Linaro-mm-sig

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8 participants
2915 discussions

Deploying new iterator interface for dma-buf

by Christian König

Next round for that one here, maybe the CI systems are now more gracefully with me :) I'm pretty sure that a couple of those dma_resv_for_each_fence_unlocked should actually be replaced with lock+dma_resv_for_each_fence, but that needs more auditing. Please review and comment. Thanks, Christian.

3 years, 9 months

Deploying new iterator interface for dma-buf

by Christian König

Hi everybody, we recently found that a good bunch of the RCU accesses to the dma_resv object are actually not correctly protected. Those where fixed by either dropping the RCU approach and taking appropriate locks or using a central function to return the current fences as array and then work with that snapshot. This set now tries to prevent adding any new broken code by rolling out two new interfaces to access the fences in a dma_resv object: dma_resv_for_each_fence() - Iterator which should be used while holding the reservation lock. dma_resv_for_each_fence_unlocked() - Iterator based on RCU which can be used without holding the reservation lock and automatic restart on concurrent modification. While doing this we also move the decision which fences to use for write and read accesses into the dma_resv object which results in a quite nice code de-duplication and simplification. The only two remaining users of the RCU shared fence interface are removing shared fences in amdkfd and debugfs code in qxl which will both be addresses in the next patch set. Please review and/or comment, Christian.

3 years, 9 months

Re: [Linaro-mm-sig] [PATCH v6 0/2] Add p2p via dmabuf to habanalabs

by Daniel Vetter

On Sun, Sep 12, 2021 at 07:53:07PM +0300, Oded Gabbay wrote: > Hi, > Re-sending this patch-set following the release of our user-space TPC > compiler and runtime library. > > I would appreciate a review on this. I think the big open we have is the entire revoke discussions. Having the option to let dma-buf hang around which map to random local memory ranges, without clear ownership link and a way to kill it sounds bad to me. I think there's a few options: - We require revoke support. But I've heard rdma really doesn't like that, I guess because taking out an MR while holding the dma_resv_lock would be an inversion, so can't be done. Jason, can you recap what exactly the hold-up was again that makes this a no-go? - The other option I discussed is a bit more the exlusive device ownership model we've had for gpus in drm of the really old kind. Roughly this would work like this, in terms of drm_device: - Only the current owner (drm_master in current drm code, but should probably rename that to drm_owner) is allowed to use the accel driver. So all ioctl would fail if you're not drm_master. - On dropmaster/file close we'd revoke as much as possible, e.g. in-flight commands, mmaps, anything really that can be revoked. - For non-revokable things like these dma-buf we'd keep a drm_master reference around. This would prevent the next open to acquire ownership rights, which at least prevents all the nasty potential problems. - admin (or well container orchestrator) then has responsibility to shoot down all process until the problem goes away (i.e. until you hit the one with the rdma MR which keeps the dma-buf alive) - Not sure there's another reasonable way to do this without inviting some problems once we get outside of the "single kernel instance per tenant" use-case. Wrt implementation there's the trouble of this reinventing a bunch of drm stuff and concepts, but that's maybe for after we've figured out semantics. Also would be great if you have a pull request for the userspace runtime that shows a bit how this all gets used and tied together. Or maybe some pointers, since I guess retconning a PR in github is maybe a bit much. Cheers, Daniel > > Thanks, > Oded > > Oded Gabbay (1): > habanalabs: define uAPI to export FD for DMA-BUF > > Tomer Tayar (1): > habanalabs: add support for dma-buf exporter > > drivers/misc/habanalabs/Kconfig | 1 + > drivers/misc/habanalabs/common/habanalabs.h | 22 + > drivers/misc/habanalabs/common/memory.c | 522 +++++++++++++++++++- > drivers/misc/habanalabs/gaudi/gaudi.c | 1 + > drivers/misc/habanalabs/goya/goya.c | 1 + > include/uapi/misc/habanalabs.h | 28 +- > 6 files changed, 570 insertions(+), 5 deletions(-) > > -- > 2.17.1 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch

3 years, 9 months

Re: [Linaro-mm-sig] [PATCH v3 0/9] dma-fence: Deadline awareness

by Rob Clark

On Thu, Sep 9, 2021 at 9:42 AM Simon Ser <contact(a)emersion.fr> wrote: > > On Thursday, September 9th, 2021 at 18:31, Rob Clark <robdclark(a)gmail.com> wrote: > > > Yes, I think it would.. and "dma-buf/sync_file: Add SET_DEADLINE > > ioctl" adds such an ioctl.. just for the benefit of igt tests at this > > point, but the thought was it would be also used by compositors that > > are doing such frame scheduling. Ofc danvet is a bit grumpy that > > there isn't a more real (than igt) userspace for the ioctl yet ;-) > > Ah, very nice, I somehow missed it. > > I guess one issue is that explicit sync isn't quite plumbed through > compositors yet, so without Jason's DMA-BUF to sync_file IOCTL it'd be > a bit difficult to use. > > Can anybody set the deadline? I wonder if clients should be allowed to. In its current form, anyone who has the fd can.. I'm not sure how (or even if) we could limit it beyond that. I suppose hypothetically you could use this for completely non-compositor related things, like compute jobs where you want the result by some deadline. (OTOH, it could be the driver using this internally when the app is stalling on a result) > What happens if the deadline is exceeded? I'd assume nothing in > particular, the deadline being just a hint? Nothing in particular, it is just a hint. The main intention is to provide a feedback hint to the drivers in scenarios like vblank deadlines, where being 1ms late is just as bad as being $frame_duration-1ms late. From my experiments and profiling it is useful in a couple scenarios: 1) input latency, ie. go from idle to fullscreen animation, where GPU has been idle for a while and not busy enough *yet* for devfreq to kick in and start ramping up the freq before we miss the first vblank 2) double buffering, for ex. if you are 1ms late you end up stalling 15ms before the gpu can start rendering the next frame.. in the absence of feedback, devfreq would ramp down in this scenario instead of up BR, -R

3 years, 9 months

Re: [Linaro-mm-sig] [PATCH v3 0/9] dma-fence: Deadline awareness

by Rob Clark

On Thu, Sep 9, 2021 at 9:16 AM Simon Ser <contact(a)emersion.fr> wrote: > > Out of curiosity, would it be reasonable to allow user-space (more > precisely, the compositor) to set the deadline via an IOCTL without > actually performing an atomic commit with the FB? > > Some compositors might want to wait themselves for FB fence completions > to ensure a client doesn't block the whole desktop (by submitting a > very costly rendering job). In this case it would make sense for the > compositor to indicate that it intends to display the buffer on next > vblank if it's ready by that point, without queueing a page-flip yet. Yes, I think it would.. and "dma-buf/sync_file: Add SET_DEADLINE ioctl" adds such an ioctl.. just for the benefit of igt tests at this point, but the thought was it would be also used by compositors that are doing such frame scheduling. Ofc danvet is a bit grumpy that there isn't a more real (than igt) userspace for the ioctl yet ;-) BR, -R

3 years, 9 months

[PATCH AUTOSEL 5.14 010/252] dma-buf: fix dma_resv_test_signaled test_all handling v2

by Sasha Levin

From: Christian König <christian.koenig(a)amd.com> [ Upstream commit 9d38814d1e346ea37a51cbf31f4424c9d059459e ] As the name implies if testing all fences is requested we should indeed test all fences and not skip the exclusive one because we see shared ones. v2: fix logic once more Signed-off-by: Christian König <christian.koenig(a)amd.com> Reviewed-by: Daniel Vetter <daniel.vetter(a)ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210702111642.17259-3-christ… Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- drivers/dma-buf/dma-resv.c | 33 ++++++++++++--------------------- 1 file changed, 12 insertions(+), 21 deletions(-) diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index f26c71747d43..e744fd87c63c 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -615,25 +615,21 @@ static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence) */ bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all) { - unsigned int seq, shared_count; + struct dma_fence *fence; + unsigned int seq; int ret; rcu_read_lock(); retry: ret = true; - shared_count = 0; seq = read_seqcount_begin(&obj->seq); if (test_all) { struct dma_resv_list *fobj = dma_resv_shared_list(obj); - unsigned int i; - - if (fobj) - shared_count = fobj->shared_count; + unsigned int i, shared_count; + shared_count = fobj ? fobj->shared_count : 0; for (i = 0; i < shared_count; ++i) { - struct dma_fence *fence; - fence = rcu_dereference(fobj->shared[i]); ret = dma_resv_test_signaled_single(fence); if (ret < 0) @@ -641,24 +637,19 @@ bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all) else if (!ret) break; } - - if (read_seqcount_retry(&obj->seq, seq)) - goto retry; } - if (!shared_count) { - struct dma_fence *fence_excl = dma_resv_excl_fence(obj); - - if (fence_excl) { - ret = dma_resv_test_signaled_single(fence_excl); - if (ret < 0) - goto retry; + fence = dma_resv_excl_fence(obj); + if (ret && fence) { + ret = dma_resv_test_signaled_single(fence); + if (ret < 0) + goto retry; - if (read_seqcount_retry(&obj->seq, seq)) - goto retry; - } } + if (read_seqcount_retry(&obj->seq, seq)) + goto retry; + rcu_read_unlock(); return ret; } -- 2.30.2

3 years, 10 months

[PATCH AUTOSEL 5.14 010/252] dma-buf: fix dma_resv_test_signaled test_all handling v2

by Sasha Levin

3 years, 10 months

Harden the dma-fence documentation a bit more

by Christian König

Hi guys, while it is in most cases technically possible to not have a reference to the dma_fence when adding a callback it is usually a good idea to make sure to always have a reference anyway. Otherwise we can indeed see cases where this doesn't really work as intended like for example in the now fixed EPOLL code. Regards, Christian.

3 years, 10 months

Re: [Linaro-mm-sig] [PATCH] dma-buf: Add support for mapping buffers with DMA attributes

by Daniel Vetter

On Mon, Aug 30, 2021 at 10:39:11AM +0800, guangming.cao(a)mediatek.com wrote: > From: Guangming Cao <Guangming.Cao(a)mediatek.com> > > When mapping the memory represented by a dma-buf into a device's > address space, it might be desireable to map the memory with > certain DMA attributes. Thus, introduce the dma_mapping_attrs > field in the dma_buf_attachment structure so that when > the memory is mapped with dma_buf_map_attachment, it is mapped > with the desired DMA attributes. > > Signed-off-by: Isaac J. Manjarres <isaacm(a)codeaurora.org> > Signed-off-by: Sandeep Patil <sspatil(a)google.com> > Signed-off-by: Guangming Cao <Guangming.Cao(a)mediatek.com> Can you pls include the code that's going to use this here too? At a glance all the attributes you might want to set are supposed to be under the control of the exporter, not the importer. -Daniel > --- > drivers/dma-buf/heaps/cma_heap.c | 6 ++++-- > drivers/dma-buf/heaps/system_heap.c | 6 ++++-- > include/linux/dma-buf.h | 3 +++ > 3 files changed, 11 insertions(+), 4 deletions(-) > > diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c > index 0c05b79870f9..2c9feb3bfc3e 100644 > --- a/drivers/dma-buf/heaps/cma_heap.c > +++ b/drivers/dma-buf/heaps/cma_heap.c > @@ -99,9 +99,10 @@ static struct sg_table *cma_heap_map_dma_buf(struct dma_buf_attachment *attachme > { > struct dma_heap_attachment *a = attachment->priv; > struct sg_table *table = &a->table; > + int attrs = attachment->dma_map_attrs; > int ret; > > - ret = dma_map_sgtable(attachment->dev, table, direction, 0); > + ret = dma_map_sgtable(attachment->dev, table, direction, attrs); > if (ret) > return ERR_PTR(-ENOMEM); > a->mapped = true; > @@ -113,9 +114,10 @@ static void cma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, > enum dma_data_direction direction) > { > struct dma_heap_attachment *a = attachment->priv; > + int attrs = attachment->dma_map_attrs; > > a->mapped = false; > - dma_unmap_sgtable(attachment->dev, table, direction, 0); > + dma_unmap_sgtable(attachment->dev, table, direction, attrs); > } > > static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, > diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c > index 23a7e74ef966..fc7b1e02988e 100644 > --- a/drivers/dma-buf/heaps/system_heap.c > +++ b/drivers/dma-buf/heaps/system_heap.c > @@ -130,9 +130,10 @@ static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attac > { > struct dma_heap_attachment *a = attachment->priv; > struct sg_table *table = a->table; > + int attrs = attachment->dma_map_attrs; > int ret; > > - ret = dma_map_sgtable(attachment->dev, table, direction, 0); > + ret = dma_map_sgtable(attachment->dev, table, direction, attrs); > if (ret) > return ERR_PTR(ret); > > @@ -145,9 +146,10 @@ static void system_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, > enum dma_data_direction direction) > { > struct dma_heap_attachment *a = attachment->priv; > + int attrs = attachment->dma_map_attrs; > > a->mapped = false; > - dma_unmap_sgtable(attachment->dev, table, direction, 0); > + dma_unmap_sgtable(attachment->dev, table, direction, attrs); > } > > static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h > index efdc56b9d95f..4d650731766e 100644 > --- a/include/linux/dma-buf.h > +++ b/include/linux/dma-buf.h > @@ -379,6 +379,8 @@ struct dma_buf_attach_ops { > * @importer_ops: importer operations for this attachment, if provided > * dma_buf_map/unmap_attachment() must be called with the dma_resv lock held. > * @importer_priv: importer specific attachment data. > + * @dma_map_attrs: DMA attributes to be used when the exporter maps the buffer > + * through dma_buf_map_attachment. > * > * This structure holds the attachment information between the dma_buf buffer > * and its user device(s). The list contains one attachment struct per device > @@ -399,6 +401,7 @@ struct dma_buf_attachment { > const struct dma_buf_attach_ops *importer_ops; > void *importer_priv; > void *priv; > + unsigned long dma_map_attrs; > }; > > /** > -- > 2.17.1 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch

3 years, 10 months

[PATCH 1/2] dma-buf: nuke DMA_FENCE_TRACE macros v2

by Christian König

Only the DRM GPU scheduler, radeon and amdgpu where using them and they depend on a non existing config option to actually emit some code. v2: keep the signal path as is for now Signed-off-by: Christian König <christian.koenig(a)amd.com> --- drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 10 +--------- drivers/gpu/drm/radeon/radeon_fence.c | 24 ++++------------------- drivers/gpu/drm/scheduler/sched_fence.c | 18 ++--------------- include/linux/dma-fence.h | 22 --------------------- 4 files changed, 7 insertions(+), 67 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c index 0b1c48590c43..c65994e382bd 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c @@ -246,7 +246,6 @@ bool amdgpu_fence_process(struct amdgpu_ring *ring) struct amdgpu_fence_driver *drv = &ring->fence_drv; struct amdgpu_device *adev = ring->adev; uint32_t seq, last_seq; - int r; do { last_seq = atomic_read(&ring->fence_drv.last_seq); @@ -278,12 +277,7 @@ bool amdgpu_fence_process(struct amdgpu_ring *ring) if (!fence) continue; - r = dma_fence_signal(fence); - if (!r) - DMA_FENCE_TRACE(fence, "signaled from irq context\n"); - else - BUG(); - + dma_fence_signal(fence); dma_fence_put(fence); pm_runtime_mark_last_busy(adev_to_drm(adev)->dev); pm_runtime_put_autosuspend(adev_to_drm(adev)->dev); @@ -639,8 +633,6 @@ static bool amdgpu_fence_enable_signaling(struct dma_fence *f) if (!timer_pending(&ring->fence_drv.fallback_timer)) amdgpu_fence_schedule_fallback(ring); - DMA_FENCE_TRACE(&fence->base, "armed on ring %i!\n", ring->idx); - return true; } diff --git a/drivers/gpu/drm/radeon/radeon_fence.c b/drivers/gpu/drm/radeon/radeon_fence.c index 18f2c2e0dfb3..3f351d222cbb 100644 --- a/drivers/gpu/drm/radeon/radeon_fence.c +++ b/drivers/gpu/drm/radeon/radeon_fence.c @@ -176,18 +176,11 @@ static int radeon_fence_check_signaled(wait_queue_entry_t *wait, unsigned mode, */ seq = atomic64_read(&fence->rdev->fence_drv[fence->ring].last_seq); if (seq >= fence->seq) { - int ret = dma_fence_signal_locked(&fence->base); - - if (!ret) - DMA_FENCE_TRACE(&fence->base, "signaled from irq context\n"); - else - DMA_FENCE_TRACE(&fence->base, "was already signaled\n"); - + dma_fence_signal_locked(&fence->base); radeon_irq_kms_sw_irq_put(fence->rdev, fence->ring); __remove_wait_queue(&fence->rdev->fence_queue, &fence->fence_wake); dma_fence_put(&fence->base); - } else - DMA_FENCE_TRACE(&fence->base, "pending\n"); + } return 0; } @@ -422,8 +415,6 @@ static bool radeon_fence_enable_signaling(struct dma_fence *f) fence->fence_wake.func = radeon_fence_check_signaled; __add_wait_queue(&rdev->fence_queue, &fence->fence_wake); dma_fence_get(f); - - DMA_FENCE_TRACE(&fence->base, "armed on ring %i!\n", fence->ring); return true; } @@ -441,11 +432,7 @@ bool radeon_fence_signaled(struct radeon_fence *fence) return true; if (radeon_fence_seq_signaled(fence->rdev, fence->seq, fence->ring)) { - int ret; - - ret = dma_fence_signal(&fence->base); - if (!ret) - DMA_FENCE_TRACE(&fence->base, "signaled from radeon_fence_signaled\n"); + dma_fence_signal(&fence->base); return true; } return false; @@ -550,7 +537,6 @@ long radeon_fence_wait_timeout(struct radeon_fence *fence, bool intr, long timeo { uint64_t seq[RADEON_NUM_RINGS] = {}; long r; - int r_sig; /* * This function should not be called on !radeon fences. @@ -567,9 +553,7 @@ long radeon_fence_wait_timeout(struct radeon_fence *fence, bool intr, long timeo return r; } - r_sig = dma_fence_signal(&fence->base); - if (!r_sig) - DMA_FENCE_TRACE(&fence->base, "signaled from fence_wait\n"); + dma_fence_signal(&fence->base); return r; } diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c index 69de2c76731f..3736746c47bd 100644 --- a/drivers/gpu/drm/scheduler/sched_fence.c +++ b/drivers/gpu/drm/scheduler/sched_fence.c @@ -50,26 +50,12 @@ static void __exit drm_sched_fence_slab_fini(void) void drm_sched_fence_scheduled(struct drm_sched_fence *fence) { - int ret = dma_fence_signal(&fence->scheduled); - - if (!ret) - DMA_FENCE_TRACE(&fence->scheduled, - "signaled from irq context\n"); - else - DMA_FENCE_TRACE(&fence->scheduled, - "was already signaled\n"); + dma_fence_signal(&fence->scheduled); } void drm_sched_fence_finished(struct drm_sched_fence *fence) { - int ret = dma_fence_signal(&fence->finished); - - if (!ret) - DMA_FENCE_TRACE(&fence->finished, - "signaled from irq context\n"); - else - DMA_FENCE_TRACE(&fence->finished, - "was already signaled\n"); + dma_fence_signal(&fence->finished); } static const char *drm_sched_fence_get_driver_name(struct dma_fence *fence) diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 6ffb4b2c6371..4cc119ab272f 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -590,26 +590,4 @@ struct dma_fence *dma_fence_get_stub(void); struct dma_fence *dma_fence_allocate_private_stub(void); u64 dma_fence_context_alloc(unsigned num); -#define DMA_FENCE_TRACE(f, fmt, args...) \ - do { \ - struct dma_fence *__ff = (f); \ - if (IS_ENABLED(CONFIG_DMA_FENCE_TRACE)) \ - pr_info("f %llu#%llu: " fmt, \ - __ff->context, __ff->seqno, ##args); \ - } while (0) - -#define DMA_FENCE_WARN(f, fmt, args...) \ - do { \ - struct dma_fence *__ff = (f); \ - pr_warn("f %llu#%llu: " fmt, __ff->context, __ff->seqno,\ - ##args); \ - } while (0) - -#define DMA_FENCE_ERR(f, fmt, args...) \ - do { \ - struct dma_fence *__ff = (f); \ - pr_err("f %llu#%llu: " fmt, __ff->context, __ff->seqno, \ - ##args); \ - } while (0) - #endif /* __LINUX_DMA_FENCE_H */ -- 2.25.1

3 years, 10 months

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