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Message-ID: <fb9f1a22-fa68-9e7a-9159-90b87fbb27aa@intel.com>
Date:   Thu, 14 Jul 2022 16:06:28 +0200
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Subject: Re: [PATCH v2 09/21] drm/i915/guc: Define CTB based TLB invalidation
 routines
Content-Language: en-US
To:     Mauro Carvalho Chehab <mchehab@kernel.org>
Cc:     Prathap Kumar Valsan <prathap.kumar.valsan@intel.com>,
        Alan Previn <alan.previn.teres.alexis@intel.com>,
        Borislav Petkov <bp@suse.de>, Daniel Vetter <daniel@ffwll.ch>,
        Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>,
        David Airlie <airlied@linux.ie>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        John Harrison <John.C.Harrison@Intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Lucas De Marchi <lucas.demarchi@intel.com>,
        Matt Roper <matthew.d.roper@intel.com>,
        Matthew Brost <matthew.brost@intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>,
        Vinay Belgaumkar <vinay.belgaumkar@intel.com>,
        dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org,
        linux-kernel@vger.kernel.org,
        Bruce Chang <yu.bruce.chang@intel.com>,
        Chris Wilson <chris.p.wilson@intel.com>
References: <cover.1657800199.git.mchehab@kernel.org>
 <1be3eb5a7110012de506b3df01339b314c6643b7.1657800199.git.mchehab@kernel.org>
From:   Michal Wajdeczko <michal.wajdeczko@intel.com>
In-Reply-To: <1be3eb5a7110012de506b3df01339b314c6643b7.1657800199.git.mchehab@kernel.org>
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Precedence: bulk


On 14.07.2022 14:06, Mauro Carvalho Chehab wrote:
> From: Prathap Kumar Valsan <prathap.kumar.valsan@intel.com>
> 
> Add routines to interface with GuC firmware for TLB invalidation.
> 
> Signed-off-by: Prathap Kumar Valsan <prathap.kumar.valsan@intel.com>
> Cc: Bruce Chang <yu.bruce.chang@intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Chris Wilson <chris.p.wilson@intel.com>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> ---
> 
> To avoid mailbombing on a large number of people, only mailing lists were C/C on the cover.
> See [PATCH v2 00/21] at: https://lore.kernel.org/all/cover.1657800199.git.mchehab@kernel.org/
> 
>  .../gpu/drm/i915/gt/uc/abi/guc_actions_abi.h  | 35 +++++++
>  drivers/gpu/drm/i915/gt/uc/intel_guc.c        | 90 ++++++++++++++++++
>  drivers/gpu/drm/i915/gt/uc/intel_guc.h        | 13 +++
>  drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c     | 24 ++++-
>  drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h   |  6 ++
>  .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 91 ++++++++++++++++++-
>  6 files changed, 253 insertions(+), 6 deletions(-)
> 
> 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 4ef9990ed7f8..2e39d8df4c82 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
> @@ -134,6 +134,10 @@ 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_NOTIFY_MEMORY_CAT_ERROR = 0x6000,

should this be part of this patch ?

> +	INTEL_GUC_ACTION_PAGE_FAULT_NOTIFICATION = 0x6001,
> +	INTEL_GUC_ACTION_TLB_INVALIDATION = 0x7000,
> +	INTEL_GUC_ACTION_TLB_INVALIDATION_DONE = 0x7001,

can we document layout of these actions ?

>  	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,
> @@ -177,4 +181,35 @@ enum intel_guc_state_capture_event_status {
>  
>  #define INTEL_GUC_STATE_CAPTURE_EVENT_STATUS_MASK      0x000000FF
>  
> +#define INTEL_GUC_TLB_INVAL_TYPE_SHIFT 0
> +#define INTEL_GUC_TLB_INVAL_MODE_SHIFT 8

can we stop using SHIFT-based definitions and start using MASK-based
instead ? then we will be able to use FIELD_PREP/GET like we do for i915_reg

> +/* Flush PPC or SMRO caches along with TLB invalidation request */
> +#define INTEL_GUC_TLB_INVAL_FLUSH_CACHE (1 << 31)
> +
> +enum intel_guc_tlb_invalidation_type {
> +	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.
> + */

either drop this comment or squash with patch 10/21 to fix it

> +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.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> index 2706a8c65090..5c59f9b144a3 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> @@ -855,6 +855,96 @@ int intel_guc_self_cfg64(struct intel_guc *guc, u16 key, u64 value)
>  	return __guc_self_cfg(guc, key, 2, value);
>  }
>  
> +static int guc_send_invalidate_tlb(struct intel_guc *guc, u32 *action, u32 size)

nit: maybe since MMIO TLB has moved to dedicated file, we can do the
same with GUC TLB code like "intel_guc_tlb.c" ?

> +{
> +	struct intel_guc_tlb_wait _wq, *wq = &_wq;
> +	DEFINE_WAIT_FUNC(wait, woken_wake_function);
> +	int err = 0;
> +	u32 seqno;
> +
> +	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->status),
> +				    guc->tlb_lookup.xa_lock);
> +		/*
> +		 * Update wq->status 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 false before releasing the lock
> +		 * so that other caller continue to wait until woken up again.
> +		 */
> +		wq->status = 1;
> +		xa_unlock_irq(&guc->tlb_lookup);
> +
> +		seqno = guc->serial_slot;
> +	}
> +
> +	action[1] = seqno;

it's sad that we need to update in blind this action message

if you don't want to expose seqno allocation in a helper function that
each caller would use, then maybe assert that this action message is
expected one


> +
> +	add_wait_queue(&wq->wq, &wait);
> +
> +	err = intel_guc_send_busy_loop(guc, action, size, G2H_LEN_DW_INVALIDATE_TLB, true);
> +	if (err) {
> +		/*
> +		 * XXX: Failure of tlb invalidation is critical and would

s/tlb/TLB

> +		 * warrant a gt reset.
> +		 */
> +		goto out;
> +	}
> +/*
> + * GuC has a timeout of 1ms for a tlb invalidation response from GAM. On a

ditto

> + * timeout GuC drops the request and has no mechanism to notify the host about
> + * the timeout. So keep a larger timeout that accounts for this individual
> + * timeout and max number of outstanding invalidation requests that can be
> + * queued in CT buffer.
> + */
> +#define OUTSTANDING_GUC_TIMEOUT_PERIOD  (HZ)
> +	if (!wait_woken(&wait, TASK_UNINTERRUPTIBLE,

IIRC there was some discussion if we can rely on this in our scenario
can you sync with Chris on that?

> +			OUTSTANDING_GUC_TIMEOUT_PERIOD)) {
> +		/*
> +		 * XXX: Failure of tlb invalidation is critical and would

s/tlb/TLB

> +		 * warrant a gt reset.
> +		 */
> +		drm_err(&guc_to_gt(guc)->i915->drm,
> +			 "tlb invalidation response timed out for seqno %u\n", seqno);

s/tlb/TLB

btw, should we care here about G2H_LEN_DW_INVALIDATE_TLB space that we
reserved in send_busy_loop() ?

> +		err = -ETIME;
> +	}
> +out:
> +	remove_wait_queue(&wq->wq, &wait);
> +	if (seqno != guc->serial_slot)
> +		xa_erase_irq(&guc->tlb_lookup, seqno);
> +
> +	return err;
> +}
> +
> +/*
> + * Guc TLB Invalidation: Invalidate the TLB's of GuC itself.
> + */
> +int intel_guc_invalidate_tlb_guc(struct intel_guc *guc,
> +				 enum intel_guc_tlb_inval_mode mode)
> +{
> +	u32 action[] = {
> +		INTEL_GUC_ACTION_TLB_INVALIDATION,
> +		0,
> +		INTEL_GUC_TLB_INVAL_GUC << INTEL_GUC_TLB_INVAL_TYPE_SHIFT |
> +			mode << INTEL_GUC_TLB_INVAL_MODE_SHIFT |
> +			INTEL_GUC_TLB_INVAL_FLUSH_CACHE,
> +	};
> +
> +	if (!INTEL_GUC_SUPPORTS_TLB_INVALIDATION(guc)) {
> +		DRM_ERROR("Tlb invalidation: Operation not supported in this platform!\n");

you should use drm_err() instead

but wondering if maybe this should be treated as a coding error (and
then use GEM_BUG/WARN_ON instead) but then not sure how to interpret the
check for the intel_guc_ct_enabled() embedded in above macro ...
note that intel_guc_ct_send() will return -ENODEV if CTB is down

> +		return 0;
> +	}
> +
> +	return guc_send_invalidate_tlb(guc, action, ARRAY_SIZE(action));
> +}
> +
>  /**
>   * intel_guc_load_status - dump information about GuC load status
>   * @guc: the GuC
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> index d0d99f178f2d..f82a121b0838 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> @@ -77,6 +77,10 @@ struct intel_guc {
>  	atomic_t outstanding_submission_g2h;
>  
>  	/** @interrupts: pointers to GuC interrupt-managing functions. */
> +	struct xarray tlb_lookup;
> +	u32 serial_slot;
> +	u32 next_seqno;

wrong place - above kernel-doc is for the struct below

> +
>  	struct {
>  		void (*reset)(struct intel_guc *guc);
>  		void (*enable)(struct intel_guc *guc);
> @@ -248,6 +252,11 @@ struct intel_guc {
>  #endif
>  };
>  
> +struct intel_guc_tlb_wait {
> +	struct wait_queue_head wq;
> +	u8 status;
> +} __aligned(4);
> +
>  static inline struct intel_guc *log_to_guc(struct intel_guc_log *log)
>  {
>  	return container_of(log, struct intel_guc, log);
> @@ -363,6 +372,9 @@ int intel_guc_allocate_and_map_vma(struct intel_guc *guc, u32 size,
>  int intel_guc_self_cfg32(struct intel_guc *guc, u16 key, u32 value);
>  int intel_guc_self_cfg64(struct intel_guc *guc, u16 key, u64 value);
>  
> +int intel_guc_invalidate_tlb_guc(struct intel_guc *guc,
> +				 enum intel_guc_tlb_inval_mode mode);
> +
>  static inline bool intel_guc_is_supported(struct intel_guc *guc)
>  {
>  	return intel_uc_fw_is_supported(&guc->fw);
> @@ -440,6 +452,7 @@ int intel_guc_engine_failure_process_msg(struct intel_guc *guc,
>  					 const u32 *msg, u32 len);
>  int intel_guc_error_capture_process_msg(struct intel_guc *guc,
>  					const u32 *msg, u32 len);
> +void intel_guc_tlb_invalidation_done(struct intel_guc *guc, u32 seqno);
>  
>  struct intel_engine_cs *
>  intel_guc_lookup_engine(struct intel_guc *guc, u8 guc_class, u8 instance);
> 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 f01325cd1b62..c1ce542b7855 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> @@ -1023,7 +1023,7 @@ static int ct_process_request(struct intel_guc_ct *ct, struct ct_incoming_msg *r
>  	return 0;
>  }
>  
> -static bool ct_process_incoming_requests(struct intel_guc_ct *ct)
> +static bool ct_process_incoming_requests(struct intel_guc_ct *ct, struct list_head *incoming)
>  {
>  	unsigned long flags;
>  	struct ct_incoming_msg *request;
> @@ -1031,11 +1031,11 @@ static bool ct_process_incoming_requests(struct intel_guc_ct *ct)
>  	int err;
>  
>  	spin_lock_irqsave(&ct->requests.lock, flags);
> -	request = list_first_entry_or_null(&ct->requests.incoming,
> +	request = list_first_entry_or_null(incoming,
>  					   struct ct_incoming_msg, link);
>  	if (request)
>  		list_del(&request->link);
> -	done = !!list_empty(&ct->requests.incoming);
> +	done = !!list_empty(incoming);
>  	spin_unlock_irqrestore(&ct->requests.lock, flags);
>  
>  	if (!request)
> @@ -1058,7 +1058,7 @@ static void ct_incoming_request_worker_func(struct work_struct *w)
>  	bool done;
>  
>  	do {
> -		done = ct_process_incoming_requests(ct);
> +		done = ct_process_incoming_requests(ct, &ct->requests.incoming);
>  	} while (!done);
>  }
>  
> @@ -1078,14 +1078,30 @@ 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);
>  	}
> +	/* Handle tlb invalidation response in interrupt context */

since it breaks layering, can you add more comments why this is done in
such way ?

> +	if (action == INTEL_GUC_ACTION_TLB_INVALIDATION_DONE) {
> +		const u32 *payload;
> +		u32 hxg_len, len;
> +
> +		hxg_len = request->size - GUC_CTB_MSG_MIN_LEN;
> +		len = hxg_len - GUC_HXG_MSG_MIN_LEN;
> +		if (unlikely(len < 1))
> +			return -EPROTO;
> +		payload = &hxg[GUC_HXG_MSG_MIN_LEN];

if we still need to handle this at this level, can we at least move this
message decomposition to the handler (in other words: just pass hxg
pointer instead of single dword payload)

> +		intel_guc_tlb_invalidation_done(ct_to_guc(ct),  payload[0]);
> +		ct_free_msg(request);
> +		return 0;
> +	}
>  
>  	spin_lock_irqsave(&ct->requests.lock, flags);
>  	list_add_tail(&request->link, &ct->requests.incoming);
>  	spin_unlock_irqrestore(&ct->requests.lock, flags);
>  
>  	queue_work(system_unbound_wq, &ct->requests.worker);
> +
>  	return 0;
>  }
>  
> 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 b3c9a9327f76..3edf567b3f65 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
> @@ -431,4 +432,9 @@ enum intel_guc_recv_message {
>  	INTEL_GUC_RECV_MSG_EXCEPTION = BIT(30),
>  };
>  
> +#define INTEL_GUC_SUPPORTS_TLB_INVALIDATION(guc) \
> +	((intel_guc_ct_enabled(&(guc)->ct)) && \

do we need this check ?
CTB is prerequisite for submission that is required below

> +	 (intel_guc_submission_is_used(guc)) && \
> +	 (GRAPHICS_VER(guc_to_gt((guc))->i915) >= 12))
> +
>  #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 40f726c61e95..6888ea1bc7c1 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -1653,11 +1653,20 @@ static void __guc_reset_context(struct intel_context *ce, intel_engine_mask_t st
>  	intel_context_put(parent);
>  }
>  
> +static void wake_up_tlb_invalidate(struct intel_guc_tlb_wait *wait)
> +{
> +	/* Barrier to ensure the store is observed by the woken thread */
> +	smp_store_mb(wait->status, 0);
> +	wake_up(&wait->wq);
> +}
> +
>  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! */
> @@ -1683,6 +1692,13 @@ 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.
> +	 */
> +	xa_for_each(&guc->tlb_lookup, i, wait)
> +		wake_up_tlb_invalidate(wait);

shouldn't this be closer to intel_guc_invalidate_tlb_guc()
then we can avoid spreading code across many files

same for the init/fini_tlb_lookup() functions below

>  }
>  
>  static void guc_cancel_context_requests(struct intel_context *ce)
> @@ -1805,6 +1821,41 @@ 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);
>  
> +static int init_tlb_lookup(struct intel_guc *guc)
> +{
> +	struct intel_guc_tlb_wait *wait;
> +	int err;
> +
> +	xa_init_flags(&guc->tlb_lookup, XA_FLAGS_ALLOC);
> +
> +	wait = kzalloc(sizeof(*wait), GFP_KERNEL);
> +	if (!wait)
> +		return -ENOMEM;
> +
> +	init_waitqueue_head(&wait->wq);
> +	err = xa_alloc_cyclic_irq(&guc->tlb_lookup, &guc->serial_slot, wait,
> +				  xa_limit_32b, &guc->next_seqno, GFP_KERNEL);
> +	if (err == -ENOMEM) {
> +		kfree(wait);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static void fini_tlb_lookup(struct intel_guc *guc)
> +{
> +	struct intel_guc_tlb_wait *wait;
> +
> +	wait = xa_load(&guc->tlb_lookup, guc->serial_slot);
> +	if (wait) {
> +		GEM_BUG_ON(wait->status);
> +		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.
> @@ -1812,20 +1863,31 @@ static void reset_fail_worker_func(struct work_struct *w);
>  int intel_guc_submission_init(struct intel_guc *guc)
>  {
>  	struct intel_gt *gt = guc_to_gt(guc);
> +	int ret;
>  
>  	if (guc->submission_initialized)
>  		return 0;
>  
> +	ret = init_tlb_lookup(guc);

if we promote guc_tlb to own file/functions then maybe it could be
init/fini directly from __uc_init_hw() ?

> +	if (ret)
> +		return ret;
> +
>  	guc->submission_state.guc_ids_bitmap =
>  		bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID(guc), GFP_KERNEL);
> -	if (!guc->submission_state.guc_ids_bitmap)
> -		return -ENOMEM;
> +	if (!guc->submission_state.guc_ids_bitmap) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
>  
>  	guc->timestamp.ping_delay = (POLL_TIME_CLKS / gt->clock_frequency + 1) * HZ;
>  	guc->timestamp.shift = gpm_timestamp_shift(gt);
>  	guc->submission_initialized = true;
>  
>  	return 0;
> +
> +err:
> +	fini_tlb_lookup(guc);
> +	return ret;
>  }
>  
>  void intel_guc_submission_fini(struct intel_guc *guc)
> @@ -1836,6 +1898,7 @@ void intel_guc_submission_fini(struct intel_guc *guc)
>  	guc_flush_destroyed_contexts(guc);
>  	i915_sched_engine_put(guc->sched_engine);
>  	bitmap_free(guc->submission_state.guc_ids_bitmap);
> +	fini_tlb_lookup(guc);
>  	guc->submission_initialized = false;
>  }
>  
> @@ -4027,6 +4090,30 @@ 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);
> +
> +	/* We received a response after the waiting task did exit with a timeout */
> +	if (unlikely(!wait))
> +		drm_dbg(&guc_to_gt(guc)->i915->drm,
> +			"Stale tlb invalidation response with seqno %d\n", seqno);

hmm, this sounds like a problem as we shouldn't get any late
notifications - do we really want to hide it under drm_dbg ?

> +
> +	if (wait)
> +		wake_up_tlb_invalidate(wait);
> +
> +	xa_unlock_irqrestore(&guc->tlb_lookup, flags);
> +}
> +
> +void intel_guc_tlb_invalidation_done(struct intel_guc *guc, u32 seqno)
> +{
> +	wait_wake_outstanding_tlb_g2h(guc, seqno);
> +}
> +
>  int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
>  					  const u32 *msg,
>  					  u32 len)

,Michal