[PATCH v3 0/4] Two-pass MMU interval notifiers

Thomas Hellström
2026-03-03T13:34:47Z

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.

This also applies in non-recoverable page-fault scenarios to
starting a preemption requests on GPUs and waiting for the GPUs
to preempt so that system pages they access can be reclaimed.

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 xeKMD userptr
invalidation and potential TLB-flushing. A follow-up series
will extend to drm_gpusvm.

v2 hightlights:
- Refactor the core mm patch to use the struct
mmu_interval_notifier_ops for the invalidate_finish() callback.
- Rebase on xe driver tlb invalidation changes.
- Provide an initial implementation for userptr instead of drm_gpusvm.
The intent is to handle drm_gpusvm in a follow-up series.

v3:
- Address review comments from Matt Brost: Code formatting,
documentation, additional asserts and removal of
unnecessary waits, as specified in each patch.

Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Simona Vetter <simona.vetter@ffwll.ch>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: <dri-devel@lists.freedesktop.org>
Cc: <linux-mm@kvack.org>
Cc: <linux-kernel@vger.kernel.org>

Thomas Hellström (4):
mm/mmu_notifier: Allow two-pass struct mmu_interval_notifiers
drm/xe/userptr: Convert invalidation to two-pass MMU notifier
drm/xe: Split TLB invalidation into submit and wait steps
drm/xe/userptr: Defer Waiting for TLB invalidation to the second pass
if possible

drivers/gpu/drm/xe/xe_svm.c | 8 +-
drivers/gpu/drm/xe/xe_tlb_inval.c | 84 +++++++++++++
drivers/gpu/drm/xe/xe_tlb_inval.h | 6 +
drivers/gpu/drm/xe/xe_tlb_inval_types.h | 14 +++
drivers/gpu/drm/xe/xe_userptr.c | 155 ++++++++++++++++++++----
drivers/gpu/drm/xe/xe_userptr.h | 31 ++++-
drivers/gpu/drm/xe/xe_vm.c | 99 +++++----------
drivers/gpu/drm/xe/xe_vm.h | 5 +-
drivers/gpu/drm/xe/xe_vm_madvise.c | 10 +-
drivers/gpu/drm/xe/xe_vm_types.h | 1 +
include/linux/mmu_notifier.h | 38 ++++++
mm/mmu_notifier.c | 65 ++++++++--
12 files changed, 412 insertions(+), 104 deletions(-)

--
2.53.0