Avoid rc6 counter going backward in close to 0% RC6 scenarios like:
15.005477996 114,246,613 ns i915/rc6-residency/
16.005876662 667,657 ns i915/rc6-residency/
17.006131417 7,286 ns i915/rc6-residency/
18.006615031 18,446,744,073,708,914,688 ns i915/rc6-residency/
19.007158361 18,446,744,073,709,447,168 ns i915/rc6-residency/
20.007806498 0 ns i915/rc6-residency/
21.008227495 1,440,403 ns i915/rc6-residency/
There are two aspects to this fix.
First is not assuming rc6 value zero means GT is asleep since that can
also mean GPU is fully busy and we do not want to enter the estimation
path in that case.
Second is ensuring monotonicity on the estimation path itself. I suspect
what is happening is with extremely rapid park/unpark cycles we get no
updates on the real rc6 and therefore have to careful not to
unconditionally trust use last known real rc6 when creating a new
estimation.
v2:
* Simplify logic by not tracking the estimate but last reported value.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: 16ffe73c18 ("drm/i915/pmu: Use GT parked for estimating RC6 while asleep")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> # v1
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217142057.1000-1-tvrtko.ursulin@linux.intel.com
(cherry picked from commit df6a420535)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Since commit e5dadff4b0 ("drm/i915: Protect request retirement with
timeline->mutex"), the request retirement can happen outside of the
struct_mutex serialised only by the timeline->mutex. We drop the
timeline->mutex on submitting the request (i915_request_add) so after
that point, it is liable to be freed. Make sure our local reference is
kept alive until we have finished attaching it to the signalers. (Note
that this erodes the argument that i915_request_add should consume the
reference, but that is a slightly larger patch!)
Fixes: e5dadff4b0 ("drm/i915: Protect request retirement with timeline->mutex")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217134729.3297818-1-chris@chris-wilson.co.uk
(cherry picked from commit e14177f197)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
We want the bonded request to have the same scheduler properties as its
master so that it is placed at the same depth in the queue. For example,
consider we have requests A, B and B', where B & B' are a bonded pair to
run in parallel on two engines.
A -> B
\- B'
B will run after A and so may be scheduled on an idle engine and wait on
A using a semaphore. B' sees B being executed and so enters the queue on
the same engine as A. As B' did not inherit the semaphore-chain from B,
it may have higher precedence than A and so preempts execution. However,
B' then sits on a semaphore waiting for B, who is waiting for A, who is
blocked by B.
Ergo B' needs to inherit the scheduler properties from B (i.e. the
semaphore chain) so that it is scheduled with the same priority as B and
will not be executed ahead of Bs dependencies.
Furthermore, to prevent the priorities changing via the expose fence on
B', we need to couple in the dependencies for PI. This requires us to
relax our sanity-checks that dependencies are strictly in order.
v2: Synchronise (B, B') execution on all platforms, regardless of using
a scheduler, any no-op syncs should be elided.
Fixes: ee1136908e ("drm/i915/execlists: Virtual engine bonding")
Closes: https://gitlab.freedesktop.org/drm/intel/issues/464
Testcase: igt/gem_exec_balancer/bonded-chain
Testcase: igt/gem_exec_balancer/bonded-semaphore
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/20191210151332.3902215-1-chris@chris-wilson.co.uk
(cherry picked from commit c81471f5e9)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
In order to avoid confusing the HW, we must never submit an empty ring
during lite-restore, that is we should always advance the RING_TAIL
before submitting to stay ahead of the RING_HEAD.
Normally this is prevented by keeping a couple of spare NOPs in the
request->wa_tail so that on resubmission we can advance the tail. This
relies on the request only being resubmitted once, which is the normal
condition as it is seen once for ELSP[1] and then later in ELSP[0]. On
preemption, the requests are unwound and the tail reset back to the
normal end point (as we know the request is incomplete and therefore its
RING_HEAD is even earlier).
However, if this w/a should fail we would try and resubmit the request
with the RING_TAIL already set to the location of this request's wa_tail
potentially causing a GPU hang. We can spot when we do try and
incorrectly resubmit without advancing the RING_TAIL and spare any
embarrassment by forcing the context restore.
In the case of preempt-to-busy, we leave the requests running on the HW
while we unwind. As the ring is still live, we cannot rewind our
rq->tail without forcing a reload so leave it set to rq->wa_tail and
only force a reload if we resubmit after a lite-restore. (Normally, the
forced reload will be a part of the preemption event.)
Fixes: 22b7a426bb ("drm/i915/execlists: Preempt-to-busy")
Closes: https://gitlab.freedesktop.org/drm/intel/issues/673
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: stable@kernel.vger.org
Link: https://patchwork.freedesktop.org/patch/msgid/20191209023215.3519970-1-chris@chris-wilson.co.uk
(cherry picked from commit 82c69bf586)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Pull more drm updates from Dave Airlie:
"Rob pointed out I missed his pull request for msm-next, it's been in
next for a while outside of my tree so shouldn't cause any unexpected
issues, it has some OCMEM support in drivers/soc that is acked by
other maintainers as it's outside my tree.
Otherwise it's a usual fixes pull, i915, amdgpu, the main ones, with
some tegra, omap, mgag200 and one core fix.
Summary:
msm-next:
- OCMEM support for a3xx and a4xx GPUs.
- a510 support + display support
core:
- mst payload deletion fix
i915:
- uapi alignment fix
- fix for power usage regression due to security fixes
- change default preemption timeout to 640ms from 100ms
- EHL voltage level display fixes
- TGL DGL PHY fix
- gvt - MI_ATOMIC cmd parser fix, CFL non-priv warning
- CI spotted deadlock fix
- EHL port D programming fix
amdgpu:
- VRAM lost fixes on BACO for CI/VI
- navi14 DC fixes
- misc SR-IOV, gfx10 fixes
- XGMI fixes for arcturus
- SRIOV fixes
amdkfd:
- KFD on ppc64le enabled
- page table optimisations
radeon:
- fix for r1xx/2xx register checker.
tegra:
- displayport regression fixes
- DMA API regression fixes
mgag200:
- fix devices that can't scanout except at 0 addr
omap:
- fix dma_addr refcounting"
* tag 'drm-next-2019-12-06' of git://anongit.freedesktop.org/drm/drm: (100 commits)
drm/dp_mst: Correct the bug in drm_dp_update_payload_part1()
drm/omap: fix dma_addr refcounting
drm/tegra: Run hub cleanup on ->remove()
drm/tegra: sor: Make the +5V HDMI supply optional
drm/tegra: Silence expected errors on IOMMU attach
drm/tegra: vic: Export module device table
drm/tegra: sor: Implement system suspend/resume
drm/tegra: Use proper IOVA address for cursor image
drm/tegra: gem: Remove premature import restrictions
drm/tegra: gem: Properly pin imported buffers
drm/tegra: hub: Remove bogus connection mutex check
ia64: agp: Replace empty define with do while
agp: Add bridge parameter documentation
agp: remove unused variable num_segments
agp: move AGPGART_MINOR to include/linux/miscdevice.h
agp: remove unused variable size in agp_generic_create_gatt_table
drm/dp_mst: Fix build on systems with STACKTRACE_SUPPORT=n
drm/radeon: fix r1xx/r2xx register checker for POT textures
drm/amdgpu: fix GFX10 missing CSIB set(v3)
drm/amdgpu: should stop GFX ring in hw_fini
...
When looking at SDEISR to determine the connection status of combo
outputs, we should use the phy index rather than the port index.
Although they're usually the same thing, EHL's DDI-D (port D) is
attached to PHY-A and SDEISR doesn't even have bits for a "D" output.
It's also possible that future platforms may map DDIs (the internal
display engine programming units) to PHYs (the output handling on the IO
side) in ways where port!=phy, so let's look at the PHY index by
default.
v2: Rename to intel_combo_phy_connected. (Lucas)
Fixes: 719d240026 ("drm/i915/ehl: Enable DDI-D")
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191127221314.575575-2-matthew.d.roper@intel.com
(cherry picked from commit 3d1e388d40)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Pull Kbuild updates from Masahiro Yamada:
- remove unneeded asm headers from hexagon, ia64
- add 'dir-pkg' target, which works like 'tar-pkg' but skips archiving
- add 'helpnewconfig' target, which shows help for new CONFIG options
- support 'make nsdeps' for external modules
- make rebuilds faster by deleting $(wildcard $^) checks
- remove compile tests for kernel-space headers
- refactor modpost to simplify modversion handling
- make single target builds faster
- optimize and clean up scripts/kallsyms.c
- refactor various Makefiles and scripts
* tag 'kbuild-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (59 commits)
MAINTAINERS: update Kbuild/Kconfig maintainer's email address
scripts/kallsyms: remove redundant initializers
scripts/kallsyms: put check_symbol_range() calls close together
scripts/kallsyms: make check_symbol_range() void function
scripts/kallsyms: move ignored symbol types to is_ignored_symbol()
scripts/kallsyms: move more patterns to the ignored_prefixes array
scripts/kallsyms: skip ignored symbols very early
scripts/kallsyms: add const qualifiers where possible
scripts/kallsyms: make find_token() return (unsigned char *)
scripts/kallsyms: replace prefix_underscores_count() with strspn()
scripts/kallsyms: add sym_name() to mitigate cast ugliness
scripts/kallsyms: remove unneeded length check for prefix matching
scripts/kallsyms: remove redundant is_arm_mapping_symbol()
scripts/kallsyms: set relative_base more effectively
scripts/kallsyms: shrink table before sorting it
scripts/kallsyms: fix definitely-lost memory leak
scripts/kallsyms: remove unneeded #ifndef ARRAY_SIZE
kbuild: make single target builds even faster
modpost: respect the previous export when 'exported twice' is warned
modpost: do not set ->preloaded for symbols from Module.symvers
...
Correct valid command length check for MI_ATOMIC, need to check inline
data available field instead of operand data length for whole command.
Fixes: 00a33be406 ("drm/i915/gvt: Add valid length check for MI variable commands")
Reported-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Gao Fred <fred.gao@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Pull drm updates from Dave Airlie:
"Lots of stuff in here, though it hasn't been too insane this merge
apart from dealing with the security fun.
uapi:
- export different colorspace properties on DP vs HDMI
- new fourcc for ARM 16x16 block format
- syncobj: allow querying last submitted timeline value
- DRM_FORMAT_BIG_ENDIAN defined as unsigned
core:
- allow using gem vma manager in ttm
- connector/encoder/bridge doc fixes
- allow more than 3 encoders for a connector
- displayport mst suspend/resume reprobing support
- vram lazy unmapping, uniform vram mm and gem vram
- edid cleanups + AVI informframe bar info
- displayport helpers - dpcd parser added
dp_cec:
- Allow a connector to be associated with a cec device
ttm:
- pipelining with no_gpu_wait fix
- always keep BOs on the LRU
sched:
- allow free_job routine to sleep
i915:
- Block userptr from mappable GTT
- i915 perf uapi versioning
- OA stream dynamic reconfiguration
- make context persistence optional
- introduce DRM_I915_UNSTABLE Kconfig
- add fake lmem testing under unstable
- BT.2020 support for DP MSA
- struct mutex elimination
- Tigerlake display/PLL/power management improvements
- Jasper Lake PCH support
- refactor PMU for multiple GPUs
- Icelake firmware update
- Split out vga + switcheroo code
amdgpu:
- implement dma-buf import/export without helpers
- vega20 RAS enablement
- DC i2c over aux fixes
- renoir GPU reset
- DC HDCP support
- BACO support for CI/VI asics
- MSI-X support
- Arcturus EEPROM support
- Arcturus VCN encode support
- VCN dynamic powergating on RV/RV2
amdkfd:
- add navi12/14/renoir support to kfd
radeon:
- SI dpm fix ported from amdgpu
- fix bad DMA on ppc platforms
gma500:
- memory leak fixes
qxl:
- convert to new gem mmap
exynos:
- build warning fix
komeda:
- add aclk sysfs attribute
v3d:
- userspace cleanup uapi change
i810:
- fix for underflow in dispatch ioctls
ast:
- refactor show_cursor
mgag200:
- refactor show_cursor
arcgpu:
- encoder finding improvements
mediatek:
- mipi_tx, dsi and partial crtc support for MT8183 SoC
- rotation support
meson:
- add suspend/resume support
omap:
- misc refactors
tegra:
- DisplayPort support for Tegra 210, 186 and 194.
- IOMMU-backed DMA API fixes
panfrost:
- fix lockdep issue
- simplify devfreq integration
rcar-du:
- R8A774B1 SoC support
- fixes for H2 ES2.0
sun4i:
- vcc-dsi regulator support
virtio-gpu:
- vmexit vs spinlock fix
- move to gem shmem helpers
- handle large command buffers with cma"
* tag 'drm-next-2019-11-27' of git://anongit.freedesktop.org/drm/drm: (1855 commits)
drm/amdgpu: invalidate mmhub semaphore workaround in gmc9/gmc10
drm/amdgpu: initialize vm_inv_eng0_sem for gfxhub and mmhub
drm/amd/amdgpu/sriov skip RLCG s/r list for arcturus VF.
drm/amd/amdgpu/sriov temporarily skip ras,dtm,hdcp for arcturus VF
drm/amdgpu/gfx10: re-init clear state buffer after gpu reset
merge fix for "ftrace: Rework event_create_dir()"
drm/amdgpu: Update Arcturus golden registers
drm/amdgpu/gfx10: fix out-of-bound mqd_backup array access
drm/amdgpu/gfx10: explicitly wait for cp idle after halt/unhalt
Revert "drm/amd/display: enable S/G for RAVEN chip"
drm/amdgpu: disable gfxoff on original raven
drm/amdgpu: remove experimental flag for Navi14
drm/amdgpu: disable gfxoff when using register read interface
drm/amdgpu/powerplay: properly set PP_GFXOFF_MASK (v2)
drm/amdgpu: fix bad DMA from INTERRUPT_CNTL2
drm/radeon: fix bad DMA from INTERRUPT_CNTL2
drm/amd/display: Fix debugfs on MST connectors
drm/amdgpu/nv: add asic func for fetching vbios from rom directly
drm/amdgpu: put flush_delayed_work at first
drm/amdgpu/vcn2.5: fix the enc loop with hw fini
...
The BitField of non privilege register address is only from bit 2 to 25.
v2: use REG_GENMASK instead. (Zhenyu)
Signed-off-by: Gao, Fred <fred.gao@intel.com>
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Pull locking updates from Ingo Molnar:
"The main changes in this cycle were:
- A comprehensive rewrite of the robust/PI futex code's exit handling
to fix various exit races. (Thomas Gleixner et al)
- Rework the generic REFCOUNT_FULL implementation using
atomic_fetch_* operations so that the performance impact of the
cmpxchg() loops is mitigated for common refcount operations.
With these performance improvements the generic implementation of
refcount_t should be good enough for everybody - and this got
confirmed by performance testing, so remove ARCH_HAS_REFCOUNT and
REFCOUNT_FULL entirely, leaving the generic implementation enabled
unconditionally. (Will Deacon)
- Other misc changes, fixes, cleanups"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
lkdtm: Remove references to CONFIG_REFCOUNT_FULL
locking/refcount: Remove unused 'refcount_error_report()' function
locking/refcount: Consolidate implementations of refcount_t
locking/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions
locking/refcount: Move saturation warnings out of line
locking/refcount: Improve performance of generic REFCOUNT_FULL code
locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the <linux/refcount.h> header
locking/refcount: Remove unused refcount_*_checked() variants
locking/refcount: Ensure integer operands are treated as signed
locking/refcount: Define constants for saturation and max refcount values
futex: Prevent exit livelock
futex: Provide distinct return value when owner is exiting
futex: Add mutex around futex exit
futex: Provide state handling for exec() as well
futex: Sanitize exit state handling
futex: Mark the begin of futex exit explicitly
futex: Set task::futex_state to DEAD right after handling futex exit
futex: Split futex_mm_release() for exit/exec
exit/exec: Seperate mm_release()
futex: Replace PF_EXITPIDONE with a state
...
Pull RCU updates from Ingo Molnar:
"The main changes in this cycle were:
- Dynamic tick (nohz) updates, perhaps most notably changes to force
the tick on when needed due to lengthy in-kernel execution on CPUs
on which RCU is waiting.
- Linux-kernel memory consistency model updates.
- Replace rcu_swap_protected() with rcu_prepace_pointer().
- Torture-test updates.
- Documentation updates.
- Miscellaneous fixes"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits)
security/safesetid: Replace rcu_swap_protected() with rcu_replace_pointer()
net/sched: Replace rcu_swap_protected() with rcu_replace_pointer()
net/netfilter: Replace rcu_swap_protected() with rcu_replace_pointer()
net/core: Replace rcu_swap_protected() with rcu_replace_pointer()
bpf/cgroup: Replace rcu_swap_protected() with rcu_replace_pointer()
fs/afs: Replace rcu_swap_protected() with rcu_replace_pointer()
drivers/scsi: Replace rcu_swap_protected() with rcu_replace_pointer()
drm/i915: Replace rcu_swap_protected() with rcu_replace_pointer()
x86/kvm/pmu: Replace rcu_swap_protected() with rcu_replace_pointer()
rcu: Upgrade rcu_swap_protected() to rcu_replace_pointer()
rcu: Suppress levelspread uninitialized messages
rcu: Fix uninitialized variable in nocb_gp_wait()
rcu: Update descriptions for rcu_future_grace_period tracepoint
rcu: Update descriptions for rcu_nocb_wake tracepoint
rcu: Remove obsolete descriptions for rcu_barrier tracepoint
rcu: Ensure that ->rcu_urgent_qs is set before resched IPI
workqueue: Convert for_each_wq to use built-in list check
rcu: Several rcu_segcblist functions can be static
rcu: Remove unused function hlist_bl_del_init_rcu()
Documentation: Rename rcu_node_context_switch() to rcu_note_context_switch()
...
In order to avoid some nasty mutex inversions, commit 09c5ab384f
("drm/i915: Keep rings pinned while the context is active") allowed the
intel_ring unpinning to be run concurrently with the next context
pinning it. Thus each step in intel_ring_unpin() needed to be atomic and
ordered in a nice onion with intel_ring_pin() so that the lifetimes
overlapped and were always safe.
Sadly, a few steps in intel_ring_unpin() were overlooked, such as
closing the read/write pointers of the ring and discarding the
intel_ring.vaddr, as these steps were not serialised with
intel_ring_pin() and so could leave the ring in disarray.
Fixes: 09c5ab384f ("drm/i915: Keep rings pinned while the context is active")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191118230254.2615942-6-chris@chris-wilson.co.uk
(cherry picked from commit a266bf4200)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
The major drawback of commit 7e34f4e4aa ("drm/i915/gen8+: Add RC6 CTX
corruption WA") is that it disables RC6 while Skylake (and friends) is
active, and we do not consider the GPU idle until all outstanding
requests have been retired and the engine switched over to the kernel
context. If userspace is idle, this task falls onto our background idle
worker, which only runs roughly once a second, meaning that userspace has
to have been idle for a couple of seconds before we enable RC6 again.
Naturally, this causes us to consume considerably more energy than
before as powersaving is effectively disabled while a display server
(here's looking at you Xorg) is running.
As execlists will get a completion event as each context is completed,
we can use this interrupt to queue a retire worker bound to this engine
to cleanup idle timelines. We will then immediately notice the idle
engine (without userspace intervention or the aid of the background
retire worker) and start parking the GPU. Thus during light workloads,
we will do much more work to idle the GPU faster... Hopefully with
commensurate power saving!
v2: Watch context completions and only look at those local to the engine
when retiring to reduce the amount of excess work we perform.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112315
References: 7e34f4e4aa ("drm/i915/gen8+: Add RC6 CTX corruption WA")
References: 2248a28384 ("drm/i915/gen8+: Add RC6 CTX corruption WA")
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/20191125105858.1718307-3-chris@chris-wilson.co.uk
(cherry picked from commit 4f88f8747f)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
In the next patch, we will introduce a new asynchronous retirement
worker, fed by execlists CS events. Here we may queue a retirement as
soon as a request is submitted to HW (and completes instantly), and we
also want to process that retirement as early as possible and cannot
afford to postpone (as there may not be another opportunity to retire it
for a few seconds). To allow the new async retirer to run in parallel
with our submission, pull the __i915_request_queue (that passes the
request to HW) inside the timelines spinlock so that the retirement
cannot release the timeline before we have completed the submission.
v2: Actually to play nicely with engine_retire, we have to raise the
timeline.active_lock before releasing the HW. intel_gt_retire_requsts()
is still serialised by the outer lock so they cannot see this
intermediate state, and engine_retire is serialised by HW submission.
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/20191125105858.1718307-2-chris@chris-wilson.co.uk
(cherry picked from commit 88a4655e75)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Since we want to do a lockless read of the current active request, and
that request is written to by process_csb also without serialisation, we
need to instruct gcc to take care in reading the pointer itself.
Otherwise, we have observed execlists_active() to report 0x40.
[ 2400.760381] igt/para-4098 1..s. 2376479300us : process_csb: rcs0 cs-irq head=3, tail=4
[ 2400.760826] igt/para-4098 1..s. 2376479303us : process_csb: rcs0 csb[4]: status=0x00000001:0x00000000
[ 2400.761271] igt/para-4098 1..s. 2376479306us : trace_ports: rcs0: promote { b9c59:2622, b9c55:2624 }
[ 2400.761726] igt/para-4097 0d... 2376479311us : __i915_schedule: rcs0: -2147483648->3, inflight:0000000000000040, rq:ffff888208c1e940
which is impossible!
The answer is that as we keep the existing execlists->active pointing
into the array as we copy over that array, the unserialised read may see
a partial pointer value.
Fixes: df40306902 ("drm/i915/execlists: Lift process_csb() out of the irq-off spinlock")
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/20191125094318.1630806-1-chris@chris-wilson.co.uk
(cherry picked from commit 331bf90591)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
In commit a79ca656b6 ("drm/i915: Push the wakeref->count deferral to
the backend"), I erroneously concluded that we last modify the engine
inside __i915_request_commit() meaning that we could enable concurrent
submission for userspace as we enqueued this request. However, this
falls into a trap with other users of the engine->kernel_context waking
up and submitting their request before the idle-switch is queued, with
the result that the kernel_context is executed out-of-sequence most
likely upsetting the GPU and certainly ourselves when we try to retire
the out-of-sequence requests.
As such we need to hold onto the effective engine->kernel_context mutex
lock (via the engine pm mutex proxy) until we have finish queuing the
request to the engine.
v2: Serialise against concurrent intel_gt_retire_requests()
v3: Describe the hairy locking scheme with intel_gt_retire_requests()
for future reference.
v4: Combine timeline->lock and engine pm release; it's hairy.
Fixes: a79ca656b6 ("drm/i915: Push the wakeref->count deferral to the backend")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191120165514.3955081-2-chris@chris-wilson.co.uk
(cherry picked from commit 5cba288466)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
The general concept was that intel_timeline.active_count was locked by
the intel_timeline.mutex. The exception was for power management, where
the engine->kernel_context->timeline could be manipulated under the
global wakeref.mutex.
This was quite solid, as we always manipulated the timeline only while
we held an engine wakeref.
And then we started retiring requests outside of struct_mutex, only
using the timelines.active_list and the timeline->mutex. There we
started manipulating intel_timeline.active_count outside of an engine
wakeref, and so introduced a race between __engine_park() and
intel_gt_retire_requests(), a race that could result in the
engine->kernel_context not being added to the active timelines and so
losing requests, which caused us to keep the system permanently powered
up [and unloadable].
The race would be easy to close if we could take the engine wakeref for
the timeline before we retire -- except timelines are not bound to any
engine and so we would need to keep all active engines awake. The
alternative is to guard intel_timeline_enter/intel_timeline_exit for use
outside of the timeline->mutex.
Fixes: e5dadff4b0 ("drm/i915: Protect request retirement with timeline->mutex")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191120165514.3955081-1-chris@chris-wilson.co.uk
(cherry picked from commit a6edbca74b)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
