kernel/drivers/gpu/drm/i915/i915_gem.c, branch linux-4.4.y

drm/i915: Flush TLBs before releasing backing store

2022-01-29T09:14:33Z

commit 7938d61591d33394a21bdd7797a245b65428f44c upstream. We need to flush TLBs before releasing backing store otherwise userspace is able to encounter stale entries if a) it is not declaring access to certain buffers and b) it races with the backing store release from a such undeclared execution already executing on the GPU in parallel. The approach taken is to mark any buffer objects which were ever bound to the GPU and to trigger a serialized TLB flush when their backing store is released. Alternatively the flushing could be done on VMA unbind, at which point we would be able to ascertain whether there is potential a parallel GPU execution (which could race), but essentially it boils down to paying the cost of TLB flushes potentially needlessly at VMA unbind time (when the backing store is not known to be going away so not needed for safety), versus potentially needlessly at backing store relase time (since we at that point cannot tell whether there is anything executing on the GPU which uses that object). Thereforce simplicity of implementation has been chosen for now with scope to benchmark and refine later as required. Signed-off-by: Tvrtko Ursulin Reported-by: Sushma Venkatesh Reddy Reviewed-by: Daniel Vetter Acked-by: Dave Airlie Cc: Daniel Vetter Cc: Jon Bloomfield Cc: Joonas Lahtinen Cc: Jani Nikula Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

drm/i915: Only spin whilst waiting on the current request

2015-12-22T10:56:58Z

Limit busywaiting only to the request currently being processed by the GPU. If the request is not currently being processed by the GPU, there is a very low likelihood of it being completed within the 2 microsecond spin timeout and so we will just be wasting CPU cycles. v2: Check for logical inversion when rebasing - we were incorrectly checking for this request being active, and instead busywaiting for when the GPU was not yet processing the request of interest. v3: Try another colour for the seqno names. v4: Another colour for the function names. v5: Remove the forced coherency when checking for the active request. On reflection and plenty of recent experimentation, the issue is not a cache coherency problem - but an irq/seqno ordering problem (timing issue). Here, we do not need the w/a to force ordering of the read with an interrupt. Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin Cc: "Rogozhkin, Dmitry V" Cc: Daniel Vetter Cc: Tvrtko Ursulin Cc: Eero Tamminen Cc: "Rantala, Valtteri" Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1449833608-22125-4-git-send-email-chris@chris-wilson.co.uk (cherry picked from commit 821485dc2ad665f136c57ee589bf7a8210160fe2) Signed-off-by: Jani Nikula

drm/i915: Limit the busy wait on requests to 5us not 10ms!

2015-12-22T10:55:50Z

When waiting for high frequency requests, the finite amount of time required to set up the irq and wait upon it limits the response rate. By busywaiting on the request completion for a short while we can service the high frequency waits as quick as possible. However, if it is a slow request, we want to sleep as quickly as possible. The tradeoff between waiting and sleeping is roughly the time it takes to sleep on a request, on the order of a microsecond. Based on measurements of synchronous workloads from across big core and little atom, I have set the limit for busywaiting as 10 microseconds. In most of the synchronous cases, we can reduce the limit down to as little as 2 miscroseconds, but that leaves quite a few test cases regressing by factors of 3 and more. The code currently uses the jiffie clock, but that is far too coarse (on the order of 10 milliseconds) and results in poor interactivity as the CPU ends up being hogged by slow requests. To get microsecond resolution we need to use a high resolution timer. The cheapest of which is polling local_clock(), but that is only valid on the same CPU. If we switch CPUs because the task was preempted, we can also use that as an indicator that the system is too busy to waste cycles on spinning and we should sleep instead. __i915_spin_request was introduced in commit 2def4ad99befa25775dd2f714fdd4d92faec6e34 [v4.2] Author: Chris Wilson Date: Tue Apr 7 16:20:41 2015 +0100 drm/i915: Optimistically spin for the request completion v2: Drop full u64 for unsigned long - the timer is 32bit wraparound safe, so we can use native register sizes on smaller architectures. Mention the approximate microseconds units for elapsed time and add some extra comments describing the reason for busywaiting. v3: Raise the limit to 10us v4: Now 5us. Reported-by: Jens Axboe Link: https://lkml.org/lkml/2015/11/12/621 Reviewed-by: Tvrtko Ursulin Cc: "Rogozhkin, Dmitry V" Cc: Daniel Vetter Cc: Tvrtko Ursulin Cc: Eero Tamminen Cc: "Rantala, Valtteri" Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1449833608-22125-3-git-send-email-chris@chris-wilson.co.uk (cherry picked from commit ca5b721e238226af1d767103ac852aeb8e4c0764) Signed-off-by: Jani Nikula

drm/i915: Break busywaiting for requests on pending signals

2015-12-22T10:55:01Z

The busywait in __i915_spin_request() does not respect pending signals and so may consume the entire timeslice for the task instead of returning to userspace to handle the signal. In the worst case this could cause a delay in signal processing of 20ms, which would be a noticeable jitter in cursor tracking. If a higher resolution signal was being used, for example to provide fairness of a server timeslices between clients, we could expect to detect some unfairness between clients (i.e. some windows not updating as fast as others). This issue was noticed when inspecting a report of poor interactivity resulting from excessively high __i915_spin_request usage. Fixes regression from commit 2def4ad99befa25775dd2f714fdd4d92faec6e34 [v4.2] Author: Chris Wilson Date: Tue Apr 7 16:20:41 2015 +0100 drm/i915: Optimistically spin for the request completion v2: Try to assess the impact of the bug Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin Cc: Jens Axboe Cc; "Rogozhkin, Dmitry V" Cc: Daniel Vetter Cc: Tvrtko Ursulin Cc: Eero Tamminen Cc: "Rantala, Valtteri" Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1449833608-22125-2-git-send-email-chris@chris-wilson.co.uk (cherry picked from commit 91b0c352ace9afec1fb51590c7b8bd60e0eb9fbd) Signed-off-by: Jani Nikula

drm/i915: Set the map-and-fenceable flag for preallocated objects

2015-12-22T09:52:27Z

As we mark the preallocated objects as bound, we should also flag them correctly as being map-and-fenceable (if appropriate!) so that later users do not get confused and try and rebind the pinned vma in order to get a map-and-fenceable binding. Signed-off-by: Chris Wilson Cc: "Goel, Akash" Cc: Daniel Vetter Cc: Jesse Barnes Cc: drm-intel-fixes@lists.freedesktop.org Link: http://patchwork.freedesktop.org/patch/msgid/1448029000-10616-1-git-send-email-chris@chris-wilson.co.uk Reviewed-by: Jesse Barnes Signed-off-by: Daniel Vetter (cherry picked from commit d0710abbcd88b1ff17760e97d74a673e67b49ea1) Signed-off-by: Jani Nikula

drm/i915: Check the timeout passed to i915_wait_request

2015-12-01T08:48:58Z

We have relied upon the sole caller (wait_ioctl) validating the timeout argument. However, when waiting for multiple requests I forgot to ensure that the timeout was still positive on the later requests. This is more simply done inside __i915_wait_request. Fixes regression introduced in commit b47161858ba13c9c7e03333132230d66e008dd55 Author: Chris Wilson Date: Mon Apr 27 13:41:17 2015 +0100 drm/i915: Implement inter-engine read-read optimisations The impact of the regression is 1 jiffie for each extra active ring for a wait_ioctl with a timeout -- I don't think anyone has noticed. Signed-off-by: Chris Wilson Cc: Lionel Landwerlin Cc: Tvrtko Ursulin Cc: Daniel Vetter Reviewed-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1448544702-5594-1-git-send-email-chris@chris-wilson.co.uk Signed-off-by: Jani Nikula

drm/i915: get runtime PM reference around GEM set_caching IOCTL

2015-11-16T13:32:08Z

After Damien's D3 fix I started to get runtime suspend residency for the first time and that revealed a breakage on the set_caching IOCTL path that accesses the HW but doesn't take an RPM ref. Fix this up. Signed-off-by: Imre Deak Reviewed-by: Paulo Zanoni Cc: stable@vger.kernel.org Link: http://patchwork.freedesktop.org/patch/msgid/1446665132-22491-1-git-send-email-imre.deak@intel.com Signed-off-by: Jani Nikula

Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux

2015-11-10T17:33:06Z

Pull drm updates from Dave Airlie: "I Was Almost Tempted To Capitalise Every Word, but then I decided I couldn't read it myself! I've also got one pull request for the sti driver outstanding. It relied on a commit in Greg's tree and I didn't find out in time, that commit is in your tree now so I might send that along once this is merged. I also had the accidental misfortune to have access to a Skylake on my desk for a few days, and I've had to encourage Intel to try harder, which seems to be happening now. Here is the main drm-next pull request for 4.4. Highlights: New driver: vc4 driver for the Rasberry Pi VPU. (From Eric Anholt at Broadcom.) Core: Atomic fbdev support Atomic helpers for runtime pm dp/aux i2c STATUS_UPDATE handling struct_mutex usage cleanups. Generic of probing support. Documentation: Kerneldoc for VGA switcheroo code. Rename to gpu instead of drm to reflect scope. i915: Skylake GuC firmware fixes HPD A support VBT backlight fallbacks Fastboot by default for some systems FBC work BXT/SKL workarounds Skylake deeper sleep state fixes amdgpu: Enable GPU scheduler by default New atombios opcodes GPUVM debugging options Stoney support. Fencing cleanups. radeon: More efficient CS checking nouveau: gk20a instance memory handling improvements. Improved PGOB detection and GK107 support Kepler GDDR5 PLL statbility improvement G8x/GT2xx reclock improvements new userspace API compatiblity fixes. virtio-gpu: Add 3D support - qemu 2.5 has it merged for it's gtk backend. msm: Initial msm88896 (snapdragon 8200) exynos: HDMI cleanups Enable mixer driver byt default Add DECON-TV support vmwgfx: Move to using memremap + fixes. rcar-du: Add support for R8A7793/4 DU armada: Remove support for non-component mode Improved plane handling Power savings while in DPMS off. tda998x: Remove unused slave encoder support Use more HDMI helpers Fix EDID read handling dwhdmi: Interlace video mode support for ipu-v3/dw_hdmi Hotplug state fixes Audio driver integration imx: More color formats support. tegra: Minor fixes/improvements" [ Merge fixup: remove unused variable 'dev' that had all uses removed in commit 4e270f088011: "drm/gem: Drop struct_mutex requirement from drm_gem_mmap_obj" ] * 'drm-next' of git://people.freedesktop.org/~airlied/linux: (764 commits) drm/vmwgfx: Relax irq locking somewhat drm/vmwgfx: Properly flush cursor updates and page-flips drm/i915/skl: disable display side power well support for now drm/i915: Extend DSL readout fix to BDW and SKL. drm/i915: Do graphics device reset under forcewake drm/i915: Skip fence installation for objects with rotated views (v4) vga_switcheroo: Drop client power state VGA_SWITCHEROO_INIT drm/amdgpu: group together common fence implementation drm/amdgpu: remove AMDGPU_FENCE_OWNER_MOVE drm/amdgpu: remove now unused fence functions drm/amdgpu: fix fence fallback check drm/amdgpu: fix stoping the scheduler timeout drm/amdgpu: cleanup on error in amdgpu_cs_ioctl() drm/i915: Fix locking around GuC firmware load drm/amdgpu: update Fiji's Golden setting drm/amdgpu: update Fiji's rev id drm/amdgpu: extract common code in vi_common_early_init drm/amd/scheduler: don't oops on failure to load drm/amdgpu: don't oops on failure to load (v2) drm/amdgpu: don't VT switch on suspend ...

mm, fs: introduce mapping_gfp_constraint()

2015-11-07T01:50:42Z

There are many places which use mapping_gfp_mask to restrict a more generic gfp mask which would be used for allocations which are not directly related to the page cache but they are performed in the same context. Let's introduce a helper function which makes the restriction explicit and easier to track. This patch doesn't introduce any functional changes. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Michal Hocko Suggested-by: Andrew Morton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM

2015-11-07T01:50:42Z

__GFP_WAIT was used to signal that the caller was in atomic context and could not sleep. Now it is possible to distinguish between true atomic context and callers that are not willing to sleep. The latter should clear __GFP_DIRECT_RECLAIM so kswapd will still wake. As clearing __GFP_WAIT behaves differently, there is a risk that people will clear the wrong flags. This patch renames __GFP_WAIT to __GFP_RECLAIM to clearly indicate what it does -- setting it allows all reclaim activity, clearing them prevents it. [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Mel Gorman Acked-by: Michal Hocko Acked-by: Vlastimil Babka Acked-by: Johannes Weiner Cc: Christoph Lameter Acked-by: David Rientjes Cc: Vitaly Wool Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds