Commit 9199c070 authored by Chris Wilson's avatar Chris Wilson

drm/i915/selftests: Exercise far preemption rollbacks

Not too long ago, we realised we had issues with a rolling back a
context so far for a preemption request we considered the resubmit not
to be a rollback but a forward roll. This means we would issue a lite
restore instead of forcing a full restore, continuing execution of the
old requests rather than causing a preemption. Add a selftest to
exercise such a far rollback, such that if we were to skip the full
restore, we would execute invalid instructions in the ring and hang.

Note that while I was able to confirm that this causes us to do a
lite-restore preemption rollback (with commit e36ba817 ("drm/i915/gt:
Incrementally check for rewinding") disabled), it did not trick the HW
into rolling past the old RING_TAIL. Myybe on other HW.

References: e36ba817 ("drm/i915/gt: Incrementally check for rewinding")
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200616185518.11948-1-chris@chris-wilson.co.uk
parent 223128f7
...@@ -363,6 +363,156 @@ static int live_unlite_preempt(void *arg) ...@@ -363,6 +363,156 @@ static int live_unlite_preempt(void *arg)
return live_unlite_restore(arg, I915_USER_PRIORITY(I915_PRIORITY_MAX)); return live_unlite_restore(arg, I915_USER_PRIORITY(I915_PRIORITY_MAX));
} }
static int live_unlite_ring(void *arg)
{
struct intel_gt *gt = arg;
struct intel_engine_cs *engine;
struct igt_spinner spin;
enum intel_engine_id id;
int err = 0;
/*
* Setup a preemption event that will cause almost the entire ring
* to be unwound, potentially fooling our intel_ring_direction()
* into emitting a forward lite-restore instead of the rollback.
*/
if (igt_spinner_init(&spin, gt))
return -ENOMEM;
for_each_engine(engine, gt, id) {
struct intel_context *ce[2] = {};
struct i915_request *rq;
struct igt_live_test t;
int n;
if (!intel_engine_has_preemption(engine))
continue;
if (!intel_engine_can_store_dword(engine))
continue;
if (igt_live_test_begin(&t, gt->i915, __func__, engine->name)) {
err = -EIO;
break;
}
engine_heartbeat_disable(engine);
for (n = 0; n < ARRAY_SIZE(ce); n++) {
struct intel_context *tmp;
tmp = intel_context_create(engine);
if (IS_ERR(tmp)) {
err = PTR_ERR(tmp);
goto err_ce;
}
err = intel_context_pin(tmp);
if (err) {
intel_context_put(tmp);
goto err_ce;
}
memset32(tmp->ring->vaddr,
0xdeadbeef, /* trigger a hang if executed */
tmp->ring->vma->size / sizeof(u32));
ce[n] = tmp;
}
/* Create max prio spinner, followed by N low prio nops */
rq = igt_spinner_create_request(&spin, ce[0], MI_ARB_CHECK);
if (IS_ERR(rq)) {
err = PTR_ERR(rq);
goto err_ce;
}
i915_request_get(rq);
rq->sched.attr.priority = I915_PRIORITY_BARRIER;
i915_request_add(rq);
if (!igt_wait_for_spinner(&spin, rq)) {
intel_gt_set_wedged(gt);
i915_request_put(rq);
err = -ETIME;
goto err_ce;
}
/* Fill the ring, until we will cause a wrap */
n = 0;
while (intel_ring_direction(ce[0]->ring,
rq->wa_tail,
ce[0]->ring->tail) <= 0) {
struct i915_request *tmp;
tmp = intel_context_create_request(ce[0]);
if (IS_ERR(tmp)) {
err = PTR_ERR(tmp);
i915_request_put(rq);
goto err_ce;
}
i915_request_add(tmp);
intel_engine_flush_submission(engine);
n++;
}
intel_engine_flush_submission(engine);
pr_debug("%s: Filled ring with %d nop tails {size:%x, tail:%x, emit:%x, rq.tail:%x}\n",
engine->name, n,
ce[0]->ring->size,
ce[0]->ring->tail,
ce[0]->ring->emit,
rq->tail);
GEM_BUG_ON(intel_ring_direction(ce[0]->ring,
rq->tail,
ce[0]->ring->tail) <= 0);
i915_request_put(rq);
/* Create a second ring to preempt the first ring after rq[0] */
rq = intel_context_create_request(ce[1]);
if (IS_ERR(rq)) {
err = PTR_ERR(rq);
goto err_ce;
}
rq->sched.attr.priority = I915_PRIORITY_BARRIER;
i915_request_get(rq);
i915_request_add(rq);
err = wait_for_submit(engine, rq, HZ / 2);
i915_request_put(rq);
if (err) {
pr_err("%s: preemption request was not submited\n",
engine->name);
err = -ETIME;
}
pr_debug("%s: ring[0]:{ tail:%x, emit:%x }, ring[1]:{ tail:%x, emit:%x }\n",
engine->name,
ce[0]->ring->tail, ce[0]->ring->emit,
ce[1]->ring->tail, ce[1]->ring->emit);
err_ce:
intel_engine_flush_submission(engine);
igt_spinner_end(&spin);
for (n = 0; n < ARRAY_SIZE(ce); n++) {
if (IS_ERR_OR_NULL(ce[n]))
break;
intel_context_unpin(ce[n]);
intel_context_put(ce[n]);
}
engine_heartbeat_enable(engine);
if (igt_live_test_end(&t))
err = -EIO;
if (err)
break;
}
igt_spinner_fini(&spin);
return err;
}
static int live_pin_rewind(void *arg) static int live_pin_rewind(void *arg)
{ {
struct intel_gt *gt = arg; struct intel_gt *gt = arg;
...@@ -4374,6 +4524,7 @@ int intel_execlists_live_selftests(struct drm_i915_private *i915) ...@@ -4374,6 +4524,7 @@ int intel_execlists_live_selftests(struct drm_i915_private *i915)
SUBTEST(live_sanitycheck), SUBTEST(live_sanitycheck),
SUBTEST(live_unlite_switch), SUBTEST(live_unlite_switch),
SUBTEST(live_unlite_preempt), SUBTEST(live_unlite_preempt),
SUBTEST(live_unlite_ring),
SUBTEST(live_pin_rewind), SUBTEST(live_pin_rewind),
SUBTEST(live_hold_reset), SUBTEST(live_hold_reset),
SUBTEST(live_error_interrupt), SUBTEST(live_error_interrupt),
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment