[1];
 	uint32_t cmd_bo;
 	uint32_t noop[1024] = { 0 };
+	const int alloc_size = 4096 * 2;
+	const int actual_start_offset = 4096-sizeof(uint32_t);
 
 	// Allocate and fill a 2-page batch with noops
-	cmd_bo = gem_create(fd, 4096 * 2);
+	cmd_bo = gem_create(fd, alloc_size);
 	gem_write(fd, cmd_bo, 0, noop, sizeof(noop));
 	gem_write(fd, cmd_bo, 4096, noop, sizeof(noop));
 
 	// Write the provided commands such that the first dword
 	// of the command buffer is the last dword of the first
 	// page (i.e. the command is split across the two pages).
-	gem_write(fd, cmd_bo, 4096-sizeof(uint32_t), cmds, size);
+	gem_write(fd, cmd_bo, actual_start_offset, cmds, size);
 
 	objs[0].handle = cmd_bo;
 	objs[0].relocation_count = 0;
@@ -166,8 +168,14 @@ static void exec_split_batch(int fd, uint32_t *cmds,
 
 	execbuf.buffers_ptr = (uintptr_t)objs;
 	execbuf.buffer_count = 1;
-	execbuf.batch_start_offset = 0;
-	execbuf.batch_len = size;
+	// NB: We want batch_start_offset and batch_len to point to the block
+	// of the actual commands (i.e. at the last dword of the first page),
+	// but have to adjust both the start offset and length to meet the
+	// kernel driver's requirements on the alignment of those fields.
+	execbuf.batch_start_offset = actual_start_offset & ~0x7;
+	execbuf.batch_len =
+		ALIGN(size + actual_start_offset - execbuf.batch_start_offset,
+		      0x8);
 	execbuf.cliprects_ptr = 0;
 	execbuf.num_cliprects = 0;
 	execbuf.DR1 = 0;
-- 
1.9.1