From: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
To: Matthew Brost <matthew.brost@intel.com>,
<intel-gfx@lists.freedesktop.org>,
<dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH 06/27] drm/i915/guc: Workaround reset G2H is received after schedule done G2H
Date: Thu, 26 Aug 2021 16:11:41 -0700 [thread overview]
Message-ID: <515e2439-46d4-8e80-f07b-c862a123d836@intel.com> (raw)
In-Reply-To: <20210826032327.18078-7-matthew.brost@intel.com>
On 8/25/2021 8:23 PM, Matthew Brost wrote:
> If the context is reset as a result of the request cancellation the
> context reset G2H is received after schedule disable done G2H which is
> the wrong order. The schedule disable done G2H release the waiting
> request cancellation code which resubmits the context. This races
> with the context reset G2H which also wants to resubmit the context but
> in this case it really should be a NOP as request cancellation code owns
> the resubmit. Use some clever tricks of checking the context state to
> seal this race until the GuC firmware is fixed.
>
> v2:
> (Checkpatch)
> - Fix typos
> v3:
> (Daniele)
> - State that is a bug in the GuC firmware
>
> Fixes: 62eaf0ae217d ("drm/i915/guc: Support request cancellation")
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> Cc: <stable@vger.kernel.org>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Daniele
> ---
> .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 41 ++++++++++++++++---
> 1 file changed, 35 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> index d94e7e1a876f..592b421e1429 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -831,17 +831,33 @@ __unwind_incomplete_requests(struct intel_context *ce)
> static void __guc_reset_context(struct intel_context *ce, bool stalled)
> {
> struct i915_request *rq;
> + unsigned long flags;
> u32 head;
> + bool skip = false;
>
> intel_context_get(ce);
>
> /*
> - * GuC will implicitly mark the context as non-schedulable
> - * when it sends the reset notification. Make sure our state
> - * reflects this change. The context will be marked enabled
> - * on resubmission.
> + * GuC will implicitly mark the context as non-schedulable when it sends
> + * the reset notification. Make sure our state reflects this change. The
> + * context will be marked enabled on resubmission.
> + *
> + * XXX: If the context is reset as a result of the request cancellation
> + * this G2H is received after the schedule disable complete G2H which is
> + * wrong as this creates a race between the request cancellation code
> + * re-submitting the context and this G2H handler. This is a bug in the
> + * GuC but can be worked around in the meantime but converting this to a
> + * NOP if a pending enable is in flight as this indicates that a request
> + * cancellation has occurred.
> */
> - clr_context_enabled(ce);
> + spin_lock_irqsave(&ce->guc_state.lock, flags);
> + if (likely(!context_pending_enable(ce)))
> + clr_context_enabled(ce);
> + else
> + skip = true;
> + spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> + if (unlikely(skip))
> + goto out_put;
>
> rq = intel_context_find_active_request(ce);
> if (!rq) {
> @@ -860,6 +876,7 @@ static void __guc_reset_context(struct intel_context *ce, bool stalled)
> out_replay:
> guc_reset_state(ce, head, stalled);
> __unwind_incomplete_requests(ce);
> +out_put:
> intel_context_put(ce);
> }
>
> @@ -1604,6 +1621,13 @@ static void guc_context_cancel_request(struct intel_context *ce,
> guc_reset_state(ce, intel_ring_wrap(ce->ring, rq->head),
> true);
> }
> +
> + /*
> + * XXX: Racey if context is reset, see comment in
> + * __guc_reset_context().
> + */
> + flush_work(&ce_to_guc(ce)->ct.requests.worker);
> +
> guc_context_unblock(ce);
> }
> }
> @@ -2718,7 +2742,12 @@ static void guc_handle_context_reset(struct intel_guc *guc,
> {
> trace_intel_context_reset(ce);
>
> - if (likely(!intel_context_is_banned(ce))) {
> + /*
> + * XXX: Racey if request cancellation has occurred, see comment in
> + * __guc_reset_context().
> + */
> + if (likely(!intel_context_is_banned(ce) &&
> + !context_blocked(ce))) {
> capture_error_state(guc, ce);
> guc_context_replay(ce);
> }
next prev parent reply other threads:[~2021-08-26 23:11 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-26 3:23 [PATCH 00/27] Clean up GuC CI failures, simplify locking, and kernel DOC Matthew Brost
2021-08-26 3:23 ` [PATCH 01/27] drm/i915/guc: Fix blocked context accounting Matthew Brost
2021-08-26 3:23 ` [PATCH 02/27] drm/i915/guc: Fix outstanding G2H accounting Matthew Brost
2021-08-26 23:09 ` Daniele Ceraolo Spurio
2021-08-27 1:36 ` Matthew Brost
2021-08-26 3:23 ` [PATCH 03/27] drm/i915/guc: Unwind context requests in reverse order Matthew Brost
2021-08-26 3:23 ` [PATCH 04/27] drm/i915/guc: Don't drop ce->guc_active.lock when unwinding context Matthew Brost
2021-08-26 3:23 ` [PATCH 05/27] drm/i915/guc: Process all G2H message at once in work queue Matthew Brost
2021-08-26 3:23 ` [PATCH 06/27] drm/i915/guc: Workaround reset G2H is received after schedule done G2H Matthew Brost
2021-08-26 23:11 ` Daniele Ceraolo Spurio [this message]
2021-08-26 3:23 ` [PATCH 07/27] Revert "drm/i915/gt: Propagate change in error status to children on unhold" Matthew Brost
2021-08-26 3:23 ` [PATCH 08/27] drm/i915/selftests: Add a cancel request selftest that triggers a reset Matthew Brost
2021-08-26 9:32 ` [Intel-gfx] " Tvrtko Ursulin
2021-08-26 14:00 ` Matthew Brost
2021-08-26 3:23 ` [PATCH 09/27] drm/i915/guc: Kick tasklet after queuing a request Matthew Brost
2021-08-26 3:23 ` [PATCH 10/27] drm/i915/guc: Don't enable scheduling on a banned context, guc_id invalid, not registered Matthew Brost
2021-08-26 3:23 ` [PATCH 11/27] drm/i915/guc: Copy whole golden context, set engine state size of subset Matthew Brost
2021-08-26 23:21 ` Daniele Ceraolo Spurio
2021-08-26 23:33 ` [Intel-gfx] " John Harrison
2021-08-26 3:23 ` [PATCH 12/27] drm/i915/selftests: Add initial GuC selftest for scrubbing lost G2H Matthew Brost
2021-08-26 3:23 ` [PATCH 13/27] drm/i915/guc: Take context ref when cancelling request Matthew Brost
2021-08-26 3:23 ` [PATCH 14/27] drm/i915/guc: Don't touch guc_state.sched_state without a lock Matthew Brost
2021-08-26 3:23 ` [PATCH 15/27] drm/i915/guc: Reset LRC descriptor if register returns -ENODEV Matthew Brost
2021-08-26 3:23 ` [PATCH 16/27] drm/i915: Allocate error capture in nowait context Matthew Brost
2021-08-26 16:18 ` [Intel-gfx] " Matthew Brost
2021-08-26 16:21 ` Daniel Vetter
2021-08-26 3:23 ` [PATCH 17/27] drm/i915/guc: Flush G2H work queue during reset Matthew Brost
2021-08-26 3:23 ` [PATCH 18/27] drm/i915/guc: Release submit fence from an irq_work Matthew Brost
2021-08-26 3:23 ` [PATCH 19/27] drm/i915/guc: Move guc_blocked fence to struct guc_state Matthew Brost
2021-08-26 3:23 ` [PATCH 20/27] drm/i915/guc: Rework and simplify locking Matthew Brost
2021-08-26 3:23 ` [PATCH 21/27] drm/i915/guc: Proper xarray usage for contexts_lookup Matthew Brost
2021-08-26 3:23 ` [PATCH 22/27] drm/i915/guc: Drop pin count check trick between sched_disable and re-pin Matthew Brost
2021-08-26 3:23 ` [PATCH 23/27] drm/i915/guc: Move GuC priority fields in context under guc_active Matthew Brost
2021-08-26 23:26 ` Daniele Ceraolo Spurio
2021-08-26 3:23 ` [PATCH 24/27] drm/i915/guc: Move fields protected by guc->contexts_lock into sub structure Matthew Brost
2021-08-26 3:23 ` [PATCH 25/27] drm/i915/guc: Drop guc_active move everything into guc_state Matthew Brost
2021-08-26 3:23 ` [PATCH 26/27] drm/i915/guc: Add GuC kernel doc Matthew Brost
2021-08-31 19:04 ` [Intel-gfx] " John Harrison
2021-08-26 3:23 ` [PATCH 27/27] drm/i915/guc: Drop static inline functions intel_guc_submission.c Matthew Brost
2021-08-31 19:09 ` [Intel-gfx] " John Harrison
-- strict thread matches above, loose matches on Subject: below --
2021-08-19 6:16 [PATCH 00/27] Clean up GuC CI failures, simplify locking, and kernel DOC Matthew Brost
2021-08-19 6:16 ` [PATCH 06/27] drm/i915/guc: Workaround reset G2H is received after schedule done G2H Matthew Brost
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