RE: [PATCH v4 1/2] drm/xe/pagefault: Add SRCID to pagefault struct

[Cavitt, Jonathan]

-----Original Message-----
From: Brost, Matthew <matthew.brost@xxxxxxxxx> 
Sent: Monday, June 22, 2026 10:13 PM
To: Cavitt, Jonathan <jonathan.cavitt@xxxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx; Gupta, Saurabhg <saurabhg.gupta@xxxxxxxxx>; Zuo, Alex <alex.zuo@xxxxxxxxx>; mripard@xxxxxxxxxx; airlied@xxxxxxxxx; simona@xxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; intel-xe@xxxxxxxxxxxxxxxxxxxxx; Vivi, Rodrigo <rodrigo.vivi@xxxxxxxxx>; maarten.lankhorst@xxxxxxxxxxxxxxx; thomas.hellstrom@xxxxxxxxxxxxxxx; tzimmermann@xxxxxxx
Subject: Re: [PATCH v4 1/2] drm/xe/pagefault: Add SRCID to pagefault struct
> 
> On Thu, Jun 18, 2026 at 11:33:11PM +0800, Jonathan Cavitt wrote:
> > Add SRCID information to pagefault struct for the purpose of reporting
> > the hardware unit that resulted in the pagefault.
> > 
> > v2:
> > - Squash SRCID with ASID to keep the struct compact (Matthew)
> > 
> > Signed-off-by: Jonathan Cavitt <jonathan.cavitt@xxxxxxxxx>
> > Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
> > Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> > Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> > Cc: David Airlie <airlied@xxxxxxxxx>
> > Cc: Simona Vetter <simona@xxxxxxxx>
> > ---
> >  drivers/gpu/drm/xe/xe_guc_pagefault.c   |  5 ++++-
> >  drivers/gpu/drm/xe/xe_pagefault.c       | 23 +++++++++++++++--------
> >  drivers/gpu/drm/xe/xe_pagefault_types.h |  9 +++++++--
> >  3 files changed, 26 insertions(+), 11 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_guc_pagefault.c b/drivers/gpu/drm/xe/xe_guc_pagefault.c
> > index 607e32392f46..7d24bd828e5b 100644
> > --- a/drivers/gpu/drm/xe/xe_guc_pagefault.c
> > +++ b/drivers/gpu/drm/xe/xe_guc_pagefault.c
> > @@ -78,7 +78,10 @@ int xe_guc_pagefault_handler(struct xe_guc *guc, u32 *msg, u32 len)
> >  				      << PFD_VIRTUAL_ADDR_HI_SHIFT) |
> >  		(FIELD_GET(PFD_VIRTUAL_ADDR_LO, msg[2]) <<
> >  		 PFD_VIRTUAL_ADDR_LO_SHIFT);
> > -	pf.consumer.asid = FIELD_GET(PFD_ASID, msg[1]);
> 
> Maybe a BUILD_ON_BUG(XE_MAX_ASID > XE_PAGEFAULT_ASID_MASK);
> 
> > +	pf.consumer.id = FIELD_PREP(XE_PAGEFAULT_ASID_MASK,
> > +				    FIELD_GET(PFD_ASID, msg[1])) |
> > +			 FIELD_PREP(XE_PAGEFAULT_SRCID_MASK,
> > +				    FIELD_GET(PFD_SRC_ID, msg[0]));
> >  	pf.consumer.access_type = FIELD_GET(PFD_ACCESS_TYPE, msg[2]) |
> >  		(FIELD_GET(PFD_PREFETCH, msg[2]) ? XE_PAGEFAULT_ACCESS_PREFETCH : 0);
> >  	if (FIELD_GET(XE2_PFD_TRVA_FAULT, msg[0]))
> > diff --git a/drivers/gpu/drm/xe/xe_pagefault.c b/drivers/gpu/drm/xe/xe_pagefault.c
> > index dd3c068e1a39..2a21203b1a2a 100644
> > --- a/drivers/gpu/drm/xe/xe_pagefault.c
> > +++ b/drivers/gpu/drm/xe/xe_pagefault.c
> > @@ -169,6 +169,7 @@ static struct xe_vm *xe_pagefault_asid_to_vm(struct xe_device *xe, u32 asid)
> >  
> >  static int xe_pagefault_service(struct xe_pagefault *pf)
> >  {
> > +	u32 asid = FIELD_GET(XE_PAGEFAULT_ASID_MASK, pf->consumer.id);
> 
> Nit: can you move this below the struct stack variables.
> 
> >  	struct xe_gt *gt = pf->gt;
> >  	struct xe_device *xe = gt_to_xe(gt);
> >  	struct xe_vm *vm;
> > @@ -180,7 +181,7 @@ static int xe_pagefault_service(struct xe_pagefault *pf)
> >  	if (pf->consumer.fault_type_level == XE_PAGEFAULT_TYPE_LEVEL_NACK)
> >  		return -EFAULT;
> >  
> > -	vm = xe_pagefault_asid_to_vm(xe, pf->consumer.asid);
> > +	vm = xe_pagefault_asid_to_vm(xe, asid);
> >  	if (IS_ERR(vm))
> >  		return PTR_ERR(vm);
> >  
> > @@ -242,14 +243,16 @@ static bool xe_pagefault_queue_pop(struct xe_pagefault_queue *pf_queue,
> >  
> >  static void xe_pagefault_print(struct xe_pagefault *pf)
> >  {
> > -	xe_gt_info(pf->gt, "\n\tASID: %d\n"
> > +	xe_gt_info(pf->gt, "\n\tASID: %ld\n"
> >  		   "\tFaulted Address: 0x%08x%08x\n"
> >  		   "\tFaultType: %lu\n"
> >  		   "\tAccessType: %lu\n"
> >  		   "\tFaultLevel: %lu\n"
> >  		   "\tEngineClass: %d %s\n"
> > -		   "\tEngineInstance: %d\n",
> > -		   pf->consumer.asid,
> > +		   "\tEngineInstance: %d\n"
> > +		   "\tSRCID: 0x%02lx\n",
> > +		   FIELD_GET(XE_PAGEFAULT_ASID_MASK,
> > +			     pf->consumer.id),
> >  		   upper_32_bits(pf->consumer.page_addr),
> >  		   lower_32_bits(pf->consumer.page_addr),
> >  		   FIELD_GET(XE_PAGEFAULT_TYPE_MASK,
> > @@ -260,7 +263,9 @@ static void xe_pagefault_print(struct xe_pagefault *pf)
> >  			     pf->consumer.fault_type_level),
> >  		   pf->consumer.engine_class,
> >  		   xe_hw_engine_class_to_str(pf->consumer.engine_class),
> > -		   pf->consumer.engine_instance);
> > +		   pf->consumer.engine_instance,
> > +		   FIELD_GET(XE_PAGEFAULT_SRCID_MASK,
> > +			     pf->consumer.id));
> >  }
> >  
> >  static void xe_pagefault_save_to_vm(struct xe_device *xe, struct xe_pagefault *pf)
> > @@ -273,7 +278,8 @@ static void xe_pagefault_save_to_vm(struct xe_device *xe, struct xe_pagefault *p
> >  	 * mode, return VM anyways.
> >  	 */
> >  	down_read(&xe->usm.lock);
> > -	vm = xa_load(&xe->usm.asid_to_vm, pf->consumer.asid);
> > +	vm = xa_load(&xe->usm.asid_to_vm,
> > +		     FIELD_GET(XE_PAGEFAULT_ASID_MASK, pf->consumer.id));
> >  	if (vm)
> >  		xe_vm_get(vm);
> >  	else
> > @@ -474,8 +480,9 @@ static bool xe_pagefault_queue_full(struct xe_pagefault_queue *pf_queue)
> >   */
> >  int xe_pagefault_handler(struct xe_device *xe, struct xe_pagefault *pf)
> >  {
> > +	u32 asid = FIELD_GET(XE_PAGEFAULT_ASID_MASK, pf->consumer.id);
> 
> Same nit as above.

The ASID value is necessary to get the initial starting position of the xe_pagefault_queue
pf_queue below, so defining it later is unviable.

I can apply basically every other suggestion, though.
-Jonathan Cavitt
 
> 
> Otherwise LGTM.
> 
> Matt
> 
> >  	struct xe_pagefault_queue *pf_queue = xe->usm.pf_queue +
> > -		(pf->consumer.asid % XE_PAGEFAULT_QUEUE_COUNT);
> > +		(asid % XE_PAGEFAULT_QUEUE_COUNT);
> >  	unsigned long flags;
> >  	bool full;
> >  
> > @@ -489,7 +496,7 @@ int xe_pagefault_handler(struct xe_device *xe, struct xe_pagefault *pf)
> >  	} else {
> >  		drm_warn(&xe->drm,
> >  			 "PageFault Queue (%d) full, shouldn't be possible\n",
> > -			 pf->consumer.asid % XE_PAGEFAULT_QUEUE_COUNT);
> > +			 asid % XE_PAGEFAULT_QUEUE_COUNT);
> >  	}
> >  	spin_unlock_irqrestore(&pf_queue->lock, flags);
> >  
> > diff --git a/drivers/gpu/drm/xe/xe_pagefault_types.h b/drivers/gpu/drm/xe/xe_pagefault_types.h
> > index c4ee625b93dd..2213cea886c7 100644
> > --- a/drivers/gpu/drm/xe/xe_pagefault_types.h
> > +++ b/drivers/gpu/drm/xe/xe_pagefault_types.h
> > @@ -65,8 +65,13 @@ struct xe_pagefault {
> >  	struct {
> >  		/** @consumer.page_addr: address of page fault */
> >  		u64 page_addr;
> > -		/** @consumer.asid: address space ID */
> > -		u32 asid;
> > +#define XE_PAGEFAULT_ASID_MASK	GENMASK(23, 0)
> > +#define XE_PAGEFAULT_SRCID_MASK	GENMASK(31, 24)
> > +		/**
> > +		 * @consumer.id: address space ID and SRCID, folded into one
> > +		 * to keep size compact
> > +		 */
> > +		u32 id;
> >  		/**
> >  		 * @consumer.access_type: access type and prefetch flag packed
> >  		 * into a u8.
> > -- 
> > 2.53.0
> > 
>