[PATCH 02/11] drm/xe: Implement xe_pagefault_init
Summers, Stuart
stuart.summers at intel.com
Wed Aug 6 23:08:18 UTC 2025
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.
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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