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

[Daniele Ceraolo Spurio]

On 25/02/16 10:41, Chris Wilson wrote:
> 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...

I chose to jump instead of just leaving the batch unterminated to cover 
the (rare) case where the rest of the allocated 4k of the batch contain 
some random values, which could cause a hang and thus falsely pass the 
test. I'll respin with a memset to 0 of the batch (plus all the other 
suggested changes).

Thanks,
Daniele

>
>> +
>> +	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
>