linux-kernel - [PATCH 0/6] Two-pass MMU interval notifiers

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Message-ID: <20250821114626.89818-1-thomas.hellstrom@linux.intel.com>
Date: Thu, 21 Aug 2025 13:46:20 +0200
From: Thomas Hellström <thomas.hellstrom@...ux.intel.com>
To: intel-xe@...ts.freedesktop.org
Cc: Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	Matthew Brost <matthew.brost@...el.com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Simona Vetter <simona.vetter@...ll.ch>,
	Dave Airlie <airlied@...il.com>,
	Alistair Popple <apopple@...dia.com>,
	dri-devel@...ts.freedesktop.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Christian König <christian.koenig@....com>
Subject: [PATCH 0/6] Two-pass MMU interval notifiers

GPU use-cases for mmu_interval_notifiers with hmm often involve
starting a gpu operation and then waiting for it to complete.
These operations are typically context preemption or TLB flushing.

With single-pass notifiers per GPU this doesn't scale in
multi-gpu scenarios. In those scenarios we'd want to first start
preemption- or TLB flushing on all GPUs and as a second pass wait
for them to complete.

One can do this on per-driver basis multiplexing per-driver
notifiers but that would mean sharing the notifier "user" lock
across all GPUs and that doesn't scale well either, so adding support
for two-pass in the core appears like the right choice.

So this series does that, with pach 1 implementing the core support
and also describes the choices made.
The rest of the patches implements a POC with drm_gpusvm, but this
will also come in handy for things like userptr where waiting for
bind completion, starting of preemption and waiting for
preemption completion can pe pipelined across GPUs.

Cc: Matthew Brost <matthew.brost@...el.com>
Cc: Jason Gunthorpe <jgg@...pe.ca>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Simona Vetter <simona.vetter@...ll.ch>
Cc: Dave Airlie <airlied@...il.com>
Cc: Alistair Popple <apopple@...dia.com>
Cc: <dri-devel@...ts.freedesktop.org>
Cc: <linux-mm@...ck.org>
Cc: <linux-kernel@...r.kernel.org>

Matthew Brost (5):
  drm/gpusvm, drm/xe: Update GPU SVM / Xe to twopass MMU notifier
  drm/gpusvm: Add drm_gpusvm_in_notifier_* helpers
  drm/xe: Skip waiting on unarmed fences in
    xe_gt_tlb_invalidation_fence_wait
  drm/xe: Add fences argument to xe_vm_range_tilemask_tlb_invalidation
  drm/xe: Implement two pass MMU notifiers for SVM

Thomas Hellström (1):
  mm/mmu_notifier: Allow two-pass struct mmu_interval_notifiers

 drivers/gpu/drm/drm_gpusvm.c                | 18 +++--
 drivers/gpu/drm/xe/xe_gt_tlb_invalidation.h |  3 +-
 drivers/gpu/drm/xe/xe_svm.c                 | 83 +++++++++++++++++----
 drivers/gpu/drm/xe/xe_vm.c                  | 26 ++++---
 drivers/gpu/drm/xe/xe_vm.h                  |  6 +-
 include/drm/drm_gpusvm.h                    | 33 ++++++--
 include/linux/mmu_notifier.h                | 42 +++++++++++
 mm/mmu_notifier.c                           | 63 +++++++++++++---
 8 files changed, 224 insertions(+), 50 deletions(-)

-- 
2.50.1