drm/i915/gt: make kobj attributes const

There's no need for any of these to be mutable, constify:

drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000020 files.0
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000050 files.1
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 preempt_timeout_attr
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 timeslice_duration_attr
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 timeslice_duration_def
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 preempt_timeout_def
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 max_spin_def
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 stop_timeout_def
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 heartbeat_interval_def
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 name_attr
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 class_attr
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 inst_attr
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 mmio_attr
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 caps_attr
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 all_caps_attr
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 max_spin_attr
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 stop_timeout_attr
drivers/gpu/drm/i915/gt/sysfs_engines.o: .data 0000000000000038 heartbeat_interval_attr

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230309081645.385650-1-jani.nikula@intel.com

drm/i915: Make kobj_type structures constant

Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.

Take advantage of this to constify the structure definitions to prevent
modification at runtime.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230216-kobj_type-i915-v1-1-ca65c9b93518@weissschuh.net

drm/i915/gt: Use sysfs_emit() and sysfs_emit_at()

Use sysfs_emit() and sysfs_emit_at() in show() callback
as recommended by Documentation/filesystems/sysfs.rst

Cc: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230130131358.16800-1-nirmoy.das@intel.com

drm/i915/guc: Limit scheduling properties to avoid overflow

GuC converts the pre-emption timeout and timeslice quantum values into
clock ticks internally. That significantly reduces the point of 32bit
overflow. On current platforms, worst case scenario is approximately
110 seconds. Rather than allowing the user to set higher values and
then get confused by early timeouts, add limits when setting these
values.

v2: Add helper functions for clamping (review feedback from Tvrtko).
v3: Add a bunch of BUG_ON range checks in addition to the checks
already in the clamping functions (Tvrtko)

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Acked-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221006213813.1563435-2-John.C.Harrison@Intel.com

drm/i915/gt: Cleanup kasan warning for on-stack (unsigned long) casting

Kasan is gving a warning for passing a u32 parameter into find_first_bit
(casting to a unsigned long *, with appropriate length restrictions):

[ 44.678262] BUG: KASAN: stack-out-of-bounds in find_first_bit+0x2e/0x50
[ 44.678295] Read of size 8 at addr ffff888233f4fc30 by task core_hotunplug/474
[ 44.678326]
[ 44.678358] CPU: 0 PID: 474 Comm: core_hotunplug Not tainted 5.9.0+ #608
[ 44.678465] Hardware name: BESSTAR (HK) LIMITED GN41/Default string, BIOS BLT-BI-MINIPC-F4G-EX3R110-GA65A-101-D 10/12/2018
[ 44.678500] Call Trace:
[ 44.678534] dump_stack+0x84/0xba
[ 44.678569] print_address_description.constprop.0+0x21/0x220
[ 44.678605] ? kmsg_dump_rewind_nolock+0x5f/0x5f
[ 44.678638] ? _raw_spin_lock_irqsave+0x6d/0xb0
[ 44.678669] ? _raw_write_lock_irqsave+0xb0/0xb0
[ 44.678702] ? set_task_cpu+0x1e0/0x1e0
[ 44.678733] ? find_first_bit+0x2e/0x50
[ 44.678763] kasan_report.cold+0x20/0x42
[ 44.678794] ? find_first_bit+0x2e/0x50
[ 44.678825] __asan_load8+0x69/0x90
[ 44.678856] find_first_bit+0x2e/0x50
[ 44.679027] __caps_show.isra.0+0x9e/0x1f0 [i915]

Since we are only using the shorter type for our own convenience,
accommodate kasan and use unsigned long.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201013110845.16127-1-chris@chris-wilson.co.uk

drm/i915: Show per-engine default property values in sysfs

By providing the default values configured into the kernel via sysfs, it
is much more convenient for userspace to restore those sane defaults, or
at least know what are considered good baseline. This is useful, for
example, to cleanup after any failed userspace prior to commencing new
jobs.

/sys/class/drm/card0/engine/rcs0/
├── capabilities
├── class
├── .defaults
│   ├── heartbeat_interval_ms
│   ├── max_busywait_duration_ns
│   ├── preempt_timeout_ms
│   ├── stop_timeout_ms
│   └── timeslice_duration_ms
├── heartbeat_interval_ms
├── instance
├── known_capabilities
├── max_busywait_duration_ns
├── mmio_base
├── name
├── preempt_timeout_ms
├── stop_timeout_ms
└── timeslice_duration_ms

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Maciej Patelczyk <maciej.patelczyk@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200514062905.28668-1-chris@chris-wilson.co.uk

drm/i915/gt: Expose heartbeat interval via sysfs

We monitor the health of the system via periodic heartbeat pulses. The
pulses also provide the opportunity to perform garbage collection.
However, we interpret an incomplete pulse (a missed heartbeat) as an
indication that the system is no longer responsive, i.e. hung, and
perform an engine or full GPU reset. Given that the preemption
granularity can be very coarse on a system, we let the sysadmin override
our legacy timeouts which were "optimised" for desktop applications.

The heartbeat interval can be adjusted per-engine using,

/sys/class/drm/card?/engine/*/heartbeat_interval_ms

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Steve Carbonari <steven.carbonari@intel.com>
Tested-by: Steve Carbonari <steven.carbonari@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228131716.3243616-7-chris@chris-wilson.co.uk

drm/i915/gt: Expose preempt reset timeout via sysfs

After initialising a preemption request, we give the current resident a
small amount of time to vacate the GPU. The preemption request is for a
higher priority context and should be immediate to maintain high
quality of service (and avoid priority inversion). However, the
preemption granularity of the GPU can be quite coarse and so we need a
compromise.

The preempt timeout can be adjusted per-engine using,

/sys/class/drm/card?/engine/*/preempt_timeout_ms

and can be disabled by setting it to 0.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Steve Carbonari <steven.carbonari@intel.com>
Tested-by: Steve Carbonari <steven.carbonari@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228131716.3243616-6-chris@chris-wilson.co.uk

drm/i915/gt: Expose reset stop timeout via sysfs

When we allow ourselves to sleep before a GPU reset after disabling
submission, even for a few milliseconds, gives an innocent context the
opportunity to clear the GPU before the reset occurs. However, how long
to sleep depends on the typical non-preemptible duration (a similar
problem to determining the ideal preempt-reset timeout or even the
heartbeat interval). As this seems of a hard policy decision, punt it to
userspace.

The timeout can be adjusted using

/sys/class/drm/card?/engine/*/stop_timeout_ms

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Reviewed-by: Steve Carbonari <steven.carbonari@intel.com>
Tested-by: Steve Carbonari <steven.carbonari@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228131716.3243616-5-chris@chris-wilson.co.uk

drm/i915/gt: Expose busywait duration to sysfs

We busywait on an inflight request (one that is currently executing on
HW, and so might complete quickly) prior to setting up an interrupt and
sleeping. The trade off is that we keep an expensive CPU core busy in
order to avoid wake up latency: where that trade off should lie is best
left to the sysadmin.

The busywait mechanism can be compiled out with

./scripts/config --set-val DRM_I915_SPIN_REQUEST 0

The maximum busywait duration can be adjusted per-engine using,

/sys/class/drm/card?/engine/*/ms_busywait_duration_ns

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Steve Carbonari <steven.carbonari@intel.com>
Tested-by: Steve Carbonari <steven.carbonari@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228131716.3243616-4-chris@chris-wilson.co.uk

drm/i915/gt: Expose timeslice duration to sysfs

Execlists uses a scheduling quantum (a timeslice) to alternate execution
between ready-to-run contexts of equal priority. This ensures that all
users (though only if they of equal importance) have the opportunity to
run and prevents livelocks where contexts may have implicit ordering due
to userspace semaphores.

The timeslicing mechanism can be compiled out with

./scripts/config --set-val DRM_I915_TIMESLICE_DURATION 0

The timeslice duration can be adjusted per-engine using,

/sys/class/drm/card?/engine/*/timeslice_duration_ms

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Steve Carbonari <steven.carbonari@intel.com>
Tested-by: Steve Carbonari <steven.carbonari@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228131716.3243616-3-chris@chris-wilson.co.uk

drm/i915/gt: Expose engine->mmio_base via sysfs

Use the per-engine sysfs directory to let userspace discover the
mmio_base of each engine. Prior to recent generations, the user
accessible registers on each engine are at a fixed offset relative to
each engine -- but require absolute addressing. As the absolute address
depends on the actual physical engine, this is not always possible to
determine from userspace (for example icl may expose vcs1 or vcs2 as the
second vcs engine). Make this easy for userspace to discover by
providing the mmio_base in sysfs.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Steve Carbonari <steven.carbonari@intel.com>
Tested-by: Steve Carbonari <steven.carbonari@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228131716.3243616-2-chris@chris-wilson.co.uk

drm/i915/gt: Expose engine properties via sysfs

Preliminary stub to add engines underneath /sys/class/drm/cardN/, so
that we can expose properties on each engine to the sysadmin.

To start with we have basic analogues of the i915_query ioctl so that we
can pretty print engine discovery from the shell, and flesh out the
directory structure. Later we will add writeable sysadmin properties such
as per-engine timeout controls.

An example tree of the engine properties on Braswell:
/sys/class/drm/card0
└── engine
   ├── bcs0
   │   ├── capabilities
   │   ├── class
   │   ├── instance
   │   ├── known_capabilities
   │   └── name
   ├── rcs0
   │   ├── capabilities
   │   ├── class
   │   ├── instance
   │   ├── known_capabilities
   │   └── name
   ├── vcs0
   │   ├── capabilities
   │   ├── class
   │   ├── instance
   │   ├── known_capabilities
   │   └── name
   └── vecs0
      ├── capabilities
   ├── class
   ├── instance
      ├── known_capabilities
   └── name

v2: Include stringified capabilities
v3: Include all known capabilities for futureproofing.
v4: Combine the two caps loops into one

v5: Hide underneath Kconfig.unstable for wider discussion

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Tested-by: Steve Carbonari <steven.carbonari@intel.com>
Reviewed-by: Steve Carbonari <steven.carbonari@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228131716.3243616-1-chris@chris-wilson.co.uk