[Intel-gfx] [PATCH 01/26] drm/i915/guc: Move GuC guc_id allocation under submission state sub-struct

John Harrison john.c.harrison at intel.com
Thu Oct 7 18:13:14 UTC 2021


On 10/7/2021 08:05, Matthew Brost wrote:
> On Wed, Oct 06, 2021 at 08:06:41PM -0700, John Harrison wrote:
>> On 10/4/2021 15:06, Matthew Brost wrote:
>>> Move guc_id allocation under submission state sub-struct as a future
>>> patch will reuse the spin lock as a global submission state lock. Moving
>>> this into sub-struct makes ownership of fields / lock clear.
>>>
>>> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
>>> ---
>>>    drivers/gpu/drm/i915/gt/intel_context_types.h |  6 +-
>>>    drivers/gpu/drm/i915/gt/uc/intel_guc.h        | 26 +++++----
>>>    .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 56 ++++++++++---------
>>>    3 files changed, 47 insertions(+), 41 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
>>> index 12252c411159..e7e3984aab78 100644
>>> --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
>>> +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
>>> @@ -197,18 +197,18 @@ struct intel_context {
>>>    	struct {
>>>    		/**
>>>    		 * @id: handle which is used to uniquely identify this context
>>> -		 * with the GuC, protected by guc->contexts_lock
>>> +		 * with the GuC, protected by guc->submission_state.lock
>>>    		 */
>>>    		u16 id;
>>>    		/**
>>>    		 * @ref: the number of references to the guc_id, when
>>>    		 * transitioning in and out of zero protected by
>>> -		 * guc->contexts_lock
>>> +		 * guc->submission_state.lock
>>>    		 */
>>>    		atomic_t ref;
>>>    		/**
>>>    		 * @link: in guc->guc_id_list when the guc_id has no refs but is
>>> -		 * still valid, protected by guc->contexts_lock
>>> +		 * still valid, protected by guc->submission_state.lock
>>>    		 */
>>>    		struct list_head link;
>>>    	} guc_id;
>>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
>>> index 5dd174babf7a..65b5e8eeef96 100644
>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
>>> @@ -70,17 +70,21 @@ struct intel_guc {
>>>    		void (*disable)(struct intel_guc *guc);
>>>    	} interrupts;
>>> -	/**
>>> -	 * @contexts_lock: protects guc_ids, guc_id_list, ce->guc_id.id, and
>>> -	 * ce->guc_id.ref when transitioning in and out of zero
>>> -	 */
>>> -	spinlock_t contexts_lock;
>>> -	/** @guc_ids: used to allocate unique ce->guc_id.id values */
>>> -	struct ida guc_ids;
>>> -	/**
>>> -	 * @guc_id_list: list of intel_context with valid guc_ids but no refs
>>> -	 */
>>> -	struct list_head guc_id_list;
>>> +	struct {
>>> +		/**
>>> +		 * @lock: protects everything in submission_state
>>> +		 */
>>> +		spinlock_t lock;
>> The old version also mentioned 'ce->guc_id.ref'. Should this not also
>> mention that transition? Or was the old comment inaccurate. I'm not seeing
>> any actual behaviour changes in the patch.
>>
>>
> Can add that back in.
>
>>> +		/**
>>> +		 * @guc_ids: used to allocate new guc_ids
>>> +		 */
>>> +		struct ida guc_ids;
>>> +		/**
>>> +		 * @guc_id_list: list of intel_context with valid guc_ids but no
>>> +		 * refs
>>> +		 */
>>> +		struct list_head guc_id_list;
>>> +	} submission_state;
>>>    	/**
>>>    	 * @submission_supported: tracks whether we support GuC submission on
>>> 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 ba0de35f6323..ad5c18119d92 100644
>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
>>> @@ -68,16 +68,16 @@
>>>     * fence is used to stall all requests associated with this guc_id until the
>>>     * corresponding G2H returns indicating the guc_id has been deregistered.
>>>     *
>>> - * guc_ids:
>>> + * submission_state.guc_ids:
>>>     * Unique number associated with private GuC context data passed in during
>>>     * context registration / submission / deregistration. 64k available. Simple ida
>>>     * is used for allocation.
>>>     *
>>> - * Stealing guc_ids:
>>> - * If no guc_ids are available they can be stolen from another context at
>>> - * request creation time if that context is unpinned. If a guc_id can't be found
>>> - * we punt this problem to the user as we believe this is near impossible to hit
>>> - * during normal use cases.
>>> + * Stealing submission_state.guc_ids:
>>> + * If no submission_state.guc_ids are available they can be stolen from another
>> I would abbreviate this instance as well, submission_state.guc_id is quite
>> the mouthful. Unless this somehow magically links back to the structure
>> entry in the kerneldoc output?
>>
> It might, not really sure but agree the submission_state should be
> dropped. Think changed because of global find replace.
>
> Matt
Okay. With those nits fixed:
Reviewed by: John Harrison <John.C.Harrison at Intel.com>

>> John.
>>
>>> + * context at request creation time if that context is unpinned. If a guc_id
>>> + * can't be found we punt this problem to the user as we believe this is near
>>> + * impossible to hit during normal use cases.
>>>     *
>>>     * Locking:
>>>     * In the GuC submission code we have 3 basic spin locks which protect
>>> @@ -89,7 +89,7 @@
>>>     * sched_engine can be submitting at a time. Currently only one sched_engine is
>>>     * used for all of GuC submission but that could change in the future.
>>>     *
>>> - * guc->contexts_lock
>>> + * guc->submission_state.lock
>>>     * Protects guc_id allocation for the given GuC, i.e. only one context can be
>>>     * doing guc_id allocation operations at a time for each GuC in the system.
>>>     *
>>> @@ -103,7 +103,7 @@
>>>     *
>>>     * Lock ordering rules:
>>>     * sched_engine->lock -> ce->guc_state.lock
>>> - * guc->contexts_lock -> ce->guc_state.lock
>>> + * guc->submission_state.lock -> ce->guc_state.lock
>>>     *
>>>     * Reset races:
>>>     * When a full GT reset is triggered it is assumed that some G2H responses to
>>> @@ -1148,9 +1148,9 @@ int intel_guc_submission_init(struct intel_guc *guc)
>>>    	xa_init_flags(&guc->context_lookup, XA_FLAGS_LOCK_IRQ);
>>> -	spin_lock_init(&guc->contexts_lock);
>>> -	INIT_LIST_HEAD(&guc->guc_id_list);
>>> -	ida_init(&guc->guc_ids);
>>> +	spin_lock_init(&guc->submission_state.lock);
>>> +	INIT_LIST_HEAD(&guc->submission_state.guc_id_list);
>>> +	ida_init(&guc->submission_state.guc_ids);
>>>    	return 0;
>>>    }
>>> @@ -1215,7 +1215,7 @@ static void guc_submit_request(struct i915_request *rq)
>>>    static int new_guc_id(struct intel_guc *guc)
>>>    {
>>> -	return ida_simple_get(&guc->guc_ids, 0,
>>> +	return ida_simple_get(&guc->submission_state.guc_ids, 0,
>>>    			      GUC_MAX_LRC_DESCRIPTORS, GFP_KERNEL |
>>>    			      __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
>>>    }
>>> @@ -1223,7 +1223,8 @@ static int new_guc_id(struct intel_guc *guc)
>>>    static void __release_guc_id(struct intel_guc *guc, struct intel_context *ce)
>>>    {
>>>    	if (!context_guc_id_invalid(ce)) {
>>> -		ida_simple_remove(&guc->guc_ids, ce->guc_id.id);
>>> +		ida_simple_remove(&guc->submission_state.guc_ids,
>>> +				  ce->guc_id.id);
>>>    		reset_lrc_desc(guc, ce->guc_id.id);
>>>    		set_context_guc_id_invalid(ce);
>>>    	}
>>> @@ -1235,9 +1236,9 @@ static void release_guc_id(struct intel_guc *guc, struct intel_context *ce)
>>>    {
>>>    	unsigned long flags;
>>> -	spin_lock_irqsave(&guc->contexts_lock, flags);
>>> +	spin_lock_irqsave(&guc->submission_state.lock, flags);
>>>    	__release_guc_id(guc, ce);
>>> -	spin_unlock_irqrestore(&guc->contexts_lock, flags);
>>> +	spin_unlock_irqrestore(&guc->submission_state.lock, flags);
>>>    }
>>>    static int steal_guc_id(struct intel_guc *guc)
>>> @@ -1245,10 +1246,10 @@ static int steal_guc_id(struct intel_guc *guc)
>>>    	struct intel_context *ce;
>>>    	int guc_id;
>>> -	lockdep_assert_held(&guc->contexts_lock);
>>> +	lockdep_assert_held(&guc->submission_state.lock);
>>> -	if (!list_empty(&guc->guc_id_list)) {
>>> -		ce = list_first_entry(&guc->guc_id_list,
>>> +	if (!list_empty(&guc->submission_state.guc_id_list)) {
>>> +		ce = list_first_entry(&guc->submission_state.guc_id_list,
>>>    				      struct intel_context,
>>>    				      guc_id.link);
>>> @@ -1273,7 +1274,7 @@ static int assign_guc_id(struct intel_guc *guc, u16 *out)
>>>    {
>>>    	int ret;
>>> -	lockdep_assert_held(&guc->contexts_lock);
>>> +	lockdep_assert_held(&guc->submission_state.lock);
>>>    	ret = new_guc_id(guc);
>>>    	if (unlikely(ret < 0)) {
>>> @@ -1295,7 +1296,7 @@ static int pin_guc_id(struct intel_guc *guc, struct intel_context *ce)
>>>    	GEM_BUG_ON(atomic_read(&ce->guc_id.ref));
>>>    try_again:
>>> -	spin_lock_irqsave(&guc->contexts_lock, flags);
>>> +	spin_lock_irqsave(&guc->submission_state.lock, flags);
>>>    	might_lock(&ce->guc_state.lock);
>>> @@ -1310,7 +1311,7 @@ static int pin_guc_id(struct intel_guc *guc, struct intel_context *ce)
>>>    	atomic_inc(&ce->guc_id.ref);
>>>    out_unlock:
>>> -	spin_unlock_irqrestore(&guc->contexts_lock, flags);
>>> +	spin_unlock_irqrestore(&guc->submission_state.lock, flags);
>>>    	/*
>>>    	 * -EAGAIN indicates no guc_id are available, let's retire any
>>> @@ -1346,11 +1347,12 @@ static void unpin_guc_id(struct intel_guc *guc, struct intel_context *ce)
>>>    	if (unlikely(context_guc_id_invalid(ce)))
>>>    		return;
>>> -	spin_lock_irqsave(&guc->contexts_lock, flags);
>>> +	spin_lock_irqsave(&guc->submission_state.lock, flags);
>>>    	if (!context_guc_id_invalid(ce) && list_empty(&ce->guc_id.link) &&
>>>    	    !atomic_read(&ce->guc_id.ref))
>>> -		list_add_tail(&ce->guc_id.link, &guc->guc_id_list);
>>> -	spin_unlock_irqrestore(&guc->contexts_lock, flags);
>>> +		list_add_tail(&ce->guc_id.link,
>>> +			      &guc->submission_state.guc_id_list);
>>> +	spin_unlock_irqrestore(&guc->submission_state.lock, flags);
>>>    }
>>>    static int __guc_action_register_context(struct intel_guc *guc,
>>> @@ -1921,16 +1923,16 @@ static void guc_context_destroy(struct kref *kref)
>>>    	 * returns indicating this context has been deregistered the guc_id is
>>>    	 * returned to the pool of available guc_id.
>>>    	 */
>>> -	spin_lock_irqsave(&guc->contexts_lock, flags);
>>> +	spin_lock_irqsave(&guc->submission_state.lock, flags);
>>>    	if (context_guc_id_invalid(ce)) {
>>> -		spin_unlock_irqrestore(&guc->contexts_lock, flags);
>>> +		spin_unlock_irqrestore(&guc->submission_state.lock, flags);
>>>    		__guc_context_destroy(ce);
>>>    		return;
>>>    	}
>>>    	if (!list_empty(&ce->guc_id.link))
>>>    		list_del_init(&ce->guc_id.link);
>>> -	spin_unlock_irqrestore(&guc->contexts_lock, flags);
>>> +	spin_unlock_irqrestore(&guc->submission_state.lock, flags);
>>>    	/* Seal race with Reset */
>>>    	spin_lock_irqsave(&ce->guc_state.lock, flags);



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