Re: [Intel-gfx] [PATCH 3/5] drm/i915: Add live selftests for indirect ctx batchbuffers

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Mika Kuoppala <mika.kuoppala@linux.intel.com> writes:

> Indirect ctx batchbuffers are a hw feature of which
> batch can be run, by hardware, during context restoration stage.
> Driver can setup a batchbuffer and also an offset into the
> context image. When context image is marshalled from
> memory to registers, and when the offset from the start of
> context register state is equal of what driver pre-determined,
> batch will run. So one can manipulate context restoration
> process at any granularity of one lri, given some

This is wrong, it is granularity of cacheline.
-Mika

> limitations, as you need to have rudimentaries in place
> before you can run a batch.
>
> Add selftest which will write the ring start register
> to a canary spot. This will test that hardware will run a
> batchbuffer for the context in question.
>
> Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/gt/selftest_lrc.c | 156 ++++++++++++++++++++++++-
>  1 file changed, 155 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c b/drivers/gpu/drm/i915/gt/selftest_lrc.c
> index 32d2b0850dec..32c4096b627b 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c
> @@ -5363,6 +5363,159 @@ static int live_lrc_isolation(void *arg)
>  	return err;
>  }
>  
> +static int ctx_bb_submit_req(struct intel_context *ce)
> +{
> +	struct i915_request *rq;
> +	int err;
> +
> +	rq = intel_context_create_request(ce);
> +	if (IS_ERR(rq))
> +		return PTR_ERR(rq);
> +
> +	i915_request_get(rq);
> +	i915_request_add(rq);
> +
> +	err = i915_request_wait(rq, 0, HZ / 5);
> +	if (err < 0)
> +		pr_err("%s: request not completed!\n", rq->engine->name);
> +
> +	i915_request_put(rq);
> +
> +	return 0;
> +}
> +
> +#define CTX_BB_CANARY_OFFSET (3*1024)
> +#define CTX_BB_CANARY_INDEX  (CTX_BB_CANARY_OFFSET/sizeof(u32))
> +
> +static u32 *
> +emit_ctx_bb_canary(struct intel_context *ce, u32 *cs)
> +{
> +	const u32 ring_start_reg = i915_mmio_reg_offset(RING_START(0));
> +	const u32 srm = MI_STORE_REGISTER_MEM_GEN8 |
> +		MI_SRM_LRM_GLOBAL_GTT | MI_LRI_LRM_CS_MMIO;
> +
> +	*cs++ = srm;
> +	*cs++ = ring_start_reg;
> +	*cs++ = i915_ggtt_offset(ce->state) +
> +		ce->ctx_bb_offset + CTX_BB_CANARY_OFFSET;
> +	*cs++ = 0;
> +
> +	return cs;
> +}
> +
> +static void
> +ctx_bb_setup(struct intel_context *ce)
> +{
> +	u32 *cs = context_indirect_bb(ce);
> +
> +	cs[CTX_BB_CANARY_INDEX] = 0xdeadf00d;
> +
> +	setup_indirect_ctx_bb(ce, emit_ctx_bb_canary);
> +}
> +
> +static bool check_ring_start(struct intel_context *ce)
> +{
> +	const u32 * const ctx_bb = (void *)(ce->lrc_reg_state) -
> +		LRC_STATE_PN * PAGE_SIZE + ce->ctx_bb_offset;
> +
> +	if (ctx_bb[CTX_BB_CANARY_INDEX] == ce->lrc_reg_state[CTX_RING_START])
> +		return true;
> +
> +	pr_err("ring start mismatch: canary 0x%08x vs state 0x%08x\n",
> +	       ctx_bb[CTX_BB_CANARY_INDEX],
> +	       ce->lrc_reg_state[CTX_RING_START]);
> +
> +	return false;
> +}
> +
> +static int ctx_bb_check(struct intel_context *ce)
> +{
> +	int err;
> +
> +	err = ctx_bb_submit_req(ce);
> +	if (err)
> +		return err;
> +
> +	if (!check_ring_start(ce))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int __per_ctx_bb(struct intel_engine_cs *engine)
> +{
> +	struct intel_context *ce1, *ce2;
> +	int err = 0;
> +
> +	ce1 = intel_context_create(engine);
> +	ce2 = intel_context_create(engine);
> +
> +	err = intel_context_pin(ce1);
> +	if (err)
> +		return err;
> +
> +	err = intel_context_pin(ce2);
> +	if (err) {
> +		intel_context_put(ce1);
> +		return err;
> +	}
> +
> +	/* We use the already reserved extra page in context state */
> +	if (!ce1->ctx_bb_offset) {
> +		GEM_BUG_ON(ce2->ctx_bb_offset);
> +		GEM_BUG_ON(INTEL_GEN(engine->i915) == 12);
> +		goto out;
> +	}
> +
> +	/* In order to test that our per context bb is truly per context,
> +	 * and executes at the intended spot on context restoring process,
> +	 * make the batch store the ring start value to memory.
> +	 * As ring start is restored apriori of starting the indirect ctx bb and
> +	 * as it will be different for each context, it fits to this purpose.
> +	 */
> +	ctx_bb_setup(ce1);
> +	ctx_bb_setup(ce2);
> +
> +	err = ctx_bb_check(ce1);
> +	if (err)
> +		goto out;
> +
> +	err = ctx_bb_check(ce2);
> +out:
> +	intel_context_unpin(ce2);
> +	intel_context_put(ce2);
> +
> +	intel_context_unpin(ce1);
> +	intel_context_put(ce1);
> +
> +	return err;
> +}
> +
> +static int live_lrc_indirect_ctx_bb(void *arg)
> +{
> +	struct intel_gt *gt = arg;
> +	struct intel_engine_cs *engine;
> +	enum intel_engine_id id;
> +	int err = 0;
> +
> +	for_each_engine(engine, gt, id) {
> +
> +		intel_engine_pm_get(engine);
> +		err = __per_ctx_bb(engine);
> +		intel_engine_pm_put(engine);
> +
> +		if (err)
> +			break;
> +
> +		if (igt_flush_test(gt->i915)) {
> +			err = -EIO;
> +			break;
> +		}
> +	}
> +
> +	return err;
> +}
> +
>  static void garbage_reset(struct intel_engine_cs *engine,
>  			  struct i915_request *rq)
>  {
> @@ -5594,10 +5747,11 @@ int intel_lrc_live_selftests(struct drm_i915_private *i915)
>  		SUBTEST(live_lrc_fixed),
>  		SUBTEST(live_lrc_state),
>  		SUBTEST(live_lrc_gpr),
> -		SUBTEST(live_lrc_isolation),
> +		SUBTEST(live_lrc_indirect_ctx_bb),
>  		SUBTEST(live_lrc_timestamp),
>  		SUBTEST(live_lrc_garbage),
>  		SUBTEST(live_pphwsp_runtime),
> +		SUBTEST(live_lrc_isolation),
>  	};
>  
>  	if (!HAS_LOGICAL_RING_CONTEXTS(i915))
> -- 
> 2.17.1
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