Re: [PATCH v4 3/3] drm/i915: No TLB invalidation on wedged or suspended GT

[Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>]

On 03/10/2023 22:01, Jonathan Cavitt wrote:
> In case of GT is suspended or wedged, don't allow submission of new TLB
> invalidation request and cancel all pending requests. The TLB entries
> will be invalidated either during GuC reload or on system resume.
>
> Signed-off-by: Fei Yang <fei.yang@xxxxxxxxx>
> Signed-off-by: Jonathan Cavitt <jonathan.cavitt@xxxxxxxxx>
> CC: John Harrison <john.c.harrison@xxxxxxxxx>
> ---
>   drivers/gpu/drm/i915/gt/intel_gt.h            | 26 ++++++++++++
>   drivers/gpu/drm/i915/gt/uc/intel_guc.h        |  1 +
>   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 41 +++++++++++++++----
>   drivers/gpu/drm/i915/i915_driver.c            |  5 +++
>   4 files changed, 64 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt.h b/drivers/gpu/drm/i915/gt/intel_gt.h
> index 970bedf6b78a7..71a0e376ded40 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gt.h
> @@ -9,6 +9,7 @@
>   #include "intel_engine_types.h"
>   #include "intel_gt_types.h"
>   #include "intel_reset.h"
> +#include "i915_drv.h"
>   
>   struct drm_i915_private;
>   struct drm_printer;
> @@ -179,4 +180,29 @@ enum i915_map_type intel_gt_coherent_map_type(struct intel_gt *gt,
>   void intel_gt_bind_context_set_ready(struct intel_gt *gt);
>   void intel_gt_bind_context_set_unready(struct intel_gt *gt);
>   bool intel_gt_is_bind_context_ready(struct intel_gt *gt);
> +
> +static inline void intel_tlb_suspend(struct drm_i915_private *i915)
> +{
> +	struct intel_gt *gt;
> +	int i;
> +
> +	if (!HAS_GUC_TLB_INVALIDATION(i915))
> +		return;
> +	for_each_gt(gt, i915, i)
> +		wake_up_all_tlb_invalidate(&gt->uc.guc);
> +}
> +
> +static inline void intel_tlb_resume(struct drm_i915_private *i915)
> +{
> +	struct intel_gt *gt;
> +	int i;
> +
> +	if (!HAS_GUC_TLB_INVALIDATION(i915))
> +		return;
> +	for_each_gt(gt, i915, i) {
> +		intel_guc_invalidate_tlb_full(&gt->uc.guc);
> +		intel_guc_invalidate_tlb(&gt->uc.guc);

Why full and not full? At least the naming suggestes first to be 
superset of the second.

> +	}
> +}

I see no justification for static inlines and I see no reason not to 
have this in intel_tlb.h|c.

Also, I suggested having them called from intel_gt_suspend(_*) and 
intel_gt_resume. Or there is also intel_uc_suspend/resume. Either of 
those places would benefit from the existing for_each_gt applied at the 
GEM level, when it calls into the GT component.

Are those at the wrong spot in the suspend/resume sequence so it 
wouldn't work?

Maybe it is a matter of taste but since the implementation is so GT 
centric (everything added operates strictly on a &gt->uc.guc pointer) 
that it really looks to me it should be better placed in one of those 
two components.

Regards,

Tvrtko

> +
>   #endif /* __INTEL_GT_H__ */
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> index 636edf598946c..e2491f489f1bc 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> @@ -536,4 +536,5 @@ void intel_guc_dump_time_info(struct intel_guc *guc, struct drm_printer *p);
>   
>   int intel_guc_sched_disable_gucid_threshold_max(struct intel_guc *guc);
>   
> +void wake_up_all_tlb_invalidate(struct intel_guc *guc);
>   #endif
> 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 872014a801c7e..20e9076cf099e 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -32,6 +32,7 @@
>   
>   #include "i915_drv.h"
>   #include "i915_reg.h"
> +#include "i915_irq.h"
>   #include "i915_trace.h"
>   
>   /**
> @@ -1796,13 +1797,23 @@ static void __guc_reset_context(struct intel_context *ce, intel_engine_mask_t st
>   	intel_context_put(parent);
>   }
>   
> -void intel_guc_submission_reset(struct intel_guc *guc, intel_engine_mask_t stalled)
> +void wake_up_all_tlb_invalidate(struct intel_guc *guc)
>   {
>   	struct intel_guc_tlb_wait *wait;
> +	unsigned long i;
> +
> +	xa_for_each(&guc->tlb_lookup, i, wait) {
> +		/* Barrier to ensure the store is observed by the woken thread */
> +		smp_store_mb(wait->busy, 0);
> +		wake_up(&wait->wq);
> +	}
> +}
> +
> +void intel_guc_submission_reset(struct intel_guc *guc, intel_engine_mask_t stalled)
> +{
>   	struct intel_context *ce;
>   	unsigned long index;
>   	unsigned long flags;
> -	unsigned long i;
>   
>   	if (unlikely(!guc_submission_initialized(guc))) {
>   		/* Reset called during driver load? GuC not yet initialised! */
> @@ -1833,11 +1844,7 @@ void intel_guc_submission_reset(struct intel_guc *guc, intel_engine_mask_t stall
>   	 * The full GT reset will have cleared the TLB caches and flushed the
>   	 * G2H message queue; we can release all the blocked waiters.
>   	 */
> -	xa_for_each(&guc->tlb_lookup, i, wait) {
> -		/* Barrier to ensure the store is observed by the woken thread */
> -		smp_store_mb(wait->busy, 0);
> -		wake_up(&wait->wq);
> -	}
> +	wake_up_all_tlb_invalidate(guc);
>   }
>   
>   static void guc_cancel_context_requests(struct intel_context *ce)
> @@ -1933,6 +1940,12 @@ void intel_guc_submission_cancel_requests(struct intel_guc *guc)
>   
>   	/* GuC is blown away, drop all references to contexts */
>   	xa_destroy(&guc->context_lookup);
> +
> +	/*
> +	 * Wedged GT won't respond to any TLB invalidation request. Simply
> +	 * release all the blocked waiters.
> +	 */
> +	wake_up_all_tlb_invalidate(guc);
>   }
>   
>   void intel_guc_submission_reset_finish(struct intel_guc *guc)
> @@ -4740,6 +4753,14 @@ static long must_wait_woken(struct wait_queue_entry *wq_entry, long timeout)
>   	return timeout;
>   }
>   
> +static bool intel_gt_is_enabled(const struct intel_gt *gt)
> +{
> +	/* Check if GT is wedged or suspended */
> +	if (intel_gt_is_wedged(gt) || !intel_irqs_enabled(gt->i915))
> +		return false;
> +	return true;
> +}
> +
>   static int guc_send_invalidate_tlb(struct intel_guc *guc, u32 type)
>   {
>   	struct intel_guc_tlb_wait _wq, *wq = &_wq;
> @@ -4757,7 +4778,8 @@ static int guc_send_invalidate_tlb(struct intel_guc *guc, u32 type)
>   	};
>   	u32 size = ARRAY_SIZE(action);
>   
> -	if (!intel_guc_ct_enabled(&guc->ct))
> +	if (!intel_gt_is_enabled(gt) ||
> +	    !intel_guc_ct_enabled(&guc->ct))
>   		return -EINVAL;
>   
>   	init_waitqueue_head(&_wq.wq);
> @@ -4800,7 +4822,8 @@ static int guc_send_invalidate_tlb(struct intel_guc *guc, u32 type)
>   	 * requests that can be queued in CT buffer.
>   	 */
>   #define OUTSTANDING_GUC_TIMEOUT_PERIOD  (HZ * 2)
> -	if (!must_wait_woken(&wait, OUTSTANDING_GUC_TIMEOUT_PERIOD)) {
> +	if (intel_gt_is_enabled(gt) &&
> +	    !must_wait_woken(&wait, OUTSTANDING_GUC_TIMEOUT_PERIOD)) {
>   		gt_err(gt,
>   		       "TLB invalidation response timed out for seqno %u\n", seqno);
>   		err = -ETIME;
> diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
> index 78501a83ba109..66bd765d00302 100644
> --- a/drivers/gpu/drm/i915/i915_driver.c
> +++ b/drivers/gpu/drm/i915/i915_driver.c
> @@ -1092,6 +1092,9 @@ static int i915_drm_suspend(struct drm_device *dev)
>   	intel_dp_mst_suspend(dev_priv);
>   
>   	intel_runtime_pm_disable_interrupts(dev_priv);
> +
> +	intel_tlb_suspend(dev_priv);
> +
>   	intel_hpd_cancel_work(dev_priv);
>   
>   	intel_suspend_encoders(dev_priv);
> @@ -1263,6 +1266,8 @@ static int i915_drm_resume(struct drm_device *dev)
>   
>   	intel_gvt_resume(dev_priv);
>   
> +	intel_tlb_resume(dev_priv);
> +
>   	enable_rpm_wakeref_asserts(&dev_priv->runtime_pm);
>   
>   	return 0;