[Intel-gfx] [PATCH i-g-t v2] tests/drv_hangman: test for acthd increasing through invalid VM space

[Chris Wilson]

On Thu, Feb 25, 2016 at 10:32:11AM +0000, daniele.ceraolospurio at intel.com wrote:
> +/* This test covers the case where we end up in an uninitialised area of the
> + * ppgtt at an offset greater than the one where the last buffer is mapped. This
> + * is particularly relevant if 48b ppgtt is enabled because the ppgtt is
> + * massively bigger compared to the 32b case and it takes a lot more time to
> + * wrap, so the acthd can potentially keep increasing for a long time
> + */
> +#define NSEC_PER_SEC	1000000000L
> +static void ppgtt_walking(void)
> +{
> +	int fd;
> +	int64_t timeout_ns = 100 * NSEC_PER_SEC; /* 100 seconds */

This needs a note that this has to be greater than ~5*hangcheck.

> +	struct drm_i915_gem_execbuffer2 execbuf;
> +	struct drm_i915_gem_exec_object2 gem_exec;
> +	uint32_t handle;
> +	uint32_t batch[4];
> +
> +	fd = drm_open_driver(DRIVER_INTEL);
> +	igt_require(gem_gtt_type(fd) > 2);

Nope, just full-ppgtt is required (and provides a sensible hangcheck
test if !48bit as well).

Note this does require that the hangcheck is enabled, so igt_require().

> +
> +	/* the batch will be mapped to an offset < 4GB because the flag to allow
> +	 * 48b offsets is not specified, so jump to address 0x00000001 00000000
> +	 */
> +	batch[0] = MI_BATCH_BUFFER_START | 1;
> +	batch[1] = 0;
> +	batch[2] = 1;
> +	batch[3] = MI_BATCH_BUFFER_END;

The vm is entirely empty. Just submit an unterminated (empty) batch, and
it will walk from 0 to 1<<48bit and around and around and around and
around...

> +
> +	handle = gem_create(fd, 4096);
> +	gem_write(fd, handle, 0, batch, sizeof(batch));
> +
> +	memset(&gem_exec, 0, sizeof(gem_exec));
> +	gem_exec.handle = handle;
> +
> +	memset(&execbuf, 0, sizeof(execbuf));
> +	execbuf.buffers_ptr = (uintptr_t)&gem_exec;
> +	execbuf.buffer_count = 1;
> +	execbuf.batch_len = 16;
> +
> +	gem_execbuf(fd, &execbuf);
> +
> +	igt_assert(gem_wait(fd, handle, &timeout_ns) == 0);

igt_assert_eq(gem_wait(), 0); so you get the information about the
failure.

> +	igt_assert(timeout_ns > 0);

Redundant. gem_wait() returns ETIME if we wait for timeout_ns without
completion.

> +
> +	gem_close(fd, handle);

Irrelevant, it will be closed with close(fd).

> +	close(fd);
> +}
> +
>  igt_main
>  {
>  	const struct intel_execution_engine *e;
> @@ -314,4 +361,7 @@ igt_main
>  			test_error_state_capture(e->exec_id | e->flags,
>  						 e->full_name);
>  	}
> +
> +	igt_subtest("ppgtt-walking")
> +		ppgtt_walking();

This is a hangcheck test, "hangcheck-unterminated"
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre