Re: [Intel-gfx] [PATCH v4 12/17] drm/i915/pxp: start the arb session on demand

[Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>]

On 6/2/2021 11:14 AM, Rodrigo Vivi wrote:
> On Mon, May 24, 2021 at 10:47:58PM -0700, Daniele Ceraolo Spurio wrote:
>> Now that we can handle destruction and re-creation of the arb session,
>> we can postpone the start of the session to the first submission that
>> requires it, to avoid keeping it running with no user.
>>
>> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>> ---
>>   .../gpu/drm/i915/gem/i915_gem_execbuffer.c    |  8 ++--
>>   drivers/gpu/drm/i915/pxp/intel_pxp.c          | 37 ++++++++++++-------
>>   drivers/gpu/drm/i915/pxp/intel_pxp.h          |  4 +-
>>   drivers/gpu/drm/i915/pxp/intel_pxp_irq.c      |  2 +-
>>   drivers/gpu/drm/i915/pxp/intel_pxp_session.c  |  6 +--
>>   drivers/gpu/drm/i915/pxp/intel_pxp_tee.c      | 10 +----
>>   drivers/gpu/drm/i915/pxp/intel_pxp_types.h    |  3 ++
>>   7 files changed, 39 insertions(+), 31 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
>> index a11e9d5767bf..c08e28847064 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
>> @@ -2948,9 +2948,11 @@ eb_select_engine(struct i915_execbuffer *eb)
>>   	intel_gt_pm_get(ce->engine->gt);
>>   
>>   	if (i915_gem_context_uses_protected_content(eb->gem_context)) {
>> -		err = intel_pxp_wait_for_arb_start(&ce->engine->gt->pxp);
>> -		if (err)
>> -			goto err;
>> +		if (!intel_pxp_is_active(&ce->engine->gt->pxp)) {
>> +			err = intel_pxp_start(&ce->engine->gt->pxp);
>> +			if (err)
>> +				goto err;
>> +		}
>>   
>>   		if (i915_gem_context_invalidated(eb->gem_context)) {
>>   			err = -EACCES;
>> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp.c b/drivers/gpu/drm/i915/pxp/intel_pxp.c
>> index f713d3423cea..2291c68fd3a0 100644
>> --- a/drivers/gpu/drm/i915/pxp/intel_pxp.c
>> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp.c
>> @@ -77,6 +77,7 @@ void intel_pxp_init(struct intel_pxp *pxp)
>>   	init_completion(&pxp->termination);
>>   	complete_all(&pxp->termination);
>>   
>> +	mutex_init(&pxp->arb_mutex);
>>   	INIT_WORK(&pxp->session_work, intel_pxp_session_work);
>>   
>>   	ret = create_vcs_context(pxp);
>> @@ -113,7 +114,7 @@ void intel_pxp_mark_termination_in_progress(struct intel_pxp *pxp)
>>   	reinit_completion(&pxp->termination);
>>   }
>>   
>> -static void intel_pxp_queue_termination(struct intel_pxp *pxp)
>> +static void pxp_queue_termination(struct intel_pxp *pxp)
>>   {
>>   	struct intel_gt *gt = pxp_to_gt(pxp);
>>   
>> @@ -132,31 +133,41 @@ static void intel_pxp_queue_termination(struct intel_pxp *pxp)
>>    * the arb session is restarted from the irq work when we receive the
>>    * termination completion interrupt
>>    */
>> -int intel_pxp_wait_for_arb_start(struct intel_pxp *pxp)
>> +int intel_pxp_start(struct intel_pxp *pxp)
>>   {
>> +	int ret = 0;
>> +
>>   	if (!intel_pxp_is_enabled(pxp))
>> -		return 0;
>> +		return -ENODEV;
>> +
>> +	mutex_lock(&pxp->arb_mutex);
>> +
>> +	if (pxp->arb_is_valid)
>> +		goto unlock;
>> +
>> +	pxp_queue_termination(pxp);
>>   
>>   	if (!wait_for_completion_timeout(&pxp->termination,
>> -					 msecs_to_jiffies(100)))
>> -		return -ETIMEDOUT;
>> +					msecs_to_jiffies(100))) {
>> +		ret = -ETIMEDOUT;
>> +		goto unlock;
>> +	}
>> +
>> +	/* make sure the compiler doesn't optimize the double access */
>> +	barrier();
>>   
>>   	if (!pxp->arb_is_valid)
>> -		return -EIO;
>> +		ret = -EIO;
>>   
>> -	return 0;
>> +unlock:
>> +	mutex_unlock(&pxp->arb_mutex);
>> +	return ret;
>>   }
>>   
>>   void intel_pxp_init_hw(struct intel_pxp *pxp)
>>   {
>>   	kcr_pxp_enable(pxp_to_gt(pxp));
>>   	intel_pxp_irq_enable(pxp);
>> -
>> -	/*
>> -	 * the session could've been attacked while we weren't loaded, so
>> -	 * handle it as if it was and re-create it.
>> -	 */
>> -	intel_pxp_queue_termination(pxp);
>>   }
>>   
>>   void intel_pxp_fini_hw(struct intel_pxp *pxp)
>> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp.h b/drivers/gpu/drm/i915/pxp/intel_pxp.h
>> index 91c1a2056309..1f9871e64096 100644
>> --- a/drivers/gpu/drm/i915/pxp/intel_pxp.h
>> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp.h
>> @@ -32,7 +32,7 @@ void intel_pxp_init_hw(struct intel_pxp *pxp);
>>   void intel_pxp_fini_hw(struct intel_pxp *pxp);
>>   
>>   void intel_pxp_mark_termination_in_progress(struct intel_pxp *pxp);
>> -int intel_pxp_wait_for_arb_start(struct intel_pxp *pxp);
>> +int intel_pxp_start(struct intel_pxp *pxp);
>>   void intel_pxp_invalidate(struct intel_pxp *pxp);
>>   #else
>>   static inline void intel_pxp_init(struct intel_pxp *pxp)
>> @@ -43,7 +43,7 @@ static inline void intel_pxp_fini(struct intel_pxp *pxp)
>>   {
>>   }
>>   
>> -static inline int intel_pxp_wait_for_arb_start(struct intel_pxp *pxp)
>> +static inline int intel_pxp_start(struct intel_pxp *pxp)
>>   {
>>   	return 0;
>>   }
>> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_irq.c b/drivers/gpu/drm/i915/pxp/intel_pxp_irq.c
>> index 196449243515..a230d0034e50 100644
>> --- a/drivers/gpu/drm/i915/pxp/intel_pxp_irq.c
>> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_irq.c
>> @@ -31,7 +31,7 @@ void intel_pxp_irq_handler(struct intel_pxp *pxp, u16 iir)
>>   		   GEN12_DISPLAY_APP_TERMINATED_PER_FW_REQ_INTERRUPT)) {
>>   		/* immediately mark PXP as inactive on termination */
>>   		intel_pxp_mark_termination_in_progress(pxp);
>> -		pxp->session_events |= PXP_TERMINATION_REQUEST;
>> +		pxp->session_events |= PXP_TERMINATION_REQUEST | PXP_INVAL_REQUIRED;
>>   	}
>>   
>>   	if (iir & GEN12_DISPLAY_STATE_RESET_COMPLETE_INTERRUPT)
>> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_session.c b/drivers/gpu/drm/i915/pxp/intel_pxp_session.c
>> index e9fe757e368a..c21620916710 100644
>> --- a/drivers/gpu/drm/i915/pxp/intel_pxp_session.c
>> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_session.c
>> @@ -85,9 +85,6 @@ static int pxp_terminate_arb_session_and_global(struct intel_pxp *pxp)
>>   	/* must mark termination in progress calling this function */
>>   	GEM_WARN_ON(pxp->arb_is_valid);
>>   
>> -	/* invalidate protected objects */
>> -	intel_pxp_invalidate(pxp);
>> -
>>   	/* terminate the hw sessions */
>>   	ret = intel_pxp_terminate_session(pxp, ARB_SESSION);
>>   	if (ret) {
>> @@ -144,6 +141,9 @@ void intel_pxp_session_work(struct work_struct *work)
>>   	if (!events)
>>   		return;
>>   
>> +	if (events & PXP_INVAL_REQUIRED)
>> +		intel_pxp_invalidate(pxp);
>> +
> doesn't this invalidation change deserves a separated patch?
> I'm not sure if I understood why we need this change...

Before this patch, we always did a full invalidation and an arb restart 
back-to-back and therefore the invalidation was implicit in the 
PXP_TERMINATION_REQUEST flag. This patch changes this into different cases:

termination irq: invalidate objects, submit termination and restart the 
arb session
suspend: invalidate objects
first pxp submission: submit termination and start the arb session

Therefore we need to be able to select the invalidation as an 
independent case from the termination.

Daniele


>
>>   	if (events & PXP_TERMINATION_REQUEST) {
>>   		events &= ~PXP_TERMINATION_COMPLETE;
>>   		pxp_terminate(pxp);
>> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_tee.c b/drivers/gpu/drm/i915/pxp/intel_pxp_tee.c
>> index e3d178c44e51..35b3fed4ca2f 100644
>> --- a/drivers/gpu/drm/i915/pxp/intel_pxp_tee.c
>> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_tee.c
>> @@ -63,23 +63,15 @@ static int intel_pxp_tee_io_message(struct intel_pxp *pxp,
>>   static int i915_pxp_tee_component_bind(struct device *i915_kdev,
>>   				       struct device *tee_kdev, void *data)
>>   {
>> -	struct drm_i915_private *i915 = kdev_to_i915(i915_kdev);
>>   	struct intel_pxp *pxp = i915_dev_to_pxp(i915_kdev);
>> -	int ret;
>>   
>>   	pxp->pxp_component = data;
>>   	pxp->pxp_component->tee_dev = tee_kdev;
>>   
>>   	/* the component is required to fully start the PXP HW */
>>   	intel_pxp_init_hw(pxp);
>> -	ret = intel_pxp_wait_for_arb_start(pxp);
>> -	if (ret) {
>> -		drm_err(&i915->drm, "Failed to create arb session during bind\n");
>> -		intel_pxp_fini_hw(pxp);
>> -		pxp->pxp_component = NULL;
>> -	}
>>   
>> -	return ret;
>> +	return 0;
>>   }
>>   
>>   static void i915_pxp_tee_component_unbind(struct device *i915_kdev,
>> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_types.h b/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
>> index c059a17cbcfe..b3ae49dd73a8 100644
>> --- a/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
>> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_types.h
>> @@ -7,6 +7,7 @@
>>   #define __INTEL_PXP_TYPES_H__
>>   
>>   #include <linux/completion.h>
>> +#include <linux/mutex.h>
>>   #include <linux/types.h>
>>   #include <linux/workqueue.h>
>>   
>> @@ -23,6 +24,7 @@ struct intel_pxp {
>>   	 * even if the keys are gone, so we can't rely on the HW state of the
>>   	 * session to know if it's valid and need to track the status in SW.
>>   	 */
>> +	struct mutex arb_mutex; /* protects arb session start */
>>   	bool arb_is_valid;
>>   
>>   	/*
>> @@ -40,6 +42,7 @@ struct intel_pxp {
>>   	u32 session_events; /* protected with gt->irq_lock */
>>   #define PXP_TERMINATION_REQUEST  BIT(0)
>>   #define PXP_TERMINATION_COMPLETE BIT(1)
>> +#define PXP_INVAL_REQUIRED       BIT(2)
>>   };
>>   
>>   #endif /* __INTEL_PXP_TYPES_H__ */
>> -- 
>> 2.29.2
>>
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