Re: [PATCH v3 10/25] drm/xe: Update GuC submission backend to run PT jobs

["Summers, Stuart" <stuart.summers@intel.com>]

On Fri, 2026-02-27 at 17:34 -0800, Matthew Brost wrote:
> PT jobs bypass GPU execution for the final step of a bind job, using
> the
> CPU to program the required page tables. Teach the GuC submission
> backend
> how to execute these jobs.
> 
> PT job submission is implemented in the GuC backend for simplicity. A
> follow-up patch could introduce a dedicated backend for PT jobs.

Still looking through the whole series, but standing alone, this patch
doesn't feel right to me. I don't see why we'd want to hook together
the PT update flow with the GuC backend...

Thanks,
Stuart

> 
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_guc_submit.c | 37 ++++++++++++++++++++++++++--
> --
>  drivers/gpu/drm/xe/xe_migrate.c    | 13 ++++++++++-
>  drivers/gpu/drm/xe/xe_migrate.h    |  8 +++++++
>  3 files changed, 52 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c
> b/drivers/gpu/drm/xe/xe_guc_submit.c
> index 453af51fe87b..1d6ac7a6563b 100644
> --- a/drivers/gpu/drm/xe/xe_guc_submit.c
> +++ b/drivers/gpu/drm/xe/xe_guc_submit.c
> @@ -36,8 +36,10 @@
>  #include "xe_lrc.h"
>  #include "xe_macros.h"
>  #include "xe_map.h"
> +#include "xe_migrate.h"
>  #include "xe_mocs.h"
>  #include "xe_pm.h"
> +#include "xe_pt.h"
>  #include "xe_ring_ops_types.h"
>  #include "xe_sched_job.h"
>  #include "xe_sleep.h"
> @@ -1183,6 +1185,20 @@ static void submit_exec_queue(struct
> xe_exec_queue *q, struct xe_sched_job *job)
>         }
>  }
>  
> +static bool is_pt_job(struct xe_sched_job *job)
> +{
> +       return job->is_pt_job;
> +}
> +
> +static void run_pt_job(struct xe_sched_job *job)
> +{
> +       xe_migrate_update_pgtables_cpu_execute(job->pt_update[0].vm,
> +                                              job-
> >pt_update[0].tile,
> +                                              job->pt_update[0].ops,
> +                                              job-
> >pt_update[0].pt_job_ops->ops,
> +                                              job-
> >pt_update[0].pt_job_ops->current_op);
> +}
> +
>  static struct dma_fence *
>  guc_exec_queue_run_job(struct drm_sched_job *drm_job)
>  {
> @@ -1210,14 +1226,25 @@ guc_exec_queue_run_job(struct drm_sched_job
> *drm_job)
>                                 register_exec_queue(primary,
> GUC_CONTEXT_NORMAL);
>                 }
>  
> -               if (!exec_queue_registered(q))
> -                       register_exec_queue(q, GUC_CONTEXT_NORMAL);
> -               if (!job->restore_replay)
> -                       q->ring_ops->emit_job(job);
> -               submit_exec_queue(q, job);
> +               if (is_pt_job(job)) {
> +                       xe_gt_assert(guc_to_gt(guc),
> !exec_queue_registered(q));
> +                       run_pt_job(job);
> +               } else {
> +                       if (!exec_queue_registered(q))
> +                               register_exec_queue(q,
> GUC_CONTEXT_NORMAL);
> +                       if (!job->restore_replay)
> +                               q->ring_ops->emit_job(job);
> +                       submit_exec_queue(q, job);
> +               }
>                 job->restore_replay = false;
>         }
>  
> +       if (is_pt_job(job)) {
> +               xe_pt_job_ops_put(job->pt_update[0].pt_job_ops);
> +               dma_fence_put(job->fence);      /* Drop ref from
> xe_sched_job_arm */
> +               return NULL;
> +       }
> +
>  run_job_out:
>  
>         return job->fence;
> diff --git a/drivers/gpu/drm/xe/xe_migrate.c
> b/drivers/gpu/drm/xe/xe_migrate.c
> index cd6802642ef3..e9b9dfe19e48 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.c
> +++ b/drivers/gpu/drm/xe/xe_migrate.c
> @@ -1715,7 +1715,18 @@ struct migrate_test_params {
>         container_of(_priv, struct migrate_test_params, base)
>  #endif
>  
> -static void
> +/**
> + * xe_migrate_update_pgtables_cpu_execute() - Update a VM's PTEs via
> the CPU
> + * @vm: The VM being updated
> + * @tile: The tile being updated
> + * @ops: The migrate PT update ops
> + * @pt_ops: The VM PT update ops
> + * @num_ops: The number of The VM PT update ops
> + *
> + * Execute the VM PT update ops array which results in a VM's PTEs
> being updated
> + * via the CPU.
> + */
> +void
>  xe_migrate_update_pgtables_cpu_execute(struct xe_vm *vm, struct
> xe_tile *tile,
>                                        const struct
> xe_migrate_pt_update_ops *ops,
>                                        struct xe_vm_pgtable_update_op
> *pt_op,
> diff --git a/drivers/gpu/drm/xe/xe_migrate.h
> b/drivers/gpu/drm/xe/xe_migrate.h
> index c3c0740f908d..30c9c990a8b1 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.h
> +++ b/drivers/gpu/drm/xe/xe_migrate.h
> @@ -24,6 +24,7 @@ struct xe_pt;
>  struct xe_tile;
>  struct xe_vm;
>  struct xe_vm_pgtable_update;
> +struct xe_vm_pgtable_update_op;
>  struct xe_vma;
>  
>  enum xe_sriov_vf_ccs_rw_ctxs;
> @@ -157,6 +158,13 @@ struct dma_fence *xe_migrate_clear(struct
> xe_migrate *m,
>  
>  struct xe_vm *xe_migrate_get_vm(struct xe_migrate *m);
>  
> +
> +void
> +xe_migrate_update_pgtables_cpu_execute(struct xe_vm *vm, struct
> xe_tile *tile,
> +                                      const struct
> xe_migrate_pt_update_ops *ops,
> +                                      struct xe_vm_pgtable_update_op
> *pt_op,
> +                                      int num_ops);
> +
>  struct dma_fence *
>  xe_migrate_update_pgtables(struct xe_migrate *m,
>                            struct xe_migrate_pt_update *pt_update);