drm/i915: Only setup private tmpfs mount when needed and fix logging

If i915 does not want to use huge pages there is a) no point in setting up
the private mount and b) should former fail, it is misleading to log THP
support is disabled in the caller, which does not even know if callee
tried to enable it.

Fix both by restructuring the flow in i915_gemfs_init and at the same time
note the failure to set it up in all cases.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Eero Tamminen <eero.t.tamminen@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220429100414.647857-2-tvrtko.ursulin@linux.intel.com

drm/i915: Enable THP on Icelake and beyond

We have a statement from HW designers that the GPU read regression when
using 2M pages was fixed from Icelake onwards, which was also confirmed
by bencharking Eero did last year:

"""
When IOMMU is disabled, enabling THP causes following perf changes on
TGL-H (GT1):

10-15% SynMark Batch[0-3]
5-10% MemBW GPU texture, SynMark ShMapVsm
3-5% SynMark TerrainFly* + Geom* + Fill* + CSCloth + Batch4
1-3% GpuTest Triangle, SynMark TexMem* + DeferredAA + Batch[5-7]
+ few others
-7% MemBW GPU blend

In the above 3D benchmark names, * means all the variants of tests with
the same prefix. For example "SynMark TexMem*", means both TexMem128 &
TexMem512 tests in the synthetic (Intel internal) SynMark test suite.

In the (public, but proprietary) GfxBench & GLB(enchmark) test suites,
there are both onscreen and offscreen variants of each test. Unless
explicitly stated otherwise, numbers are for both variants.

All tests are run with FullHD monitor. All tests are fullscreen except
for GLB and GpuTest ones, which are run in 1/2 screen window (GpuTest
triangle is run both in fullscreen and 1/2 screen window).
"""

Since the only regression is MemBW GPU blend, against many more gains,
it sounds it is time to enable THP on Gen11+.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
References: https://gitlab.freedesktop.org/drm/intel/-/issues/430
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Eero Tamminen <eero.t.tamminen@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220429100414.647857-1-tvrtko.ursulin@linux.intel.com

drm/i915: Move intel_vtd_active and run_as_guest to i915_utils

Continuation of the effort to declutter i915_drv.h.

Also, component specific helpers which consult the iommu/virtualization
helpers moved to respective component source/header files as appropriate.

v2:
* s/dev_priv/i915/ in intel_scanout_needs_vtd_wa. (Lucas)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220329090204.2324499-1-tvrtko.ursulin@linux.intel.com
[tursulin: fixup conflict in i915_drv.h]

drm/i915: Use per device iommu check

With both integrated and discrete Intel GPUs in a system, the current
global check of intel_iommu_gfx_mapped, as done from intel_vtd_active()
may not be completely accurate.

In this patch we add i915 parameter to intel_vtd_active() in order to
prepare it for multiple GPUs and we also change the check away from Intel
specific intel_iommu_gfx_mapped (global exported by the Intel IOMMU
driver) to probing the presence of IOMMU on a specific device using
device_iommu_mapped().

This will return true both for IOMMU pass-through and address translation
modes which matches the current behaviour. If in the future we wanted to
distinguish between these two modes we could either use
iommu_get_domain_for_dev() and check for __IOMMU_DOMAIN_PAGING bit
indicating address translation, or ask for a new API to be exported from
the IOMMU core code.

v2:
* Check for dmar translation specifically, not just iommu domain. (Baolu)

v3:
* Go back to plain "any domain" check for now, rewrite commit message.

v4:
* Use device_iommu_mapped. (Robin, Baolu)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211126141424.493753-1-tvrtko.ursulin@linux.intel.com

drm/i915/gemfs: don't mark huge_opt as static

vfs_kernel_mount() modifies the passed in mount options, leaving us with
"huge", instead of "huge=within_size". Normally this shouldn't matter
with the usual module load/unload flow, however with the core_hotunplug
IGT we are hitting the following, when re-probing the memory regions:

i915 0000:00:02.0: [drm] Transparent Hugepage mode 'huge'
tmpfs: Bad value for 'huge'
[drm] Unable to create a private tmpfs mount, hugepage support will be disabled(-22).

References: https://gitlab.freedesktop.org/drm/intel/-/issues/4651
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211126110843.2028582-1-matthew.auld@intel.com

drm/i915: Use Transparent Hugepages when IOMMU is enabled

Usage of Transparent Hugepages was disabled in 9987da4b5dcf
("drm/i915: Disable THP until we have a GPU read BW W/A"), but since it
appears majority of performance regressions reported with an enabled IOMMU
can be almost eliminated by turning them on, lets just do that.

To err on the side of safety we keep the current default in cases where
IOMMU is not active, and only when it is default to the "huge=within_size"
mode. Although there probably would be wins to enable them throughout,
more extensive testing across benchmarks and platforms would need to be
done.

With the patch and IOMMU enabled my local testing on a small Skylake part
shows OglVSTangent regression being reduced from ~14% (IOMMU on versus
IOMMU off) to ~2% (same comparison but with THP on).

More detailed testing done in the below referenced Gitlab issue by Eero:

Skylake GT4e:

Performance drops from enabling IOMMU:

30-35% SynMark CSDof
20-25% Unigine Heaven, MemBW GPU write, SynMark VSTangent
~20% GLB Egypt (1/2 screen window)
10-15% GLB T-Rex (1/2 screen window)
8-10% GfxBench T-Rex, MemBW GPU blit
7-8% SynMark DeferredAA + TerrainFly* + ZBuffer
6-7% GfxBench Manhattan 3.0 + 3.1, SynMark TexMem128 & CSCloth
5-6% GfxBench CarChase, Unigine Valley
3-5% GfxBench Vulkan & GL AztecRuins + ALU2, MemBW GPU texture,
SynMark Fill*, Deferred, TerrainPan*
1-2% Most of the other tests

With the patch drops become:

20-25% SynMark TexMem*
15-20% GLB Egypt (1/2 screen window)
10-15% GLB T-Rex (1/2 screen window)
4-7% GfxBench T-Rex, GpuTest Triangle
1-8% GfxBench ALU2 (offscreen 1%, onscreen 8%)
3% GfxBench Manhattan 3.0, SynMark CSDof
2-3% Unigine Heaven + Valley, MemBW GPU texture
1-3 GfxBench Manhattan 3.1 + CarChase + Vulkan & GL AztecRuins

Broxton:

Performance drops from IOMMU, without patch:

30% MemBW GPU write
25% SynMark ZBuffer + Fill*
20% MemBW GPU blit
15% MemBW GPU blend, GpuTest Triangle
10-15% MemBW GPU texture
10% GLB Egypt, Unigine Heaven (had hangs), SynMark TerrainFly*
7-9% GLB T-Rex, GfxBench Manhattan 3.0 + T-Rex,
SynMark Deferred* + TexMem*
6-8% GfxBench CarChase, Unigine Valley,
SynMark CSCloth + ShMapVsm + TerrainPan*
5-6% GfxBench Manhattan 3.1 + GL AztecRuins,
SynMark CSDof + TexFilterTri
2-4% GfxBench ALU2, SynMark DrvRes + GSCloth + ShMapPcf + Batch[0-5] +
TexFilterAniso, GpuTest GiMark + 32-bit Julia

And with patch:

15-20% MemBW GPU texture
10% SynMark TexMem*
8-9% GLB Egypt (1/2 screen window)
4-5% GLB T-Rex (1/2 screen window)
3-6% GfxBench Manhattan 3.0, GpuTest FurMark,
SynMark Deferred + TexFilterTri
3-4% GfxBench Manhattan 3.1 + T-Rex, SynMark VSInstancing
2-4% GpuTest Triangle, SynMark DeferredAA
2-3% Unigine Heaven + Valley
1-3% SynMark Terrain*
1-2% GfxBench CarChase, SynMark TexFilterAniso + ZBuffer

Tigerlake-H:

20-25% MemBW GPU texture
15-20% GpuTest Triangle
13-15% SynMark TerrainFly* + DeferredAA + HdrBloom
8-10% GfxBench Manhattan 3.1, SynMark TerrainPan* + DrvRes
6-7% GfxBench Manhattan 3.0, SynMark TexMem*
4-8% GLB onscreen Fill + T-Rex + Egypt (more in onscreen than
offscreen versions of T-Rex/Egypt)
4-6% GfxBench CarChase + GLES AztecRuins + ALU2, GpuTest 32-bit Julia,
SynMark CSDof + DrvState
3-5% GfxBench T-Rex + Egypt, Unigine Heaven + Valley, GpuTest Plot3D
1-7% Media tests
2-3% MemBW GPU blit
1-3% Most of the rest of 3D tests

With the patch:

6-8% MemBW GPU blend => the only regression in these tests (compared
to IOMMU without THP)
4-6% SynMark DrvState (not impacted) + HdrBloom (improved)
3-4% GLB T-Rex
~3% GLB Egypt, SynMark DrvRes
1-3% GfxBench T-Rex + Egypt, SynMark TexFilterTri
1-2% GfxBench CarChase + GLES AztecRuins, Unigine Valley,
GpuTest Triangle
~1% GfxBench Manhattan 3.0/3.1, Unigine Heaven

Perf of several tests actually improved with IOMMU + THP, compared to no
IOMMU / no THP:

10-15% SynMark Batch[0-3]
5-10% MemBW GPU texture, SynMark ShMapVsm
3-4% SynMark Fill* + Geom*
2-3% SynMark TexMem512 + CSCloth
1-2% SynMark TexMem128 + DeferredAA

As a summary across all platforms, these are the benchmarks where enabling
THP on top of IOMMU enabled brings regressions:

* Skylake GT4e:
20-25% SynMark TexMem*
(whereas all MemBW GPU tests either improve or are not affected)

* Broxton J4205:
7% MemBW GPU texture
2-3% SynMark TexMem*

* Tigerlake-H:
7% MemBW GPU blend

Other benchmarks show either lowering of regressions or improvements.

v2:
* Add Kconfig dependency to transparent hugepages and some help text.
* Move to helper for easier handling of kernel build options.

v3:
* Drop Kconfig. (Daniel)

v4:
* Add some benchmark results to commit message.

v5:
* Add explicit regression summary to commit message. (Eero)

References: b901bb89324a ("drm/i915/gemfs: enable THP")
References: 9987da4b5dcf ("drm/i915: Disable THP until we have a GPU read BW W/A")
References: https://gitlab.freedesktop.org/drm/intel/-/issues/430
Co-developed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Eero Tamminen <eero.t.tamminen@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909114448.508493-1-tvrtko.ursulin@linux.intel.com

drm/i915: Stop reconfiguring our shmemfs mountpoint

The filesystem reconfigure API is undergoing a transition, breaking our
current code. As we only set the default options, we can simply remove
the call to s_op->remount_fs(). In the future, when HW permits, we can
try re-enabling huge page support, albeit as suggested with new per-file
controls.

Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190808172226.18306-1-chris@chris-wilson.co.uk

drm/i915: Move more GEM objects under gem/

Continuing the theme of separating out the GEM clutter.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528092956.14910-8-chris@chris-wilson.co.uk