[Intel-gfx] [PATCH v13 3/7] drm/i915: Define and use GuC and CTB TLB invalidation routines

Cavitt, Jonathan jonathan.cavitt at intel.com
Fri Oct 13 14:52:07 UTC 2023


-----Original Message-----
From: Harrison, John C <john.c.harrison at intel.com> 
Sent: Thursday, October 12, 2023 6:11 PM
To: Cavitt, Jonathan <jonathan.cavitt at intel.com>; intel-gfx at lists.freedesktop.org
Cc: Gupta, saurabhg <saurabhg.gupta at intel.com>; chris.p.wilson at linux.intel.com; Iddamsetty, Aravind <aravind.iddamsetty at intel.com>; Yang, Fei <fei.yang at intel.com>; Shyti, Andi <andi.shyti at intel.com>; Das, Nirmoy <nirmoy.das at intel.com>; Krzysztofik, Janusz <janusz.krzysztofik at intel.com>; Roper, Matthew D <matthew.d.roper at intel.com>; tvrtko.ursulin at linux.intel.com; jani.nikula at linux.intel.com
Subject: Re: [PATCH v13 3/7] drm/i915: Define and use GuC and CTB TLB invalidation routines
> 
> On 10/12/2023 15:38, Jonathan Cavitt wrote:
> > From: Prathap Kumar Valsan <prathap.kumar.valsan at intel.com>
> >
> > The GuC firmware had defined the interface for Translation Look-Aside
> > Buffer (TLB) invalidation.  We should use this interface when
> > invalidating the engine and GuC TLBs.
> > Add additional functionality to intel_gt_invalidate_tlb, invalidating
> > the GuC TLBs and falling back to GT invalidation when the GuC is
> > disabled.
> > The invalidation is done by sending a request directly to the GuC
> > tlb_lookup that invalidates the table.  The invalidation is submitted as
> > a wait request and is performed in the CT event handler.  This means we
> > cannot perform this TLB invalidation path if the CT is not enabled.
> > If the request isn't fulfilled in two seconds, this would constitute
> > an error in the invalidation as that would constitute either a lost
> > request or a severe GuC overload.
> >
> > With this new invalidation routine, we can perform GuC-based GGTT
> > invalidations.  GuC-based GGTT invalidation is incompatible with
> > MMIO invalidation so we should not perform MMIO invalidation when
> > GuC-based GGTT invalidation is expected.
> >
> > The additional complexity incurred in this patch will be necessary for
> > range-based tlb invalidations, which will be platformed in the future.
> >
> > Signed-off-by: Prathap Kumar Valsan <prathap.kumar.valsan at intel.com>
> > Signed-off-by: Bruce Chang <yu.bruce.chang at intel.com>
> > Signed-off-by: Chris Wilson <chris.p.wilson at intel.com>
> > Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
> > Signed-off-by: Jonathan Cavitt <jonathan.cavitt at intel.com>
> > Signed-off-by: Aravind Iddamsetty <aravind.iddamsetty at intel.com>
> > Signed-off-by: Fei Yang <fei.yang at intel.com>
> > CC: Andi Shyti <andi.shyti at linux.intel.com>
> > Reviewed-by: Andi Shyti <andi.shyti at linux.intel.com>
> > Acked-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > Acked-by: Nirmoy Das <nirmoy.das at intel.com>
> > Reviewed-by: John Harrison <John.C.Harrison at Intel.com>
> > ---
> >   drivers/gpu/drm/i915/gt/intel_ggtt.c          |  33 ++-
> >   drivers/gpu/drm/i915/gt/intel_tlb.c           |  16 +-
> >   .../gpu/drm/i915/gt/uc/abi/guc_actions_abi.h  |  33 +++
> >   drivers/gpu/drm/i915/gt/uc/intel_guc.h        |  22 ++
> >   drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c     |  11 +
> >   drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h   |   1 +
> >   .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 195 +++++++++++++++++-
> >   7 files changed, 299 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
> > index 4d7d88b92632b..7d145b2d3cb17 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
> > @@ -206,22 +206,37 @@ static void gen8_ggtt_invalidate(struct i915_ggtt *ggtt)
> >   	intel_uncore_write_fw(uncore, GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
> >   }
> >   
> > +static void guc_ggtt_ct_invalidate(struct intel_gt *gt)
> > +{
> > +	struct intel_uncore *uncore = gt->uncore;
> > +	intel_wakeref_t wakeref;
> > +
> > +	with_intel_runtime_pm_if_active(uncore->rpm, wakeref) {
> > +		struct intel_guc *guc = &gt->uc.guc;
> > +
> > +		intel_guc_invalidate_tlb_guc(guc);
> > +	}
> > +}
> > +
> >   static void guc_ggtt_invalidate(struct i915_ggtt *ggtt)
> >   {
> >   	struct drm_i915_private *i915 = ggtt->vm.i915;
> > +	struct intel_gt *gt;
> >   
> > -	gen8_ggtt_invalidate(ggtt);
> > -
> > -	if (GRAPHICS_VER(i915) >= 12) {
> > -		struct intel_gt *gt;
> > +	if (!HAS_GUC_TLB_INVALIDATION(i915))
> > +		gen8_ggtt_invalidate(ggtt);
> This has not changed? As per comments from Matthew Roper and Nirmoy Das, 
> there needs to be a fixup patch first to stop gen8_ggtt_invalidate() 
> from being called on invalid platforms.


Given the sounds of things, it seems like this change here is irrelevant to this patch series, as the reason we're
guarding against gen8_ggtt_invalidate isn't related to GuC-based TLB invalidations at all.  Ergo, it would actually
make more sense for me to not skip it here and leave the respective guard change to a different patch series.
-Jonathan Cavitt


> 
> >   
> > -		list_for_each_entry(gt, &ggtt->gt_list, ggtt_link)
> > +	list_for_each_entry(gt, &ggtt->gt_list, ggtt_link) {
> > +		if (intel_guc_tlb_invalidation_is_available(&gt->uc.guc)) {
> > +			guc_ggtt_ct_invalidate(gt);
> > +		} else if (GRAPHICS_VER(i915) >= 12) {
> >   			intel_uncore_write_fw(gt->uncore,
> >   					      GEN12_GUC_TLB_INV_CR,
> >   					      GEN12_GUC_TLB_INV_CR_INVALIDATE);
> > -	} else {
> > -		intel_uncore_write_fw(ggtt->vm.gt->uncore,
> > -				      GEN8_GTCR, GEN8_GTCR_INVALIDATE);
> > +		} else {
> > +			intel_uncore_write_fw(gt->uncore,
> > +					      GEN8_GTCR, GEN8_GTCR_INVALIDATE);
> > +		}
> >   	}
> >   }
> >   
> > @@ -1243,7 +1258,7 @@ static int gen8_gmch_probe(struct i915_ggtt *ggtt)
> >   		ggtt->vm.raw_insert_page = gen8_ggtt_insert_page;
> >   	}
> >   
> > -	if (intel_uc_wants_guc(&ggtt->vm.gt->uc))
> > +	if (intel_uc_wants_guc_submission(&ggtt->vm.gt->uc))
> >   		ggtt->invalidate = guc_ggtt_invalidate;
> >   	else
> >   		ggtt->invalidate = gen8_ggtt_invalidate;
> > diff --git a/drivers/gpu/drm/i915/gt/intel_tlb.c b/drivers/gpu/drm/i915/gt/intel_tlb.c
> > index 139608c30d978..4bb13d1890e37 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_tlb.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_tlb.c
> > @@ -12,6 +12,7 @@
> >   #include "intel_gt_print.h"
> >   #include "intel_gt_regs.h"
> >   #include "intel_tlb.h"
> > +#include "uc/intel_guc.h"
> >   
> >   /*
> >    * HW architecture suggest typical invalidation time at 40us,
> > @@ -131,11 +132,24 @@ void intel_gt_invalidate_tlb_full(struct intel_gt *gt, u32 seqno)
> >   		return;
> >   
> >   	with_intel_gt_pm_if_awake(gt, wakeref) {
> > +		struct intel_guc *guc = &gt->uc.guc;
> > +
> >   		mutex_lock(&gt->tlb.invalidate_lock);
> >   		if (tlb_seqno_passed(gt, seqno))
> >   			goto unlock;
> >   
> > -		mmio_invalidate_full(gt);
> > +		if (HAS_GUC_TLB_INVALIDATION(gt->i915)) {
> > +			/*
> > +			 * Only perform GuC TLB invalidation if GuC is ready.
> > +			 * The only time GuC could not be ready is on GT reset,
> > +			 * which would clobber all the TLBs anyways, making
> > +			 * any TLB invalidation path here unnecessary.
> > +			 */
> > +			if (intel_guc_is_ready(guc))
> > +				intel_guc_invalidate_tlb_engines(guc);
> > +		} else {
> > +			mmio_invalidate_full(gt);
> > +		}
> >   
> >   		write_seqcount_invalidate(&gt->tlb.seqno);
> >   unlock:
> > diff --git a/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h b/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h
> > index f359bef046e0b..33f253410d0c8 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h
> > +++ b/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h
> > @@ -138,6 +138,8 @@ enum intel_guc_action {
> >   	INTEL_GUC_ACTION_REGISTER_CONTEXT_MULTI_LRC = 0x4601,
> >   	INTEL_GUC_ACTION_CLIENT_SOFT_RESET = 0x5507,
> >   	INTEL_GUC_ACTION_SET_ENG_UTIL_BUFF = 0x550A,
> > +	INTEL_GUC_ACTION_TLB_INVALIDATION = 0x7000,
> > +	INTEL_GUC_ACTION_TLB_INVALIDATION_DONE = 0x7001,
> >   	INTEL_GUC_ACTION_STATE_CAPTURE_NOTIFICATION = 0x8002,
> >   	INTEL_GUC_ACTION_NOTIFY_FLUSH_LOG_BUFFER_TO_FILE = 0x8003,
> >   	INTEL_GUC_ACTION_NOTIFY_CRASH_DUMP_POSTED = 0x8004,
> > @@ -181,4 +183,35 @@ enum intel_guc_state_capture_event_status {
> >   
> >   #define INTEL_GUC_STATE_CAPTURE_EVENT_STATUS_MASK      0x000000FF
> >   
> > +#define INTEL_GUC_TLB_INVAL_TYPE_MASK	REG_GENMASK(7, 0)
> > +#define INTEL_GUC_TLB_INVAL_MODE_MASK	REG_GENMASK(11, 8)
> > +#define INTEL_GUC_TLB_INVAL_FLUSH_CACHE REG_BIT(31)
> > +
> > +enum intel_guc_tlb_invalidation_type {
> > +	INTEL_GUC_TLB_INVAL_ENGINES = 0x0,
> > +	INTEL_GUC_TLB_INVAL_GUC = 0x3,
> > +};
> > +
> > +/*
> > + * 0: Heavy mode of Invalidation:
> > + * The pipeline of the engine(s) for which the invalidation is targeted to is
> > + * blocked, and all the in-flight transactions are guaranteed to be Globally
> > + * Observed before completing the TLB invalidation
> > + * 1: Lite mode of Invalidation:
> > + * TLBs of the targeted engine(s) are immediately invalidated.
> > + * In-flight transactions are NOT guaranteed to be Globally Observed before
> > + * completing TLB invalidation.
> > + * Light Invalidation Mode is to be used only when
> > + * it can be guaranteed (by SW) that the address translations remain invariant
> > + * for the in-flight transactions across the TLB invalidation. In other words,
> > + * this mode can be used when the TLB invalidation is intended to clear out the
> > + * stale cached translations that are no longer in use. Light Invalidation Mode
> > + * is much faster than the Heavy Invalidation Mode, as it does not wait for the
> > + * in-flight transactions to be GOd.
> > + */
> > +enum intel_guc_tlb_inval_mode {
> > +	INTEL_GUC_TLB_INVAL_MODE_HEAVY = 0x0,
> > +	INTEL_GUC_TLB_INVAL_MODE_LITE = 0x1,
> > +};
> > +
> >   #endif /* _ABI_GUC_ACTIONS_ABI_H */
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > index 818c8c146fd47..0949628d69f8b 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > @@ -79,6 +79,18 @@ struct intel_guc {
> >   	 */
> >   	atomic_t outstanding_submission_g2h;
> >   
> > +	/** @tlb_lookup: xarray to store all pending TLB invalidation requests */
> > +	struct xarray tlb_lookup;
> > +
> > +	/**
> > +	 * @serial_slot: id to the initial waiter created in tlb_lookup,
> > +	 * which is used only when failed to allocate new waiter.
> > +	 */
> > +	u32 serial_slot;
> > +
> > +	/** @next_seqno: the next id (sequence number) to allocate. */
> > +	u32 next_seqno;
> > +
> >   	/** @interrupts: pointers to GuC interrupt-managing functions. */
> >   	struct {
> >   		bool enabled;
> > @@ -288,6 +300,11 @@ struct intel_guc {
> >   #endif
> >   };
> >   
> > +struct intel_guc_tlb_wait {
> > +	struct wait_queue_head wq;
> > +	bool busy;
> > +};
> > +
> >   /*
> >    * GuC version number components are only 8-bit, so converting to a 32bit 8.8.8
> >    * integer works.
> > @@ -515,4 +532,9 @@ 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);
> >   
> > +bool intel_guc_tlb_invalidation_is_available(struct intel_guc *guc);
> > +int intel_guc_invalidate_tlb_engines(struct intel_guc *guc);
> > +int intel_guc_invalidate_tlb_guc(struct intel_guc *guc);
> > +int intel_guc_tlb_invalidation_done(struct intel_guc *guc,
> > +				    const u32 *payload, u32 len);
> >   #endif
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> > index 03b616ba4ebb7..89e314b3756bb 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> > @@ -1142,6 +1142,9 @@ static int ct_process_request(struct intel_guc_ct *ct, struct ct_incoming_msg *r
> >   	case INTEL_GUC_ACTION_NOTIFY_EXCEPTION:
> >   		ret = intel_guc_crash_process_msg(guc, action);
> >   		break;
> > +	case INTEL_GUC_ACTION_TLB_INVALIDATION_DONE:
> > +		ret = intel_guc_tlb_invalidation_done(guc, payload, len);
> > +		break;
> >   	default:
> >   		ret = -EOPNOTSUPP;
> >   		break;
> > @@ -1213,9 +1216,17 @@ static int ct_handle_event(struct intel_guc_ct *ct, struct ct_incoming_msg *requ
> >   	switch (action) {
> >   	case INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_DONE:
> >   	case INTEL_GUC_ACTION_DEREGISTER_CONTEXT_DONE:
> > +	case INTEL_GUC_ACTION_TLB_INVALIDATION_DONE:
> >   		g2h_release_space(ct, request->size);
> >   	}
> >   
> > +	/*
> > +	 * TLB invalidation responses must be handled immediately as processing
> > +	 * of other G2H notifications may be blocked by an invalidation request.
> > +	 */
> > +	if (action == INTEL_GUC_ACTION_TLB_INVALIDATION_DONE)
> > +		return ct_process_request(ct, request);
> > +
> >   	spin_lock_irqsave(&ct->requests.lock, flags);
> >   	list_add_tail(&request->link, &ct->requests.incoming);
> >   	spin_unlock_irqrestore(&ct->requests.lock, flags);
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h b/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h
> > index 123ad75d2eb28..8ae1846431da7 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h
> > @@ -22,6 +22,7 @@
> >   /* Payload length only i.e. don't include G2H header length */
> >   #define G2H_LEN_DW_SCHED_CONTEXT_MODE_SET	2
> >   #define G2H_LEN_DW_DEREGISTER_CONTEXT		1
> > +#define G2H_LEN_DW_INVALIDATE_TLB		1
> >   
> >   #define GUC_CONTEXT_DISABLE		0
> >   #define GUC_CONTEXT_ENABLE		1
> > 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 2cce5ec1ff00d..1377398afcdfa 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > @@ -1798,9 +1798,11 @@ static void __guc_reset_context(struct intel_context *ce, intel_engine_mask_t st
> >   
> >   void intel_guc_submission_reset(struct intel_guc *guc, intel_engine_mask_t stalled)
> >   {
> > +	struct intel_guc_tlb_wait *wait;
> >   	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! */
> > @@ -1826,6 +1828,17 @@ void intel_guc_submission_reset(struct intel_guc *guc, intel_engine_mask_t stall
> >   
> >   	/* GuC is blown away, drop all references to contexts */
> >   	xa_destroy(&guc->context_lookup);
> > +
> > +	/*
> > +	 * The full GT reset will have cleared the TLB caches and flushed the
> > +	 * G2H message queue; we can release all the blocked waiters.
> > +	 */
> > +	if (HAS_GUC_TLB_INVALIDATION(guc_to_gt(guc)->i915)) {
> > +		xa_lock_irq(&guc->tlb_lookup);
> > +		xa_for_each(&guc->tlb_lookup, i, wait)
> > +			wake_up(&wait->wq);
> > +		xa_unlock_irq(&guc->tlb_lookup);
> > +	}
> >   }
> >   
> >   static void guc_cancel_context_requests(struct intel_context *ce)
> > @@ -1948,6 +1961,54 @@ void intel_guc_submission_reset_finish(struct intel_guc *guc)
> >   static void destroyed_worker_func(struct work_struct *w);
> >   static void reset_fail_worker_func(struct work_struct *w);
> >   
> > +bool intel_guc_tlb_invalidation_is_available(struct intel_guc *guc)
> > +{
> > +	return HAS_GUC_TLB_INVALIDATION(guc_to_gt(guc)->i915) &&
> > +		intel_guc_is_ready(guc);
> > +}
> > +
> > +static int init_tlb_lookup(struct intel_guc *guc)
> > +{
> > +	struct intel_guc_tlb_wait *wait;
> > +	int err;
> > +
> > +	if (!HAS_GUC_TLB_INVALIDATION(guc_to_gt(guc)->i915))
> > +		return 0;
> > +
> > +	xa_init_flags(&guc->tlb_lookup, XA_FLAGS_ALLOC);
> > +
> > +	wait = kzalloc(sizeof(*wait), GFP_KERNEL);
> > +	if (!wait)
> > +		return -ENOMEM;
> > +
> > +	init_waitqueue_head(&wait->wq);
> > +
> > +	/* Preallocate a shared id for use under memory pressure. */
> > +	err = xa_alloc_cyclic_irq(&guc->tlb_lookup, &guc->serial_slot, wait,
> > +				  xa_limit_32b, &guc->next_seqno, GFP_KERNEL);
> > +	if (err < 0) {
> > +		kfree(wait);
> > +		return err;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static void fini_tlb_lookup(struct intel_guc *guc)
> > +{
> > +	struct intel_guc_tlb_wait *wait;
> > +
> > +	if (!HAS_GUC_TLB_INVALIDATION(guc_to_gt(guc)->i915))
> > +		return;
> > +
> > +	wait = xa_load(&guc->tlb_lookup, guc->serial_slot);
> > +	if (wait && wait->busy)
> > +		guc_err(guc, "Unexpected busy item in tlb_lookup on fini\n");
> > +	kfree(wait);
> > +
> > +	xa_destroy(&guc->tlb_lookup);
> > +}
> > +
> >   /*
> >    * Set up the memory resources to be shared with the GuC (via the GGTT)
> >    * at firmware loading time.
> > @@ -1966,11 +2027,15 @@ int intel_guc_submission_init(struct intel_guc *guc)
> >   			return ret;
> >   	}
> >   
> > +	ret = init_tlb_lookup(guc);
> > +	if (ret)
> > +		goto destroy_pool;
> > +
> >   	guc->submission_state.guc_ids_bitmap =
> >   		bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID(guc), GFP_KERNEL);
> >   	if (!guc->submission_state.guc_ids_bitmap) {
> >   		ret = -ENOMEM;
> > -		goto destroy_pool;
> > +		goto destroy_tlb;
> >   	}
> >   
> >   	guc->timestamp.ping_delay = (POLL_TIME_CLKS / gt->clock_frequency + 1) * HZ;
> > @@ -1979,9 +2044,10 @@ int intel_guc_submission_init(struct intel_guc *guc)
> >   
> >   	return 0;
> >   
> > +destroy_tlb:
> > +	fini_tlb_lookup(guc);
> >   destroy_pool:
> >   	guc_lrc_desc_pool_destroy_v69(guc);
> > -
> >   	return ret;
> >   }
> >   
> > @@ -1994,6 +2060,7 @@ void intel_guc_submission_fini(struct intel_guc *guc)
> >   	guc_lrc_desc_pool_destroy_v69(guc);
> >   	i915_sched_engine_put(guc->sched_engine);
> >   	bitmap_free(guc->submission_state.guc_ids_bitmap);
> > +	fini_tlb_lookup(guc);
> >   	guc->submission_initialized = false;
> >   }
> >   
> > @@ -4624,6 +4691,130 @@ g2h_context_lookup(struct intel_guc *guc, u32 ctx_id)
> >   	return ce;
> >   }
> >   
> > +static void wait_wake_outstanding_tlb_g2h(struct intel_guc *guc, u32 seqno)
> > +{
> > +	struct intel_guc_tlb_wait *wait;
> > +	unsigned long flags;
> > +
> > +	xa_lock_irqsave(&guc->tlb_lookup, flags);
> > +	wait = xa_load(&guc->tlb_lookup, seqno);
> > +
> > +	if (wait)
> > +		wake_up(&wait->wq);
> > +	else
> > +		guc_dbg(guc,
> > +			"Stale TLB invalidation response with seqno %d\n", seqno);
> > +
> > +	xa_unlock_irqrestore(&guc->tlb_lookup, flags);
> > +}
> > +
> > +int intel_guc_tlb_invalidation_done(struct intel_guc *guc,
> > +				    const u32 *payload, u32 len)
> > +{
> > +	if (len < 1)
> > +		return -EPROTO;
> Missing blank line.
> 
> John.
> 
> > +	wait_wake_outstanding_tlb_g2h(guc, payload[0]);
> > +	return 0;
> > +}
> > +
> > +static long must_wait_woken(struct wait_queue_entry *wq_entry, long timeout)
> > +{
> > +	/*
> > +	 * This is equivalent to wait_woken() with the exception that
> > +	 * we do not wake up early if the kthread task has been completed.
> > +	 * As we are called from page reclaim in any task context,
> > +	 * we may be invoked from stopped kthreads, but we *must*
> > +	 * complete the wait from the HW.
> > +	 */
> > +	do {
> > +		set_current_state(TASK_UNINTERRUPTIBLE);
> > +		if (wq_entry->flags & WQ_FLAG_WOKEN)
> > +			break;
> > +
> > +		timeout = schedule_timeout(timeout);
> > +	} while (timeout);
> > +
> > +	/* See wait_woken() and woken_wake_function() */
> > +	__set_current_state(TASK_RUNNING);
> > +	smp_store_mb(wq_entry->flags, wq_entry->flags & ~WQ_FLAG_WOKEN);
> > +
> > +	return timeout;
> > +}
> > +
> > +static int guc_send_invalidate_tlb(struct intel_guc *guc,
> > +				   enum intel_guc_tlb_invalidation_type type)
> > +{
> > +	struct intel_guc_tlb_wait _wq, *wq = &_wq;
> > +	DEFINE_WAIT_FUNC(wait, woken_wake_function);
> > +	int err;
> > +	u32 seqno;
> > +	u32 action[] = {
> > +		INTEL_GUC_ACTION_TLB_INVALIDATION,
> > +		0,
> > +		REG_FIELD_PREP(INTEL_GUC_TLB_INVAL_TYPE_MASK, type) |
> > +			REG_FIELD_PREP(INTEL_GUC_TLB_INVAL_MODE_MASK,
> > +				       INTEL_GUC_TLB_INVAL_MODE_HEAVY) |
> > +			INTEL_GUC_TLB_INVAL_FLUSH_CACHE,
> > +	};
> > +	u32 size = ARRAY_SIZE(action);
> > +
> > +	init_waitqueue_head(&_wq.wq);
> > +
> > +	if (xa_alloc_cyclic_irq(&guc->tlb_lookup, &seqno, wq,
> > +				xa_limit_32b, &guc->next_seqno,
> > +				GFP_ATOMIC | __GFP_NOWARN) < 0) {
> > +		/* Under severe memory pressure? Serialise TLB allocations */
> > +		xa_lock_irq(&guc->tlb_lookup);
> > +		wq = xa_load(&guc->tlb_lookup, guc->serial_slot);
> > +		wait_event_lock_irq(wq->wq,
> > +				    !READ_ONCE(wq->busy),
> > +				    guc->tlb_lookup.xa_lock);
> > +		/*
> > +		 * Update wq->busy under lock to ensure only one waiter can
> > +		 * issue the TLB invalidation command using the serial slot at a
> > +		 * time. The condition is set to true before releasing the lock
> > +		 * so that other caller continue to wait until woken up again.
> > +		 */
> > +		wq->busy = true;
> > +		xa_unlock_irq(&guc->tlb_lookup);
> > +
> > +		seqno = guc->serial_slot;
> > +	}
> > +
> > +	action[1] = seqno;
> > +
> > +	add_wait_queue(&wq->wq, &wait);
> > +
> > +	/* This is a critical reclaim path and thus we must loop here. */
> > +	err = intel_guc_send_busy_loop(guc, action, size, G2H_LEN_DW_INVALIDATE_TLB, true);
> > +	if (err)
> > +		goto out;
> > +
> > +	if (!must_wait_woken(&wait, intel_guc_ct_max_queue_time_jiffies())) {
> > +		guc_err(guc,
> > +			"TLB invalidation response timed out for seqno %u\n", seqno);
> > +		err = -ETIME;
> > +	}
> > +out:
> > +	remove_wait_queue(&wq->wq, &wait);
> > +	if (seqno != guc->serial_slot)
> > +		xa_erase_irq(&guc->tlb_lookup, seqno);
> > +
> > +	return err;
> > +}
> > +
> > +/* Send a H2G command to invalidate the TLBs at engine level and beyond. */
> > +int intel_guc_invalidate_tlb_engines(struct intel_guc *guc)
> > +{
> > +	return guc_send_invalidate_tlb(guc, INTEL_GUC_TLB_INVAL_ENGINES);
> > +}
> > +
> > +/* Send a H2G command to invalidate the GuC's internal TLB. */
> > +int intel_guc_invalidate_tlb_guc(struct intel_guc *guc)
> > +{
> > +	return guc_send_invalidate_tlb(guc, INTEL_GUC_TLB_INVAL_GUC);
> > +}
> > +
> >   int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
> >   					  const u32 *msg,
> >   					  u32 len)
> 
> 


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