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drm/i915/selftests: Sabotague the RING_HEAD

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Apply vast quantities of poison and not tell anyone to see if we fall
for the trap of using a stale RING_HEAD.

References: 42827350f7 ("drm/i915/gt: Avoid resetting ring->head outside of its timeline mutex")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200211205615.1190127-2-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson
2020-02-11 20:56:15 +00:00
parent 89dd019a8a
commit 37305ede63
1 changed files with 79 additions and 0 deletions
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79
drivers/gpu/drm/i915/gt/selftest_lrc.c
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@ -300,6 +300,84 @@ static int live_unlite_preempt(void *arg)
return live_unlite_restore(arg, I915_USER_PRIORITY(I915_PRIORITY_MAX));
}
static int live_pin_rewind(void *arg)
{
struct intel_gt *gt = arg;
struct intel_engine_cs *engine;
enum intel_engine_id id;
int err = 0;
/*
* We have to be careful not to trust intel_ring too much, for example
* ring->head is updated upon retire which is out of sync with pinning
* the context. Thus we cannot use ring->head to set CTX_RING_HEAD,
* or else we risk writing an older, stale value.
*
* To simulate this, let's apply a bit of deliberate sabotague.
*/
for_each_engine(engine, gt, id) {
struct intel_context *ce;
struct i915_request *rq;
struct intel_ring *ring;
struct igt_live_test t;
if (igt_live_test_begin(&t, gt->i915, __func__, engine->name)) {
err = -EIO;
break;
}
ce = intel_context_create(engine);
if (IS_ERR(ce)) {
err = PTR_ERR(ce);
break;
}
err = intel_context_pin(ce);
if (err) {
intel_context_put(ce);
break;
}
/* Keep the context awake while we play games */
err = i915_active_acquire(&ce->active);
if (err) {
intel_context_unpin(ce);
intel_context_put(ce);
break;
}
ring = ce->ring;
/* Poison the ring, and offset the next request from HEAD */
memset32(ring->vaddr, STACK_MAGIC, ring->size / sizeof(u32));
ring->emit = ring->size / 2;
ring->tail = ring->emit;
GEM_BUG_ON(ring->head);
intel_context_unpin(ce);
/* Submit a simple nop request */
GEM_BUG_ON(intel_context_is_pinned(ce));
rq = intel_context_create_request(ce);
i915_active_release(&ce->active); /* e.g. async retire */
intel_context_put(ce);
if (IS_ERR(rq)) {
err = PTR_ERR(rq);
break;
}
GEM_BUG_ON(!rq->head);
i915_request_add(rq);
/* Expect not to hang! */
if (igt_live_test_end(&t)) {
err = -EIO;
break;
}
}
return err;
}
static int live_hold_reset(void *arg)
{
struct intel_gt *gt = arg;
@ -3629,6 +3707,7 @@ int intel_execlists_live_selftests(struct drm_i915_private *i915)
SUBTEST(live_sanitycheck),
SUBTEST(live_unlite_switch),
SUBTEST(live_unlite_preempt),
SUBTEST(live_pin_rewind),
SUBTEST(live_hold_reset),
SUBTEST(live_error_interrupt),
SUBTEST(live_timeslice_preempt),