We manipulate ring->head while active in i915_request_retire underneath the timeline manipulation. We cannot rely on a stable ring->head outside of the timeline->mutex, in particular while setting up the context for resume and reset.
Closes: https://gitlab.freedesktop.org/drm/intel/issues/1126 Fixes: 0881954965e3 ("drm/i915: Introduce intel_context.pin_mutex for pin management") Fixes: e5dadff4b093 ("drm/i915: Protect request retirement with timeline->mutex") References: f3c0efc9fe7a ("drm/i915/execlists: Leave resetting ring to intel_ring") Signed-off-by: Chris Wilson <[email protected]> Cc: Matthew Auld <[email protected]> Cc: Tvrtko Ursulin <[email protected]> Cc: Mika Kuoppala <[email protected]> --- drivers/gpu/drm/i915/gt/intel_lrc.c | 36 ++++++++++++-------------- drivers/gpu/drm/i915/gt/selftest_lrc.c | 2 +- 2 files changed, 18 insertions(+), 20 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c index 929be03bbe7e..70d91ad923ef 100644 --- a/drivers/gpu/drm/i915/gt/intel_lrc.c +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c @@ -235,7 +235,8 @@ static void execlists_init_reg_state(u32 *reg_state, bool close); static void __execlists_update_reg_state(const struct intel_context *ce, - const struct intel_engine_cs *engine); + const struct intel_engine_cs *engine, + u32 head); static void mark_eio(struct i915_request *rq) { @@ -1184,12 +1185,11 @@ static void reset_active(struct i915_request *rq, head = rq->tail; else head = active_request(ce->timeline, rq)->head; - ce->ring->head = intel_ring_wrap(ce->ring, head); - intel_ring_update_space(ce->ring); + head = intel_ring_wrap(ce->ring, head); /* Scrub the context image to prevent replaying the previous batch */ restore_default_state(ce, engine); - __execlists_update_reg_state(ce, engine); + __execlists_update_reg_state(ce, engine, head); /* We've switched away, so this should be a no-op, but intent matters */ ce->lrc_desc |= CTX_DESC_FORCE_RESTORE; @@ -2878,16 +2878,17 @@ static void execlists_context_unpin(struct intel_context *ce) static void __execlists_update_reg_state(const struct intel_context *ce, - const struct intel_engine_cs *engine) + const struct intel_engine_cs *engine, + u32 head) { struct intel_ring *ring = ce->ring; u32 *regs = ce->lrc_reg_state; - GEM_BUG_ON(!intel_ring_offset_valid(ring, ring->head)); + GEM_BUG_ON(!intel_ring_offset_valid(ring, head)); GEM_BUG_ON(!intel_ring_offset_valid(ring, ring->tail)); regs[CTX_RING_START] = i915_ggtt_offset(ring->vma); - regs[CTX_RING_HEAD] = ring->head; + regs[CTX_RING_HEAD] = head; regs[CTX_RING_TAIL] = ring->tail; /* RPCS */ @@ -2916,7 +2917,7 @@ __execlists_context_pin(struct intel_context *ce, ce->lrc_desc = lrc_descriptor(ce, engine) | CTX_DESC_FORCE_RESTORE; ce->lrc_reg_state = vaddr + LRC_STATE_PN * PAGE_SIZE; - __execlists_update_reg_state(ce, engine); + __execlists_update_reg_state(ce, engine, ce->ring->tail); return 0; } @@ -2941,7 +2942,7 @@ static void execlists_context_reset(struct intel_context *ce) /* Scrub away the garbage */ execlists_init_reg_state(ce->lrc_reg_state, ce, ce->engine, ce->ring, true); - __execlists_update_reg_state(ce, ce->engine); + __execlists_update_reg_state(ce, ce->engine, ce->ring->tail); ce->lrc_desc |= CTX_DESC_FORCE_RESTORE; } @@ -3538,6 +3539,7 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled) struct intel_engine_execlists * const execlists = &engine->execlists; struct intel_context *ce; struct i915_request *rq; + u32 head; mb(); /* paranoia: read the CSB pointers from after the reset */ clflush(execlists->csb_write); @@ -3565,15 +3567,15 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled) if (i915_request_completed(rq)) { /* Idle context; tidy up the ring so we can restart afresh */ - ce->ring->head = intel_ring_wrap(ce->ring, rq->tail); + head = intel_ring_wrap(ce->ring, rq->tail); goto out_replay; } /* Context has requests still in-flight; it should not be idle! */ GEM_BUG_ON(i915_active_is_idle(&ce->active)); rq = active_request(ce->timeline, rq); - ce->ring->head = intel_ring_wrap(ce->ring, rq->head); - GEM_BUG_ON(ce->ring->head == ce->ring->tail); + head = intel_ring_wrap(ce->ring, rq->head); + GEM_BUG_ON(head == ce->ring->tail); /* * If this request hasn't started yet, e.g. it is waiting on a @@ -3618,10 +3620,9 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled) out_replay: ENGINE_TRACE(engine, "replay {head:%04x, tail:%04x}\n", - ce->ring->head, ce->ring->tail); - intel_ring_update_space(ce->ring); + head, ce->ring->tail); __execlists_reset_reg_state(ce, engine); - __execlists_update_reg_state(ce, engine); + __execlists_update_reg_state(ce, engine, head); ce->lrc_desc |= CTX_DESC_FORCE_RESTORE; /* paranoid: GPU was reset! */ unwind: @@ -5265,10 +5266,7 @@ void intel_lr_context_reset(struct intel_engine_cs *engine, restore_default_state(ce, engine); /* Rerun the request; its payload has been neutered (if guilty). */ - ce->ring->head = head; - intel_ring_update_space(ce->ring); - - __execlists_update_reg_state(ce, engine); + __execlists_update_reg_state(ce, engine, head); } bool diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c b/drivers/gpu/drm/i915/gt/selftest_lrc.c index 7ef68500b2bd..82fa0712808e 100644 --- a/drivers/gpu/drm/i915/gt/selftest_lrc.c +++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c @@ -201,7 +201,7 @@ static int live_unlite_restore(struct intel_gt *gt, int prio) } GEM_BUG_ON(!ce[1]->ring->size); intel_ring_reset(ce[1]->ring, ce[1]->ring->size / 2); - __execlists_update_reg_state(ce[1], engine); + __execlists_update_reg_state(ce[1], engine, ce[1]->ring->head); rq[0] = igt_spinner_create_request(&spin, ce[0], MI_ARB_CHECK); if (IS_ERR(rq[0])) { -- 2.25.0 _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
