[PATCH 02/11] drm/xe: Implement xe_pagefault_init
Summers, Stuart
stuart.summers at intel.com
Thu Aug 7 18:22:39 UTC 2025
On Wed, 2025-08-06 at 16:59 -0700, Matthew Brost wrote:
> On Wed, Aug 06, 2025 at 05:08:18PM -0600, Summers, Stuart wrote:
> > On Tue, 2025-08-05 at 23:22 -0700, Matthew Brost wrote:
> > > Create pagefault queues and initialize them.
> > >
> > > Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> > > ---
> > > drivers/gpu/drm/xe/xe_device.c | 5 ++
> > > drivers/gpu/drm/xe/xe_device_types.h | 6 ++
> > > drivers/gpu/drm/xe/xe_pagefault.c | 93
> > > +++++++++++++++++++++++++++-
> > > 3 files changed, 102 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/xe/xe_device.c
> > > b/drivers/gpu/drm/xe/xe_device.c
> > > index 57edbc63da6f..c7c8aee03841 100644
> > > --- a/drivers/gpu/drm/xe/xe_device.c
> > > +++ b/drivers/gpu/drm/xe/xe_device.c
> > > @@ -50,6 +50,7 @@
> > > #include "xe_nvm.h"
> > > #include "xe_oa.h"
> > > #include "xe_observation.h"
> > > +#include "xe_pagefault.h"
> > > #include "xe_pat.h"
> > > #include "xe_pcode.h"
> > > #include "xe_pm.h"
> > > @@ -890,6 +891,10 @@ int xe_device_probe(struct xe_device *xe)
> > > if (err)
> > > return err;
> > >
> > > + err = xe_pagefault_init(xe);
> > > + if (err)
> > > + return err;
> > > +
> > > xe_nvm_init(xe);
> > >
> > > err = xe_heci_gsc_init(xe);
> > > diff --git a/drivers/gpu/drm/xe/xe_device_types.h
> > > b/drivers/gpu/drm/xe/xe_device_types.h
> > > index 01e8fa0d2f9f..6aa119026ce9 100644
> > > --- a/drivers/gpu/drm/xe/xe_device_types.h
> > > +++ b/drivers/gpu/drm/xe/xe_device_types.h
> > > @@ -17,6 +17,7 @@
> > > #include "xe_lmtt_types.h"
> > > #include "xe_memirq_types.h"
> > > #include "xe_oa_types.h"
> > > +#include "xe_pagefault_types.h"
> > > #include "xe_platform_types.h"
> > > #include "xe_pmu_types.h"
> > > #include "xe_pt_types.h"
> > > @@ -394,6 +395,11 @@ struct xe_device {
> > > u32 next_asid;
> > > /** @usm.lock: protects UM state */
> > > struct rw_semaphore lock;
> > > + /** @usm.pf_wq: page fault work queue, unbound,
> > > high
> > > priority */
> > > + struct workqueue_struct *pf_wq;
> > > +#define XE_PAGEFAULT_QUEUE_COUNT 4
> > > + /** @pf_queue: Page fault queues */
> > > + struct xe_pagefault_queue
> > > pf_queue[XE_PAGEFAULT_QUEUE_COUNT];
> > > } usm;
> > >
> > > /** @pinned: pinned BO state */
> > > diff --git a/drivers/gpu/drm/xe/xe_pagefault.c
> > > b/drivers/gpu/drm/xe/xe_pagefault.c
> > > index 3ce0e8d74b9d..14304c41eb23 100644
> > > --- a/drivers/gpu/drm/xe/xe_pagefault.c
> > > +++ b/drivers/gpu/drm/xe/xe_pagefault.c
> > > @@ -3,6 +3,10 @@
> > > * Copyright © 2025 Intel Corporation
> > > */
> > >
> > > +#include <drm/drm_managed.h>
> > > +
> > > +#include "xe_device.h"
> > > +#include "xe_gt_types.h"
> > > #include "xe_pagefault.h"
> > > #include "xe_pagefault_types.h"
> > >
> > > @@ -19,6 +23,71 @@
> > > * with a single shared consumer.
> > > */
> > >
> > > +static int xe_pagefault_entry_size(void)
> > > +{
> > > + return roundup_pow_of_two(sizeof(struct xe_pagefault));
> >
> > Nice thanks!
> >
> > > +}
> > > +
> > > +static void xe_pagefault_queue_work(struct work_struct *w)
> > > +{
> > > + /* TODO: Implement */
> > > +}
> > > +
> > > +static int xe_pagefault_queue_init(struct xe_device *xe,
> > > + struct xe_pagefault_queue
> > > *pf_queue)
> > > +{
> > > + struct xe_gt *gt;
> > > + int total_num_eus = 0;
> > > + u8 id;
> > > +
> > > + for_each_gt(gt, xe, id) {
> > > + xe_dss_mask_t all_dss;
> > > + int num_dss, num_eus;
> > > +
> > > + bitmap_or(all_dss, gt->fuse_topo.g_dss_mask,
> > > + gt->fuse_topo.c_dss_mask,
> > > XE_MAX_DSS_FUSE_BITS);
> > > +
> > > + num_dss = bitmap_weight(all_dss,
> > > XE_MAX_DSS_FUSE_BITS);
> > > + num_eus = bitmap_weight(gt-
> > > > fuse_topo.eu_mask_per_dss,
> > > + XE_MAX_EU_FUSE_BITS) *
> > > num_dss;
> > > +
> > > + total_num_eus += num_eus;
> >
> > I'm behind on that patch I had posted a while back to update this
> > algorithm :(. Want to pull that calculation in here directly so we
> > can
> > remove the PF_MULTIPLIER you have below?
> >
> > See
> > https://patchwork.freedesktop.org/patch/651415/?series=148523&rev=1
> >
> > I can also rework that on top of this if you'd prefer, either way
> > is
> > fine with me.
> >
>
> Either way works for me. If you get this one in ahead of me, no
> issuing
> picking it up in a rebase or ofc if lands first you can post on top
> of
> this. If you are concerned about history, then the later might be
> better.
Ok I'll hold off pushing mine back to the list until you're done. I was
also suggesting you could just pull my changes into your patch if you
wanted, although maybe that complicates what is mostly an internal
interface update here with more functional-focused changes. But if you
decide not to do that I'll just wait until yours land and pull it in on
top.
Thanks,
Stuart
>
> Matt
>
> > Thanks,
> > Stuart
> >
> > > + }
> > > +
> > > + xe_assert(xe, total_num_eus);
> > > +
> > > + /*
> > > + * user can issue separate page faults per EU and per CS
> > > + *
> > > + * XXX: Multiplier required as compute UMD are getting PF
> > > queue errors
> > > + * without it. Follow on why this multiplier is required.
> > > + */
> > > +#define PF_MULTIPLIER 8
> > > + pf_queue->size = (total_num_eus + XE_NUM_HW_ENGINES) *
> > > + xe_pagefault_entry_size() * PF_MULTIPLIER;
> > > + pf_queue->size = roundup_pow_of_two(pf_queue->size);
> > > +#undef PF_MULTIPLIER
> > > +
> > > + drm_dbg(&xe->drm, "xe_pagefault_entry_size=%d,
> > > total_num_eus=%d, pf_queue->size=%u",
> > > + xe_pagefault_entry_size(), total_num_eus,
> > > pf_queue-
> > > > size);
> > > +
> > > + pf_queue->data = devm_kzalloc(xe->drm.dev, pf_queue-
> > > >size,
> > > GFP_KERNEL);
> > > + if (!pf_queue->data)
> > > + return -ENOMEM;
> > > +
> > > + spin_lock_init(&pf_queue->lock);
> > > + INIT_WORK(&pf_queue->worker, xe_pagefault_queue_work);
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static void xe_pagefault_fini(void *arg)
> > > +{
> > > + struct xe_device *xe = arg;
> > > +
> > > + destroy_workqueue(xe->usm.pf_wq);
> > > +}
> > > +
> > > /**
> > > * xe_pagefault_init() - Page fault init
> > > * @xe: xe device instance
> > > @@ -29,8 +98,28 @@
> > > */
> > > int xe_pagefault_init(struct xe_device *xe)
> > > {
> > > - /* TODO - implement */
> > > - return 0;
> > > + int err, i;
> > > +
> > > + if (!xe->info.has_usm)
> > > + return 0;
> > > +
> > > + xe->usm.pf_wq =
> > > alloc_workqueue("xe_page_fault_work_queue",
> > > + WQ_UNBOUND | WQ_HIGHPRI,
> > > + XE_PAGEFAULT_QUEUE_COUNT)
> > > ;
> > > + if (!xe->usm.pf_wq)
> > > + return -ENOMEM;
> > > +
> > > + for (i = 0; i < XE_PAGEFAULT_QUEUE_COUNT; ++i) {
> > > + err = xe_pagefault_queue_init(xe, xe-
> > > >usm.pf_queue +
> > > i);
> > > + if (err)
> > > + goto err_out;
> > > + }
> > > +
> > > + return devm_add_action_or_reset(xe->drm.dev,
> > > xe_pagefault_fini, xe);
> > > +
> > > +err_out:
> > > + destroy_workqueue(xe->usm.pf_wq);
> > > + return err;
> > > }
> > >
> > > /**
> >
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