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Semnatically it really doesn't matter where we grab the ticket. But
since the ticket is a fake lockdep lock, it matters for lockdep
validation purposes.
This means stuff like grabbing a ticket and then doing
copy_from/to_user isn't allowed anymore. This is a changed compared to
the current ttm fault handler, which doesn't bother with having a full
reservation. Since I'm looking into fixing the TODO entry in
ttm_mem_evict_wait_busy() I think that'll have to change sooner or
later anyway, better get started. A bit more context on why I'm
looking into this: For backwards compat with existing i915 gem code I
think we'll have to do full slowpath locking in the i915 equivalent of
the eviction code. And with dynamic dma-buf that will leak across
drivers, so another thing we need to standardize and make sure it's
done the same way everyway.
Unfortunately this means another full audit of all drivers:
- gem helpers: acquire_init is done right before taking locks, so no
problem. Same for acquire_fini and unlocking, which means nothing
that's not already covered by the dma_resv_lock rules will be caught
with this extension here to the acquire_ctx.
- etnaviv: An absolute massive amount of code is run between the
acquire_init and the first lock acquisition in submit_lock_objects.
But nothing that would touch user memory and could cause a fault.
Furthermore nothing that uses the ticket, so even if I missed
something, it would be easy to fix by pushing the acquire_init right
before the first use. Similar on the unlock/acquire_fini side.
- i915: Right now (and this will likely change a lot rsn) the acquire
ctx and actual locks are right next to each another. No problem.
- msm has a problem: submit_create calls acquire_init, but then
submit_lookup_objects() has a bunch of copy_from_user to do the
object lookups. That's the only thing before submit_lock_objects
call dma_resv_lock(). Despite all the copypasta to etnaviv, etnaviv
does not have this issue since it copies all the userspace structs
earlier. submit_cleanup does not have any such issues.
With the prep patch to pull out the acquire_ctx and reorder it msm
is going to be safe too.
- nouveau: acquire_init is right next to ttm_bo_reserve, so all good.
Similar on the acquire_fini/ttm_bo_unreserve side.
- ttm execbuf utils: acquire context and locking are even in the same
functions here (one function to reserve everything, the other to
unreserve), so all good.
- vc4: Another case where acquire context and locking are handled in
the same functions (one function to lock everything, the other to
unlock).
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christian König <christian.koenig@amd.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: Huang Rui <ray.huang@amd.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Russell King <linux+etnaviv@armlinux.org.uk>
Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <sean@poorly.run>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191119210844.16947-3-daniel.vetter@ffwll.ch
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From d07ea81611ed6e4fb8cc290f42d23dbcca2da2f8 Mon Sep 17 00:00:00 2001
From: Steven Price <steven.price@arm.com>
Date: Mon, 11 Nov 2019 13:07:19 +0000
Subject: [PATCH] dma_resv: Correct return type of dma_resv_lockdep()
subsys_initcall() expects a function which returns 'int'. Fix
dma_resv_lockdep() so it returns an 'int' error code.
Fixes: b2a8116e2592 ("dma_resv: prime lockdep annotations")
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/c0a0c70d-e6fe-1103-2888-1ce1425f4a5d@arm.com
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Full audit of everyone:
- i915, radeon, amdgpu should be clean per their maintainers.
- vram helpers should be fine, they don't do command submission, so
really no business holding struct_mutex while doing copy_*_user. But
I haven't checked them all.
- panfrost seems to dma_resv_lock only in panfrost_job_push, which
looks clean.
- v3d holds dma_resv locks in the tail of its v3d_submit_cl_ioctl(),
copying from/to userspace happens all in v3d_lookup_bos which is
outside of the critical section.
- vmwgfx has a bunch of ioctls that do their own copy_*_user:
- vmw_execbuf_process: First this does some copies in
vmw_execbuf_cmdbuf() and also in the vmw_execbuf_process() itself.
Then comes the usual ttm reserve/validate sequence, then actual
submission/fencing, then unreserving, and finally some more
copy_to_user in vmw_execbuf_copy_fence_user. Glossing over tons of
details, but looks all safe.
- vmw_fence_event_ioctl: No ttm_reserve/dma_resv_lock anywhere to be
seen, seems to only create a fence and copy it out.
- a pile of smaller ioctl in vmwgfx_ioctl.c, no reservations to be
found there.
Summary: vmwgfx seems to be fine too.
- virtio: There's virtio_gpu_execbuffer_ioctl, which does all the
copying from userspace before even looking up objects through their
handles, so safe. Plus the getparam/getcaps ioctl, also both safe.
- qxl only has qxl_execbuffer_ioctl, which calls into
qxl_process_single_command. There's a lovely comment before the
__copy_from_user_inatomic that the slowpath should be copied from
i915, but I guess that never happened. Try not to be unlucky and get
your CS data evicted between when it's written and the kernel tries
to read it. The only other copy_from_user is for relocs, but those
are done before qxl_release_reserve_list(), which seems to be the
only thing reserving buffers (in the ttm/dma_resv sense) in that
code. So looks safe.
- A debugfs file in nouveau_debugfs_pstate_set() and the usif ioctl in
usif_ioctl() look safe. nouveau_gem_ioctl_pushbuf() otoh breaks this
everywhere and needs to be fixed up.
v2: Thomas pointed at that vmwgfx calls dma_resv_init while it holds a
dma_resv lock of a different object already. Christian mentioned that
ttm core does this too for ghost objects. intel-gfx-ci highlighted
that i915 has similar issues.
Unfortunately we can't do this in the usual module init functions,
because kernel threads don't have an ->mm - we have to wait around for
some user thread to do this.
Solution is to spawn a worker (but only once). It's horrible, but it
works.
v3: We can allocate mm! (Chris). Horrible worker hack out, clean
initcall solution in.
v4: Annotate with __init (Rob Herring)
Cc: Rob Herring <robh@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: "VMware Graphics" <linux-graphics-maintainer@vmware.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191104173801.2972-1-daniel.vetter@ffwll.ch
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This causes kernel crash when testing lima driver.
Cc: Christian König <christian.koenig@amd.com>
Fixes: b8c036dfc66f ("dma-buf: simplify reservation_object_get_fences_rcu a bit")
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190922074900.853-1-yuq825@gmail.com
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This reverts
67c97fb79a7f ("dma-buf: add reservation_object_fences helper")
dd7a7d1ff2f1 ("drm/i915: use new reservation_object_fences helper")
0e1d8083bddb ("dma-buf: further relax reservation_object_add_shared_fence")
5d344f58da76 ("dma-buf: nuke reservation_object seq number")
The scenario that defeats simply grabbing a set of shared/exclusive
fences and using them blissfully under RCU is that any of those fences
may be reallocated by a SLAB_TYPESAFE_BY_RCU fence slab cache. In this
scenario, while keeping the rcu_read_lock we need to establish that no
fence was changed in the dma_resv after a read (or full) memory barrier.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190814182401.25009-1-chris@chris-wilson.co.uk
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Be more consistent with the naming of the other DMA-buf objects.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/323401/
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Daniel Vetter
Steven Price
Qiang Yu
Chris Wilson
Christian König