sched_ext: Maintain an online cid mask in the scheduler arenagrafted

Schedulers on the default cid mapping treat [0, nr_online_cids) as the
online set and restart on hotplug. Schedulers that install their own mapping
with scx_bpf_cid_override() have no way to learn which cids are online: the
count no longer identifies members and the CPU-form cpumask is unusable from
cid programs. This is an obvious hole in the cid API.

Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's
arena, allocated alongside the per-CPU scratch masks and populated after the
cid mapping is finalized and before ops.init(), for child schedulers too.
The pointer stays valid through ops.exit() with no reference to take. It is
the arena offset as a void pointer, the same form struct_ops arena arguments
arrive in. The verifier types the void return as a scalar for the program's
arena cast.

The mask follows the SCX hotplug notifications: seeded from cpu_active_mask
and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask
only inside a hotplug transition. Updates walk the scheduler list under the
lock that also serializes unlinking. Reads are live, not atomic snapshots.
Root initialization excludes hotplug.

v2: Reworded the getter kerneldoc (Andrea Righi).

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

20 files changed, 353 insertions, 0 deletions

diff --git a/Documentation/gpu/xe/index.rst b/Documentation/gpu/xe/index.rst
new file mode 100644
index 000000000..665c0e936
--- /dev/null
+++ b/Documentation/gpu/xe/index.rst
@@ -0,0 +1,37 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+.. _drm/xe:
+
+=======================
+drm/xe Intel GFX Driver
+=======================
+
+The drm/xe driver supports some future GFX cards with rendering, display,
+compute and media. Support for currently available platforms like TGL, ADL,
+DG2, etc is provided to prototype the driver.
+
+The display, or :ref:`drm-kms`, support for drm/xe is provided by
+:ref:`drm/intel-display`, and shared with :ref:`drm/i915 <drm/i915>`.
+
+.. toctree::
+   :titlesonly:
+
+   xe_mm
+   xe_map
+   xe_migrate
+   xe_exec_queue
+   xe_cs
+   xe_pm
+   xe_gt_freq
+   xe_pcode
+   xe_gt_mcr
+   xe_wa
+   xe_rtp
+   xe_firmware
+   xe_tile
+   xe_debugging
+   xe_devcoredump
+   xe_device
+   xe-drm-usage-stats.rst
+   xe_configfs
+   xe_gt_stats
diff --git a/Documentation/gpu/xe/xe-drm-usage-stats.rst b/Documentation/gpu/xe/xe-drm-usage-stats.rst
new file mode 100644
index 000000000..482d503ae
--- /dev/null
+++ b/Documentation/gpu/xe/xe-drm-usage-stats.rst
@@ -0,0 +1,10 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+.. _xe-usage-stats:
+
+========================================
+Xe DRM client usage stats implementation
+========================================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_drm_client.c
+   :doc: DRM Client usage stats
diff --git a/Documentation/gpu/xe/xe_configfs.rst b/Documentation/gpu/xe/xe_configfs.rst
new file mode 100644
index 000000000..7f8ec39dc
--- /dev/null
+++ b/Documentation/gpu/xe/xe_configfs.rst
@@ -0,0 +1,16 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+.. _xe_configfs:
+
+===========
+Xe Configfs
+===========
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_configfs.c
+   :doc: Xe Configfs
+
+Internal API
+============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_configfs.c
+   :internal:
diff --git a/Documentation/gpu/xe/xe_cs.rst b/Documentation/gpu/xe/xe_cs.rst
new file mode 100644
index 000000000..e379aed4f
--- /dev/null
+++ b/Documentation/gpu/xe/xe_cs.rst
@@ -0,0 +1,8 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==================
+Command submission
+==================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_exec.c
+   :doc: Execbuf (User GPU command submission)
diff --git a/Documentation/gpu/xe/xe_debugging.rst b/Documentation/gpu/xe/xe_debugging.rst
new file mode 100644
index 000000000..d65e56ff3
--- /dev/null
+++ b/Documentation/gpu/xe/xe_debugging.rst
@@ -0,0 +1,7 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=========
+Debugging
+=========
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_assert.h
diff --git a/Documentation/gpu/xe/xe_devcoredump.rst b/Documentation/gpu/xe/xe_devcoredump.rst
new file mode 100644
index 000000000..ae4ec0e34
--- /dev/null
+++ b/Documentation/gpu/xe/xe_devcoredump.rst
@@ -0,0 +1,14 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==================
+Xe Device Coredump
+==================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_devcoredump.c
+   :doc: Xe device coredump
+
+Internal API
+============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_devcoredump.c
+   :internal:
diff --git a/Documentation/gpu/xe/xe_device.rst b/Documentation/gpu/xe/xe_device.rst
new file mode 100644
index 000000000..39a937b97
--- /dev/null
+++ b/Documentation/gpu/xe/xe_device.rst
@@ -0,0 +1,10 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+.. _xe-device-wedging:
+
+==================
+Xe Device Wedging
+==================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_device.c
+   :doc: Xe Device Wedging
diff --git a/Documentation/gpu/xe/xe_exec_queue.rst b/Documentation/gpu/xe/xe_exec_queue.rst
new file mode 100644
index 000000000..870780621
--- /dev/null
+++ b/Documentation/gpu/xe/xe_exec_queue.rst
@@ -0,0 +1,34 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+===============
+Execution Queue
+===============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_exec_queue.c
+   :doc: Execution Queue
+
+Multi Queue Group
+=================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_exec_queue.c
+   :doc: Multi Queue Group
+
+.. _multi-queue-group-guc-interface:
+
+Multi Queue Group GuC interface
+===============================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_guc_submit.c
+   :doc: Multi Queue Group GuC interface
+
+Internal API
+============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_exec_queue_types.h
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_exec_queue.h
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_exec_queue.c
+   :internal:
diff --git a/Documentation/gpu/xe/xe_firmware.rst b/Documentation/gpu/xe/xe_firmware.rst
new file mode 100644
index 000000000..d3030d1c9
--- /dev/null
+++ b/Documentation/gpu/xe/xe_firmware.rst
@@ -0,0 +1,46 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+========
+Firmware
+========
+
+Firmware Layout
+===============
+
+.. kernel-doc:: drivers/gpu/drm/xe/abi/uc_fw_abi.h
+   :doc: CSS-based Firmware Layout
+
+.. kernel-doc:: drivers/gpu/drm/xe/abi/uc_fw_abi.h
+   :doc: GSC-based Firmware Layout
+
+Write Once Protected Content Memory (WOPCM) Layout
+==================================================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_wopcm.c
+   :doc: Write Once Protected Content Memory (WOPCM) Layout
+
+GuC CTB Blob
+============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_guc_ct.c
+   :doc: GuC CTB Blob
+
+GuC Power Conservation (PC)
+===========================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_guc_pc.c
+   :doc: GuC Power Conservation (PC)
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_guc_rc.c
+   :doc: GuC Render C-states (GuC RC)
+
+PCIe Gen5 Limitations
+=====================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_device_sysfs.c
+   :doc: PCIe Gen5 Limitations
+
+Internal API
+============
+
+TODO
diff --git a/Documentation/gpu/xe/xe_gt_freq.rst b/Documentation/gpu/xe/xe_gt_freq.rst
new file mode 100644
index 000000000..182d6aabe
--- /dev/null
+++ b/Documentation/gpu/xe/xe_gt_freq.rst
@@ -0,0 +1,17 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==========================
+Xe GT Frequency Management
+==========================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_gt_freq.c
+   :doc: Xe GT Frequency Management
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_gt_throttle.c
+   :doc: Xe GT Throttle
+
+Internal API
+============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_gt_freq.c
+   :internal:
diff --git a/Documentation/gpu/xe/xe_gt_mcr.rst b/Documentation/gpu/xe/xe_gt_mcr.rst
new file mode 100644
index 000000000..848c07bc3
--- /dev/null
+++ b/Documentation/gpu/xe/xe_gt_mcr.rst
@@ -0,0 +1,13 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==============================================
+GT Multicast/Replicated (MCR) Register Support
+==============================================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_gt_mcr.c
+   :doc: GT Multicast/Replicated (MCR) Register Support
+
+Internal API
+============
+
+TODO
diff --git a/Documentation/gpu/xe/xe_gt_stats.rst b/Documentation/gpu/xe/xe_gt_stats.rst
new file mode 100644
index 000000000..5ff806aba
--- /dev/null
+++ b/Documentation/gpu/xe/xe_gt_stats.rst
@@ -0,0 +1,11 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+================
+Xe GT Statistics
+================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_gt_stats.c
+   :doc: Xe GT Statistics
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_gt_stats_types.h
+   :internal:
diff --git a/Documentation/gpu/xe/xe_map.rst b/Documentation/gpu/xe/xe_map.rst
new file mode 100644
index 000000000..a098cfd2d
--- /dev/null
+++ b/Documentation/gpu/xe/xe_map.rst
@@ -0,0 +1,8 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=========
+Map Layer
+=========
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_map.h
+   :doc: Map layer
diff --git a/Documentation/gpu/xe/xe_migrate.rst b/Documentation/gpu/xe/xe_migrate.rst
new file mode 100644
index 000000000..f92faec0a
--- /dev/null
+++ b/Documentation/gpu/xe/xe_migrate.rst
@@ -0,0 +1,8 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=============
+Migrate Layer
+=============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_migrate_doc.h
+   :doc: Migrate Layer
diff --git a/Documentation/gpu/xe/xe_mm.rst b/Documentation/gpu/xe/xe_mm.rst
new file mode 100644
index 000000000..95864a450
--- /dev/null
+++ b/Documentation/gpu/xe/xe_mm.rst
@@ -0,0 +1,29 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=================
+Memory Management
+=================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_bo_doc.h
+   :doc: Buffer Objects (BO)
+
+GGTT
+====
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_ggtt.c
+   :doc: Global Graphics Translation Table (GGTT)
+
+GGTT Internal API
+-----------------
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_ggtt_types.h
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_ggtt.c
+   :internal:
+
+Pagetable building
+==================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_pt.c
+   :doc: Pagetable building
diff --git a/Documentation/gpu/xe/xe_pcode.rst b/Documentation/gpu/xe/xe_pcode.rst
new file mode 100644
index 000000000..2a4360112
--- /dev/null
+++ b/Documentation/gpu/xe/xe_pcode.rst
@@ -0,0 +1,23 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=====
+Pcode
+=====
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_pcode.c
+   :doc: PCODE
+
+Internal API
+============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_pcode.c
+   :internal:
+
+.. _xe-survivability-mode:
+
+==================
+Survivability Mode
+==================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_survivability_mode.c
+   :doc: Survivability Mode
diff --git a/Documentation/gpu/xe/xe_pm.rst b/Documentation/gpu/xe/xe_pm.rst
new file mode 100644
index 000000000..6781cdfb2
--- /dev/null
+++ b/Documentation/gpu/xe/xe_pm.rst
@@ -0,0 +1,14 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+========================
+Runtime Power Management
+========================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_pm.c
+   :doc: Xe Power Management
+
+Internal API
+============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_pm.c
+   :internal:
diff --git a/Documentation/gpu/xe/xe_rtp.rst b/Documentation/gpu/xe/xe_rtp.rst
new file mode 100644
index 000000000..7fdf4b6c1
--- /dev/null
+++ b/Documentation/gpu/xe/xe_rtp.rst
@@ -0,0 +1,20 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+=========================
+Register Table Processing
+=========================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_rtp.c
+   :doc: Register Table Processing
+
+Internal API
+============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_rtp_types.h
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_rtp.h
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_rtp.c
+   :internal:
diff --git a/Documentation/gpu/xe/xe_tile.rst b/Documentation/gpu/xe/xe_tile.rst
new file mode 100644
index 000000000..c33f68dd9
--- /dev/null
+++ b/Documentation/gpu/xe/xe_tile.rst
@@ -0,0 +1,14 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+==================
+Multi-tile Devices
+==================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_tile.c
+   :doc: Multi-tile Design
+
+Internal API
+============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_tile.c
+   :internal:
diff --git a/Documentation/gpu/xe/xe_wa.rst b/Documentation/gpu/xe/xe_wa.rst
new file mode 100644
index 000000000..f8811cc6a
--- /dev/null
+++ b/Documentation/gpu/xe/xe_wa.rst
@@ -0,0 +1,14 @@
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+====================
+Hardware workarounds
+====================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_wa.c
+   :doc: Hardware workarounds
+
+Internal API
+============
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_wa.c
+   :internal: