Linaro-mm-sig

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3030 discussions

[PATCH] dma-buf: system_heap: No separate allocation for attachment sg_tables

by T.J. Mercier

struct dma_heap_attachment is a separate allocation from the struct sg_table it contains, but there is no reason for this. Let's use the slab allocator just once instead of twice for dma_heap_attachment. Signed-off-by: T.J. Mercier <tjmercier(a)google.com> --- drivers/dma-buf/heaps/system_heap.c | 43 ++++++++++++----------------- 1 file changed, 17 insertions(+), 26 deletions(-) diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index 26d5dc89ea16..bee10c400cf0 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -35,7 +35,7 @@ struct system_heap_buffer { struct dma_heap_attachment { struct device *dev; - struct sg_table *table; + struct sg_table table; struct list_head list; bool mapped; }; @@ -54,29 +54,22 @@ static gfp_t order_flags[] = {HIGH_ORDER_GFP, HIGH_ORDER_GFP, LOW_ORDER_GFP}; static const unsigned int orders[] = {8, 4, 0}; #define NUM_ORDERS ARRAY_SIZE(orders) -static struct sg_table *dup_sg_table(struct sg_table *table) +static int dup_sg_table(struct sg_table *from, struct sg_table *to) { - struct sg_table *new_table; - int ret, i; struct scatterlist *sg, *new_sg; + int ret, i; - new_table = kzalloc(sizeof(*new_table), GFP_KERNEL); - if (!new_table) - return ERR_PTR(-ENOMEM); - - ret = sg_alloc_table(new_table, table->orig_nents, GFP_KERNEL); - if (ret) { - kfree(new_table); - return ERR_PTR(-ENOMEM); - } + ret = sg_alloc_table(to, from->orig_nents, GFP_KERNEL); + if (ret) + return ret; - new_sg = new_table->sgl; - for_each_sgtable_sg(table, sg, i) { + new_sg = to->sgl; + for_each_sgtable_sg(from, sg, i) { sg_set_page(new_sg, sg_page(sg), sg->length, sg->offset); new_sg = sg_next(new_sg); } - return new_table; + return 0; } static int system_heap_attach(struct dma_buf *dmabuf, @@ -84,19 +77,18 @@ static int system_heap_attach(struct dma_buf *dmabuf, { struct system_heap_buffer *buffer = dmabuf->priv; struct dma_heap_attachment *a; - struct sg_table *table; + int ret; a = kzalloc(sizeof(*a), GFP_KERNEL); if (!a) return -ENOMEM; - table = dup_sg_table(&buffer->sg_table); - if (IS_ERR(table)) { + ret = dup_sg_table(&buffer->sg_table, &a->table); + if (ret) { kfree(a); - return -ENOMEM; + return ret; } - a->table = table; a->dev = attachment->dev; INIT_LIST_HEAD(&a->list); a->mapped = false; @@ -120,8 +112,7 @@ static void system_heap_detach(struct dma_buf *dmabuf, list_del(&a->list); mutex_unlock(&buffer->lock); - sg_free_table(a->table); - kfree(a->table); + sg_free_table(&a->table); kfree(a); } @@ -129,7 +120,7 @@ static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attac enum dma_data_direction direction) { struct dma_heap_attachment *a = attachment->priv; - struct sg_table *table = a->table; + struct sg_table *table = &a->table; int ret; ret = dma_map_sgtable(attachment->dev, table, direction, 0); @@ -164,7 +155,7 @@ static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, list_for_each_entry(a, &buffer->attachments, list) { if (!a->mapped) continue; - dma_sync_sgtable_for_cpu(a->dev, a->table, direction); + dma_sync_sgtable_for_cpu(a->dev, &a->table, direction); } mutex_unlock(&buffer->lock); @@ -185,7 +176,7 @@ static int system_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf, list_for_each_entry(a, &buffer->attachments, list) { if (!a->mapped) continue; - dma_sync_sgtable_for_device(a->dev, a->table, direction); + dma_sync_sgtable_for_device(a->dev, &a->table, direction); } mutex_unlock(&buffer->lock); base-commit: 8ffd015db85fea3e15a77027fda6c02ced4d2444 -- 2.49.0.805.g082f7c87e0-goog

4 months, 2 weeks

Re: [PATCH 2/3] dma-buf: Add DMA_BUF_IOCTL_GET_DMA_ADDR

by Christian König

On 4/29/25 08:39, Simona Vetter wrote: > Catching up after spring break, hence the late reply ... > > On Fri, Apr 11, 2025 at 02:34:37PM -0400, Nicolas Dufresne wrote: >> Le jeudi 10 avril 2025 à 16:53 +0200, Bastien Curutchet a écrit : >>> There is no way to transmit the DMA address of a buffer to userspace. >>> Some UIO users need this to handle DMA from userspace. >> >> To me this API is against all safe practice we've been pushing forward >> and has no place in DMA_BUF API. >> >> If this is fine for the UIO subsystem to pass around physicial >> addresses, then make this part of the UIO device ioctl. > > Yeah, this has no business in dma-buf since the entire point of dma-buf > was to stop all the nasty "just pass raw dma addr in userspace" hacks that > preceeded it. > > And over the years since dma-buf landed, we've removed a lot of these, > like dri1 drivers. Or where that's not possible like with fbdev, hid the > raw dma addr uapi behind a Kconfig. > > I concur with the overall sentiment that this should be done in > vfio/iommufd interfaces, maybe with some support added to map dma-buf. I > think patches for that have been floating around for a while, but I lost a > bit the status of where exactly they are. My take away is that we need to have a documented way for special driver specific interfaces in DMA-buf. In other words DMA-buf has some standardized rules of doing things which every implementation should follow. The implementations might of course still have bugs (e.g. allocate memory for a dma_fence operation), but at least we have documented what should be done and what's forbidden. What is still missing in the documentation is the use case when you have for example vfio which wants to talk to iommufd through a specialized interface. This doesn't necessarily needs to be part of DMA-buf, but we should still document "do it this way" because that has already worked in the last ten use cases and we don't want people to re-invent the wheel in a new funky way which then later turns out to not work. Regards, Christian. > > Cheers, Sima > >> >> regards, >> Nicolas >> >>> >>> Add a new dma_buf_ops operation that returns the DMA address. >>> Add a new ioctl to transmit this DMA address to userspace. >>> >>> Signed-off-by: Bastien Curutchet <bastien.curutchet(a)bootlin.com> >>> --- >>> drivers/dma-buf/dma-buf.c | 21 +++++++++++++++++++++ >>> include/linux/dma-buf.h | 1 + >>> include/uapi/linux/dma-buf.h | 1 + >>> 3 files changed, 23 insertions(+) >>> >>> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c >>> index >>> 398418bd9731ad7a3a1f12eaea6a155fa77a22fe..cbbb518981e54e50f479c3d1fcf >>> 6da6971f639c1 100644 >>> --- a/drivers/dma-buf/dma-buf.c >>> +++ b/drivers/dma-buf/dma-buf.c >>> @@ -454,6 +454,24 @@ static long dma_buf_import_sync_file(struct >>> dma_buf *dmabuf, >>> } >>> #endif >>> >>> +static int dma_buf_get_dma_addr(struct dma_buf *dmabuf, u64 __user >>> *arg) >>> +{ >>> + u64 addr; >>> + int ret; >>> + >>> + if (!dmabuf->ops->get_dma_addr) >>> + return -EINVAL; >>> + >>> + ret = dmabuf->ops->get_dma_addr(dmabuf, &addr); >>> + if (ret) >>> + return ret; >>> + >>> + if (copy_to_user(arg, &addr, sizeof(u64))) >>> + return -EFAULT; >>> + >>> + return 0; >>> +} >>> + >>> static long dma_buf_ioctl(struct file *file, >>> unsigned int cmd, unsigned long arg) >>> { >>> @@ -504,6 +522,9 @@ static long dma_buf_ioctl(struct file *file, >>> return dma_buf_import_sync_file(dmabuf, (const void >>> __user *)arg); >>> #endif >>> >>> + case DMA_BUF_IOCTL_GET_DMA_ADDR: >>> + return dma_buf_get_dma_addr(dmabuf, (u64 __user >>> *)arg); >>> + >>> default: >>> return -ENOTTY; >>> } >>> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h >>> index >>> 36216d28d8bdc01a9c9c47e27c392413f7f6c5fb..ed4bf15d3ce82e7a86323fff459 >>> 699a9bc8baa3b 100644 >>> --- a/include/linux/dma-buf.h >>> +++ b/include/linux/dma-buf.h >>> @@ -285,6 +285,7 @@ struct dma_buf_ops { >>> >>> int (*vmap)(struct dma_buf *dmabuf, struct iosys_map *map); >>> void (*vunmap)(struct dma_buf *dmabuf, struct iosys_map >>> *map); >>> + int (*get_dma_addr)(struct dma_buf *dmabuf, u64 *addr); >>> }; >>> >>> /** >>> diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma- >>> buf.h >>> index >>> 5a6fda66d9adf01438619e7e67fa69f0fec2d88d..f3aba46942042de6a2e3a4cca3e >>> b3f87175e29c9 100644 >>> --- a/include/uapi/linux/dma-buf.h >>> +++ b/include/uapi/linux/dma-buf.h >>> @@ -178,5 +178,6 @@ struct dma_buf_import_sync_file { >>> #define DMA_BUF_SET_NAME_B _IOW(DMA_BUF_BASE, 1, __u64) >>> #define DMA_BUF_IOCTL_EXPORT_SYNC_FILE _IOWR(DMA_BUF_BASE, 2, >>> struct dma_buf_export_sync_file) >>> #define DMA_BUF_IOCTL_IMPORT_SYNC_FILE _IOW(DMA_BUF_BASE, 3, struct >>> dma_buf_import_sync_file) >>> +#define DMA_BUF_IOCTL_GET_DMA_ADDR _IOR(DMA_BUF_BASE, 4, __u64 >>> *) >>> >>> #endif >

4 months, 3 weeks

[PATCH v3 00/33] drm/msm: sparse / "VM_BIND" support

by Rob Clark

From: Rob Clark <robdclark(a)chromium.org> Conversion to DRM GPU VA Manager[1], and adding support for Vulkan Sparse Memory[2] in the form of: 1. A new VM_BIND submitqueue type for executing VM MSM_SUBMIT_BO_OP_MAP/ MAP_NULL/UNMAP commands 2. A new VM_BIND ioctl to allow submitting batches of one or more MAP/MAP_NULL/UNMAP commands to a VM_BIND submitqueue I did not implement support for synchronous VM_BIND commands. Since userspace could just immediately wait for the `SUBMIT` to complete, I don't think we need this extra complexity in the kernel. Synchronous/immediate VM_BIND operations could be implemented with a 2nd VM_BIND submitqueue. The corresponding mesa MR: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32533 Changes in v3: - Switched to seperate VM_BIND ioctl. This makes the UABI a bit cleaner, but OTOH the userspace code was cleaner when the end result of either type of VkQueue lead to the same ioctl. So I'm a bit on the fence. - Switched to doing the gpuvm bookkeeping synchronously, and only deferring the pgtable updates. This avoids needing to hold any resv locks in the fence signaling path, resolving the last shrinker related lockdep complaints. OTOH it means userspace can trigger invalid pgtable updates with multiple VM_BIND queues. In this case, we ensure that unmaps happen completely (to prevent userspace from using this to access free'd pages), mark the context as unusable, and move on with life. - Link to v2: https://lore.kernel.org/all/20250319145425.51935-1-robdclark@gmail.com/ Changes in v2: - Dropped Bibek Kumar Patro's arm-smmu patches[3], which have since been merged. - Pre-allocate all the things, and drop HACK patch which disabled shrinker. This includes ensuring that vm_bo objects are allocated up front, pre- allocating VMA objects, and pre-allocating pages used for pgtable updates. The latter utilizes io_pgtable_cfg callbacks for pgtable alloc/free, that were initially added for panthor. - Add back support for BO dumping for devcoredump. - Link to v1 (RFC): https://lore.kernel.org/dri-devel/20241207161651.410556-1-robdclark@gmail.c… [1] https://www.kernel.org/doc/html/next/gpu/drm-mm.html#drm-gpuvm [2] https://docs.vulkan.org/spec/latest/chapters/sparsemem.html [3] https://patchwork.kernel.org/project/linux-arm-kernel/list/?series=909700 Rob Clark (33): drm/gpuvm: Don't require obj lock in destructor path drm/gpuvm: Allow VAs to hold soft reference to BOs iommu/io-pgtable-arm: Add quirk to quiet WARN_ON() drm/msm: Rename msm_file_private -> msm_context drm/msm: Improve msm_context comments drm/msm: Rename msm_gem_address_space -> msm_gem_vm drm/msm: Remove vram carveout support drm/msm: Collapse vma allocation and initialization drm/msm: Collapse vma close and delete drm/msm: Don't close VMAs on purge drm/msm: drm_gpuvm conversion drm/msm: Convert vm locking drm/msm: Use drm_gpuvm types more drm/msm: Split out helper to get iommu prot flags drm/msm: Add mmu support for non-zero offset drm/msm: Add PRR support drm/msm: Rename msm_gem_vma_purge() -> _unmap() drm/msm: Lazily create context VM drm/msm: Add opt-in for VM_BIND drm/msm: Mark VM as unusable on GPU hangs drm/msm: Add _NO_SHARE flag drm/msm: Crashdump prep for sparse mappings drm/msm: rd dumping prep for sparse mappings drm/msm: Crashdec support for sparse drm/msm: rd dumping support for sparse drm/msm: Extract out syncobj helpers drm/msm: Use DMA_RESV_USAGE_BOOKKEEP/KERNEL drm/msm: Add VM_BIND submitqueue drm/msm: Support IO_PGTABLE_QUIRK_NO_WARN_ON drm/msm: Support pgtable preallocation drm/msm: Split out map/unmap ops drm/msm: Add VM_BIND ioctl drm/msm: Bump UAPI version drivers/gpu/drm/drm_gpuvm.c | 15 +- drivers/gpu/drm/msm/Kconfig | 1 + drivers/gpu/drm/msm/Makefile | 1 + drivers/gpu/drm/msm/adreno/a2xx_gpu.c | 25 +- drivers/gpu/drm/msm/adreno/a2xx_gpummu.c | 5 +- drivers/gpu/drm/msm/adreno/a3xx_gpu.c | 17 +- drivers/gpu/drm/msm/adreno/a4xx_gpu.c | 17 +- drivers/gpu/drm/msm/adreno/a5xx_debugfs.c | 4 +- drivers/gpu/drm/msm/adreno/a5xx_gpu.c | 22 +- drivers/gpu/drm/msm/adreno/a5xx_power.c | 2 +- drivers/gpu/drm/msm/adreno/a5xx_preempt.c | 10 +- drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 32 +- drivers/gpu/drm/msm/adreno/a6xx_gmu.h | 2 +- drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 49 +- drivers/gpu/drm/msm/adreno/a6xx_gpu_state.c | 6 +- drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 10 +- drivers/gpu/drm/msm/adreno/adreno_device.c | 4 - drivers/gpu/drm/msm/adreno/adreno_gpu.c | 88 +- drivers/gpu/drm/msm/adreno/adreno_gpu.h | 23 +- .../drm/msm/disp/dpu1/dpu_encoder_phys_wb.c | 14 +- drivers/gpu/drm/msm/disp/dpu1/dpu_formats.c | 18 +- drivers/gpu/drm/msm/disp/dpu1/dpu_formats.h | 2 +- drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 18 +- drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 14 +- drivers/gpu/drm/msm/disp/dpu1/dpu_plane.h | 4 +- drivers/gpu/drm/msm/disp/mdp4/mdp4_crtc.c | 6 +- drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c | 28 +- drivers/gpu/drm/msm/disp/mdp4/mdp4_plane.c | 12 +- drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c | 4 +- drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c | 19 +- drivers/gpu/drm/msm/disp/mdp5/mdp5_plane.c | 12 +- drivers/gpu/drm/msm/dsi/dsi_host.c | 14 +- drivers/gpu/drm/msm/msm_drv.c | 183 +-- drivers/gpu/drm/msm/msm_drv.h | 35 +- drivers/gpu/drm/msm/msm_fb.c | 18 +- drivers/gpu/drm/msm/msm_fbdev.c | 2 +- drivers/gpu/drm/msm/msm_gem.c | 489 +++---- drivers/gpu/drm/msm/msm_gem.h | 217 ++- drivers/gpu/drm/msm/msm_gem_prime.c | 15 + drivers/gpu/drm/msm/msm_gem_shrinker.c | 4 +- drivers/gpu/drm/msm/msm_gem_submit.c | 295 ++-- drivers/gpu/drm/msm/msm_gem_vma.c | 1265 +++++++++++++++-- drivers/gpu/drm/msm/msm_gpu.c | 171 ++- drivers/gpu/drm/msm/msm_gpu.h | 132 +- drivers/gpu/drm/msm/msm_iommu.c | 298 +++- drivers/gpu/drm/msm/msm_kms.c | 18 +- drivers/gpu/drm/msm/msm_kms.h | 2 +- drivers/gpu/drm/msm/msm_mmu.h | 38 +- drivers/gpu/drm/msm/msm_rd.c | 62 +- drivers/gpu/drm/msm/msm_ringbuffer.c | 4 +- drivers/gpu/drm/msm/msm_submitqueue.c | 86 +- drivers/gpu/drm/msm/msm_syncobj.c | 172 +++ drivers/gpu/drm/msm/msm_syncobj.h | 37 + drivers/iommu/io-pgtable-arm.c | 18 +- include/drm/drm_gpuvm.h | 12 +- include/linux/io-pgtable.h | 8 + include/uapi/drm/msm_drm.h | 149 +- 57 files changed, 3012 insertions(+), 1216 deletions(-) create mode 100644 drivers/gpu/drm/msm/msm_syncobj.c create mode 100644 drivers/gpu/drm/msm/msm_syncobj.h -- 2.49.0

4 months, 3 weeks

Re: [PATCH 4/4] drm/nouveau: Check dma_fence in canonical way

by Christian König

On 4/24/25 15:02, Philipp Stanner wrote: > In nouveau_fence_done(), a fence is checked for being signaled by > manually evaluating the base fence's bits. This can be done in a > canonical manner through dma_fence_is_signaled(). > > Replace the bit-check with dma_fence_is_signaled(). > > Signed-off-by: Philipp Stanner <phasta(a)kernel.org> I think the bit check was used here as fast path optimization because we later call dma_fence_is_signaled() anyway. Feel free to add my acked-by, but honestly what nouveau does here looks rather suspicious to me. Regards, Christian. > --- > drivers/gpu/drm/nouveau/nouveau_fence.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c > index fb9811938c82..d5654e26d5bc 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_fence.c > +++ b/drivers/gpu/drm/nouveau/nouveau_fence.c > @@ -253,7 +253,7 @@ nouveau_fence_done(struct nouveau_fence *fence) > struct nouveau_channel *chan; > unsigned long flags; > > - if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->base.flags)) > + if (dma_fence_is_signaled(&fence->base)) > return true; > > spin_lock_irqsave(&fctx->lock, flags);

4 months, 3 weeks

Re: [PATCH 3/4] drm/nouveau: Simplify nouveau_fence_done()

by Christian König

On 4/24/25 15:02, Philipp Stanner wrote: > nouveau_fence_done() contains an if branch that checks whether a > nouveau_fence has either of the two existing nouveau_fence backend ops, > which will always evaluate to true. > > Remove the surplus check. > > Signed-off-by: Philipp Stanner <phasta(a)kernel.org> Reviewed-by: Christian König <christian.koenig(a)amd.com> > --- > drivers/gpu/drm/nouveau/nouveau_fence.c | 24 +++++++++++------------- > 1 file changed, 11 insertions(+), 13 deletions(-) > > diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c > index 2b79bcb7da16..fb9811938c82 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_fence.c > +++ b/drivers/gpu/drm/nouveau/nouveau_fence.c > @@ -249,21 +249,19 @@ nouveau_fence_emit(struct nouveau_fence *fence) > bool > nouveau_fence_done(struct nouveau_fence *fence) > { > - if (fence->base.ops == &nouveau_fence_ops_legacy || > - fence->base.ops == &nouveau_fence_ops_uevent) { > - struct nouveau_fence_chan *fctx = nouveau_fctx(fence); > - struct nouveau_channel *chan; > - unsigned long flags; > + struct nouveau_fence_chan *fctx = nouveau_fctx(fence); > + struct nouveau_channel *chan; > + unsigned long flags; > > - if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->base.flags)) > - return true; > + if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->base.flags)) > + return true; > + > + spin_lock_irqsave(&fctx->lock, flags); > + chan = rcu_dereference_protected(fence->channel, lockdep_is_held(&fctx->lock)); > + if (chan) > + nouveau_fence_update(chan, fctx); > + spin_unlock_irqrestore(&fctx->lock, flags); > > - spin_lock_irqsave(&fctx->lock, flags); > - chan = rcu_dereference_protected(fence->channel, lockdep_is_held(&fctx->lock)); > - if (chan) > - nouveau_fence_update(chan, fctx); > - spin_unlock_irqrestore(&fctx->lock, flags); > - } > return dma_fence_is_signaled(&fence->base); > } >

4 months, 3 weeks

Re: [PATCH v7 04/11] optee: sync secure world ABI headers

by Jens Wiklander

Hi Rouven, On Fri, Apr 25, 2025 at 3:36 PM Rouven Czerwinski <rouven.czerwinski(a)linaro.org> wrote: > > Hi, > > On Fri, 4 Apr 2025 at 16:31, Jens Wiklander <jens.wiklander(a)linaro.org> wrote: > > > > Update the header files describing the secure world ABI, both with and > > without FF-A. The ABI is extended to deal with protected memory, but as > > usual backward compatible. > > > > Signed-off-by: Jens Wiklander <jens.wiklander(a)linaro.org> > > --- > > drivers/tee/optee/optee_ffa.h | 27 +++++++++--- > > drivers/tee/optee/optee_msg.h | 83 ++++++++++++++++++++++++++++++----- > > drivers/tee/optee/optee_smc.h | 71 +++++++++++++++++++++++++++++- > > 3 files changed, 163 insertions(+), 18 deletions(-) > > > > diff --git a/drivers/tee/optee/optee_ffa.h b/drivers/tee/optee/optee_ffa.h > > index 257735ae5b56..cc257e7956a3 100644 > > --- a/drivers/tee/optee/optee_ffa.h > > +++ b/drivers/tee/optee/optee_ffa.h > > @@ -81,7 +81,7 @@ > > * as the second MSG arg struct for > > * OPTEE_FFA_YIELDING_CALL_WITH_ARG. > > * Bit[31:8]: Reserved (MBZ) > > - * w5: Bitfield of secure world capabilities OPTEE_FFA_SEC_CAP_* below, > > + * w5: Bitfield of OP-TEE capabilities OPTEE_FFA_SEC_CAP_* > > * w6: The maximum secure world notification number > > * w7: Not used (MBZ) > > */ > > @@ -94,6 +94,8 @@ > > #define OPTEE_FFA_SEC_CAP_ASYNC_NOTIF BIT(1) > > /* OP-TEE supports probing for RPMB device if needed */ > > #define OPTEE_FFA_SEC_CAP_RPMB_PROBE BIT(2) > > +/* OP-TEE supports Protected Memory for secure data path */ > > +#define OPTEE_FFA_SEC_CAP_PROTMEM BIT(3) > > > > #define OPTEE_FFA_EXCHANGE_CAPABILITIES OPTEE_FFA_BLOCKING_CALL(2) > > > > @@ -108,7 +110,7 @@ > > * > > * Return register usage: > > * w3: Error code, 0 on success > > - * w4-w7: Note used (MBZ) > > + * w4-w7: Not used (MBZ) > > */ > > #define OPTEE_FFA_UNREGISTER_SHM OPTEE_FFA_BLOCKING_CALL(3) > > > > @@ -119,16 +121,31 @@ > > * Call register usage: > > * w3: Service ID, OPTEE_FFA_ENABLE_ASYNC_NOTIF > > * w4: Notification value to request bottom half processing, should be > > - * less than OPTEE_FFA_MAX_ASYNC_NOTIF_VALUE. > > + * less than OPTEE_FFA_MAX_ASYNC_NOTIF_VALUE > > * w5-w7: Not used (MBZ) > > * > > * Return register usage: > > * w3: Error code, 0 on success > > - * w4-w7: Note used (MBZ) > > + * w4-w7: Not used (MBZ) > > */ > > #define OPTEE_FFA_ENABLE_ASYNC_NOTIF OPTEE_FFA_BLOCKING_CALL(5) > > > > -#define OPTEE_FFA_MAX_ASYNC_NOTIF_VALUE 64 > > +#define OPTEE_FFA_MAX_ASYNC_NOTIF_VALUE 64 > > + > > +/* > > + * Release Protected memory > > + * > > + * Call register usage: > > + * w3: Service ID, OPTEE_FFA_RECLAIM_PROTMEM > > + * w4: Shared memory handle, lower bits > > + * w5: Shared memory handle, higher bits > > + * w6-w7: Not used (MBZ) > > + * > > + * Return register usage: > > + * w3: Error code, 0 on success > > + * w4-w7: Note used (MBZ) > > + */ > > +#define OPTEE_FFA_RELEASE_PROTMEM OPTEE_FFA_BLOCKING_CALL(8) > > > > /* > > * Call with struct optee_msg_arg as argument in the supplied shared memory > > diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h > > index e8840a82b983..22d71d6f110d 100644 > > --- a/drivers/tee/optee/optee_msg.h > > +++ b/drivers/tee/optee/optee_msg.h > > @@ -133,13 +133,13 @@ struct optee_msg_param_rmem { > > }; > > > > /** > > - * struct optee_msg_param_fmem - ffa memory reference parameter > > + * struct optee_msg_param_fmem - FF-A memory reference parameter > > * @offs_lower: Lower bits of offset into shared memory reference > > * @offs_upper: Upper bits of offset into shared memory reference > > * @internal_offs: Internal offset into the first page of shared memory > > * reference > > * @size: Size of the buffer > > - * @global_id: Global identifier of Shared memory > > + * @global_id: Global identifier of the shared memory > > */ > > struct optee_msg_param_fmem { > > u32 offs_low; > > @@ -165,7 +165,7 @@ struct optee_msg_param_value { > > * @attr: attributes > > * @tmem: parameter by temporary memory reference > > * @rmem: parameter by registered memory reference > > - * @fmem: parameter by ffa registered memory reference > > + * @fmem: parameter by FF-A registered memory reference > > * @value: parameter by opaque value > > * @octets: parameter by octet string > > * > > @@ -296,6 +296,18 @@ struct optee_msg_arg { > > */ > > #define OPTEE_MSG_FUNCID_GET_OS_REVISION 0x0001 > > > > +/* > > + * Values used in OPTEE_MSG_CMD_LEND_PROTMEM below > > + * OPTEE_MSG_PROTMEM_RESERVED Reserved > > + * OPTEE_MSG_PROTMEM_SECURE_VIDEO_PLAY Secure Video Playback > > + * OPTEE_MSG_PROTMEM_TRUSTED_UI Trused UI > > + * OPTEE_MSG_PROTMEM_SECURE_VIDEO_RECORD Secure Video Recording > > + */ > > +#define OPTEE_MSG_PROTMEM_RESERVED 0 > > +#define OPTEE_MSG_PROTMEM_SECURE_VIDEO_PLAY 1 > > +#define OPTEE_MSG_PROTMEM_TRUSTED_UI 2 > > +#define OPTEE_MSG_PROTMEM_SECURE_VIDEO_RECORD 3 > > + > > /* > > * Do a secure call with struct optee_msg_arg as argument > > * The OPTEE_MSG_CMD_* below defines what goes in struct optee_msg_arg::cmd > > @@ -337,15 +349,62 @@ struct optee_msg_arg { > > * OPTEE_MSG_CMD_STOP_ASYNC_NOTIF informs secure world that from now is > > * normal world unable to process asynchronous notifications. Typically > > * used when the driver is shut down. > > + * > > + * OPTEE_MSG_CMD_LEND_PROTMEM lends protected memory. The passed normal > > + * physical memory is protected from normal world access. The memory > > + * should be unmapped prior to this call since it becomes inaccessible > > + * during the request. > > + * Parameters are passed as: > > + * [in] param[0].attr OPTEE_MSG_ATTR_TYPE_VALUE_INPUT > > + * [in] param[0].u.value.a OPTEE_MSG_PROTMEM_* defined above > > + * [in] param[1].attr OPTEE_MSG_ATTR_TYPE_TMEM_INPUT > > + * [in] param[1].u.tmem.buf_ptr physical address > > + * [in] param[1].u.tmem.size size > > + * [in] param[1].u.tmem.shm_ref holds protected memory reference > > + * > > + * OPTEE_MSG_CMD_RECLAIM_PROTMEM reclaims a previously lent protected > > + * memory reference. The physical memory is accessible by the normal world > > + * after this function has return and can be mapped again. The information > > + * is passed as: > > + * [in] param[0].attr OPTEE_MSG_ATTR_TYPE_VALUE_INPUT > > + * [in] param[0].u.value.a holds protected memory cookie > > + * > > + * OPTEE_MSG_CMD_GET_PROTMEM_CONFIG get configuration for a specific > > + * protected memory use case. Parameters are passed as: > > + * [in] param[0].attr OPTEE_MSG_ATTR_TYPE_VALUE_INOUT > > + * [in] param[0].value.a OPTEE_MSG_PROTMEM_* > > + * [in] param[1].attr OPTEE_MSG_ATTR_TYPE_{R,F}MEM_OUTPUT > > + * [in] param[1].u.{r,f}mem Buffer or NULL > > + * [in] param[1].u.{r,f}mem.size Provided size of buffer or 0 for query > > + * output for the protected use case: > > + * [out] param[0].value.a Minimal size of protected memory > > + * [out] param[0].value.b Required alignment of size and start of > > + * protected memory > > + * [out] param[1].{r,f}mem.size Size of output data > > + * [out] param[1].{r,f}mem If non-NULL, contains an array of > > + * uint16_t holding endpoints that > > + * must be included when lending > > + * memory for this use case > > + * > > + * OPTEE_MSG_CMD_ASSIGN_PROTMEM assigns use-case to protected memory > > + * previously lent using the FFA_LEND framework ABI. Parameters are passed > > + * as: > > + * [in] param[0].attr OPTEE_MSG_ATTR_TYPE_VALUE_INPUT > > + * [in] param[0].u.value.a holds protected memory cookie > > + * [in] param[0].u.value.b OPTEE_MSG_PROTMEM_* defined above > > */ > > -#define OPTEE_MSG_CMD_OPEN_SESSION 0 > > -#define OPTEE_MSG_CMD_INVOKE_COMMAND 1 > > -#define OPTEE_MSG_CMD_CLOSE_SESSION 2 > > -#define OPTEE_MSG_CMD_CANCEL 3 > > -#define OPTEE_MSG_CMD_REGISTER_SHM 4 > > -#define OPTEE_MSG_CMD_UNREGISTER_SHM 5 > > -#define OPTEE_MSG_CMD_DO_BOTTOM_HALF 6 > > -#define OPTEE_MSG_CMD_STOP_ASYNC_NOTIF 7 > > -#define OPTEE_MSG_FUNCID_CALL_WITH_ARG 0x0004 > > +#define OPTEE_MSG_CMD_OPEN_SESSION 0 > > +#define OPTEE_MSG_CMD_INVOKE_COMMAND 1 > > +#define OPTEE_MSG_CMD_CLOSE_SESSION 2 > > +#define OPTEE_MSG_CMD_CANCEL 3 > > +#define OPTEE_MSG_CMD_REGISTER_SHM 4 > > +#define OPTEE_MSG_CMD_UNREGISTER_SHM 5 > > +#define OPTEE_MSG_CMD_DO_BOTTOM_HALF 6 > > +#define OPTEE_MSG_CMD_STOP_ASYNC_NOTIF 7 > > +#define OPTEE_MSG_CMD_LEND_PROTMEM 8 > > +#define OPTEE_MSG_CMD_RECLAIM_PROTMEM 9 > > +#define OPTEE_MSG_CMD_GET_PROTMEM_CONFIG 10 > > +#define OPTEE_MSG_CMD_ASSIGN_PROTMEM 11 > > +#define OPTEE_MSG_FUNCID_CALL_WITH_ARG 0x0004 > > > > #endif /* _OPTEE_MSG_H */ > > diff --git a/drivers/tee/optee/optee_smc.h b/drivers/tee/optee/optee_smc.h > > index 879426300821..b17e81f464a3 100644 > > --- a/drivers/tee/optee/optee_smc.h > > +++ b/drivers/tee/optee/optee_smc.h > > @@ -264,7 +264,6 @@ struct optee_smc_get_shm_config_result { > > #define OPTEE_SMC_SEC_CAP_HAVE_RESERVED_SHM BIT(0) > > /* Secure world can communicate via previously unregistered shared memory */ > > #define OPTEE_SMC_SEC_CAP_UNREGISTERED_SHM BIT(1) > > - > > /* > > * Secure world supports commands "register/unregister shared memory", > > * secure world accepts command buffers located in any parts of non-secure RAM > > @@ -280,6 +279,10 @@ struct optee_smc_get_shm_config_result { > > #define OPTEE_SMC_SEC_CAP_RPC_ARG BIT(6) > > /* Secure world supports probing for RPMB device if needed */ > > #define OPTEE_SMC_SEC_CAP_RPMB_PROBE BIT(7) > > +/* Secure world supports protected memory */ > > +#define OPTEE_SMC_SEC_CAP_PROTMEM BIT(8) > > +/* Secure world supports dynamic protected memory */ > > +#define OPTEE_SMC_SEC_CAP_DYNAMIC_PROTMEM BIT(9) > > > > #define OPTEE_SMC_FUNCID_EXCHANGE_CAPABILITIES 9 > > #define OPTEE_SMC_EXCHANGE_CAPABILITIES \ > > @@ -451,6 +454,72 @@ struct optee_smc_disable_shm_cache_result { > > > > /* See OPTEE_SMC_CALL_WITH_REGD_ARG above */ > > #define OPTEE_SMC_FUNCID_CALL_WITH_REGD_ARG 19 > > +/* > > + * Get protected memory config > > + * > > + * Returns the protected memory config. > > + * > > + * Call register usage: > > + * a0 SMC Function ID, OPTEE_SMC_GET_PROTMEM_CONFIG > > + * a2-6 Not used, must be zero > > + * a7 Hypervisor Client ID register > > + * > > + * Have config return register usage: > > + * a0 OPTEE_SMC_RETURN_OK > > + * a1 Physical address of start of protected memory > > + * a2 Size of protected memory > > + * a3 Not used > > + * a4-7 Preserved > > + * > > + * Not available register usage: > > + * a0 OPTEE_SMC_RETURN_ENOTAVAIL > > + * a1-3 Not used > > + * a4-7 Preserved > > + */ > > +#define OPTEE_SMC_FUNCID_GET_PROTMEM_CONFIG 20 > > +#define OPTEE_SMC_GET_PROTMEM_CONFIG \ > > + OPTEE_SMC_FAST_CALL_VAL(OPTEE_SMC_FUNCID_GET_PROTMEM_CONFIG) > > + > > +struct optee_smc_get_protmem_config_result { > > + unsigned long status; > > + unsigned long start; > > + unsigned long size; > > + unsigned long flags; > > The ABI comment does not document a flags return argument, either > this can be removed or the ABI comment needs to be fixed. Sure, I'll remove the field. > Same for > > +}; > > + > > +/* > > + * Get dynamic protected memory config > > + * > > + * Returns the dynamic protected memory config. > > + * > > + * Call register usage: > > + * a0 SMC Function ID, OPTEE_SMC_GET_DYN_SHM_CONFIG > > should be OPTEE_SMC_GET_DYN_PROTMEM_CONFIG Thanks, I'll update. > > > + * a2-6 Not used, must be zero > > + * a7 Hypervisor Client ID register > > + * > > + * Have config return register usage: > > + * a0 OPTEE_SMC_RETURN_OK > > + * a1 Minamal size of protected memory > > Nit: Typo, should be "Minimal" Yes, I'll update. Cheers, Jens > > > + * a2 Required alignment of size and start of registered protected memory > > + * a3 Not used > > + * a4-7 Preserved > > + * > > + * Not available register usage: > > + * a0 OPTEE_SMC_RETURN_ENOTAVAIL > > + * a1-3 Not used > > + * a4-7 Preserved > > + */ > > + > > +#define OPTEE_SMC_FUNCID_GET_DYN_PROTMEM_CONFIG 21 > > +#define OPTEE_SMC_GET_DYN_PROTMEM_CONFIG \ > > + OPTEE_SMC_FAST_CALL_VAL(OPTEE_SMC_FUNCID_GET_DYN_PROTMEM_CONFIG) > > + > > +struct optee_smc_get_dyn_protmem_config_result { > > + unsigned long status; > > + unsigned long size; > > + unsigned long align; > > + unsigned long flags; > > +}; > > > > /* > > * Resume from RPC (for example after processing a foreign interrupt) > > -- > > 2.43.0 > > - Rouven

4 months, 3 weeks

[PATCH AUTOSEL 6.13 15/34] drm/amdgpu: allow pinning DMA-bufs into VRAM if all importers can do P2P

by Sasha Levin

From: Christian König <christian.koenig(a)amd.com> [ Upstream commit f5e7fabd1f5c65b2e077efcdb118cfa67eae7311 ] Try pinning into VRAM to allow P2P with RDMA NICs without ODP support if all attachments can do P2P. If any attachment can't do P2P just pin into GTT instead. Acked-by: Simona Vetter <simona.vetter(a)ffwll.ch> Signed-off-by: Christian König <christian.koenig(a)amd.com> Signed-off-by: Felix Kuehling <felix.kuehling(a)amd.com> Reviewed-by: Felix Kuehling <felix.kuehling(a)amd.com> Tested-by: Pak Nin Lui <pak.lui(a)amd.com> Cc: Simona Vetter <simona.vetter(a)ffwll.ch> Signed-off-by: Alex Deucher <alexander.deucher(a)amd.com> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 25 +++++++++++++++------ 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c index 8e81a83d37d84..83390143c2e9f 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c @@ -72,11 +72,25 @@ static int amdgpu_dma_buf_attach(struct dma_buf *dmabuf, */ static int amdgpu_dma_buf_pin(struct dma_buf_attachment *attach) { - struct drm_gem_object *obj = attach->dmabuf->priv; - struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj); + struct dma_buf *dmabuf = attach->dmabuf; + struct amdgpu_bo *bo = gem_to_amdgpu_bo(dmabuf->priv); + u32 domains = bo->preferred_domains; - /* pin buffer into GTT */ - return amdgpu_bo_pin(bo, AMDGPU_GEM_DOMAIN_GTT); + dma_resv_assert_held(dmabuf->resv); + + /* + * Try pinning into VRAM to allow P2P with RDMA NICs without ODP + * support if all attachments can do P2P. If any attachment can't do + * P2P just pin into GTT instead. + */ + list_for_each_entry(attach, &dmabuf->attachments, node) + if (!attach->peer2peer) + domains &= ~AMDGPU_GEM_DOMAIN_VRAM; + + if (domains & AMDGPU_GEM_DOMAIN_VRAM) + bo->flags |= AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED; + + return amdgpu_bo_pin(bo, domains); } /** @@ -131,9 +145,6 @@ static struct sg_table *amdgpu_dma_buf_map(struct dma_buf_attachment *attach, r = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx); if (r) return ERR_PTR(r); - - } else if (bo->tbo.resource->mem_type != TTM_PL_TT) { - return ERR_PTR(-EBUSY); } switch (bo->tbo.resource->mem_type) { -- 2.39.5

4 months, 3 weeks

[PATCH v3 0/2] dma-buf: heaps: Support carved-out heaps

by Maxime Ripard

Hi, This series is the follow-up of the discussion that John and I had some time ago here: https://lore.kernel.org/all/CANDhNCquJn6bH3KxKf65BWiTYLVqSd9892-xtFDHHqqyrr… The initial problem we were discussing was that I'm currently working on a platform which has a memory layout with ECC enabled. However, enabling the ECC has a number of drawbacks on that platform: lower performance, increased memory usage, etc. So for things like framebuffers, the trade-off isn't great and thus there's a memory region with ECC disabled to allocate from for such use cases. After a suggestion from John, I chose to first start using heap allocations flags to allow for userspace to ask for a particular ECC setup. This is then backed by a new heap type that runs from reserved memory chunks flagged as such, and the existing DT properties to specify the ECC properties. After further discussion, it was considered that flags were not the right solution, and relying on the names of the heaps would be enough to let userspace know the kind of buffer it deals with. Thus, even though the uAPI part of it has been dropped in this second version, we still need a driver to create heaps out of carved-out memory regions. In addition to the original usecase, a similar driver can be found in BSPs from most vendors, so I believe it would be a useful addition to the kernel. I submitted a draft PR to the DT schema for the bindings used in this PR: https://github.com/devicetree-org/dt-schema/pull/138 Let me know what you think, Maxime Signed-off-by: Maxime Ripard <mripard(a)kernel.org> --- Changes in v3: - Reworked global variable patch - Link to v2: https://lore.kernel.org/r/20250401-dma-buf-ecc-heap-v2-0-043fd006a1af@kerne… Changes in v2: - Add vmap/vunmap operations - Drop ECC flags uapi - Rebase on top of 6.14 - Link to v1: https://lore.kernel.org/r/20240515-dma-buf-ecc-heap-v1-0-54cbbd049511@kerne… --- Maxime Ripard (2): dma-buf: heaps: system: Remove global variable dma-buf: heaps: Introduce a new heap for reserved memory drivers/dma-buf/heaps/Kconfig | 8 + drivers/dma-buf/heaps/Makefile | 1 + drivers/dma-buf/heaps/carveout_heap.c | 360 ++++++++++++++++++++++++++++++++++ drivers/dma-buf/heaps/system_heap.c | 3 +- 4 files changed, 370 insertions(+), 2 deletions(-) --- base-commit: fcbf30774e82a441890b722bf0c26542fb82150f change-id: 20240515-dma-buf-ecc-heap-28a311d2c94e Best regards, -- Maxime Ripard <mripard(a)kernel.org>

4 months, 3 weeks

Re: [PATCH 2/4] bpf: Add dmabuf iterator

by T.J. Mercier

On Tue, Apr 22, 2025 at 4:01 PM Alexei Starovoitov <alexei.starovoitov(a)gmail.com> wrote: > > On Tue, Apr 22, 2025 at 12:57 PM T.J. Mercier <tjmercier(a)google.com> wrote: > > > > On Mon, Apr 21, 2025 at 4:39 PM Alexei Starovoitov > > <alexei.starovoitov(a)gmail.com> wrote: > > > > > > On Mon, Apr 21, 2025 at 1:40 PM T.J. Mercier <tjmercier(a)google.com> wrote: > > > > > > > > > > new file mode 100644 > > > > > > index 000000000000..b4b8be1d6aa4 > > > > > > --- /dev/null > > > > > > +++ b/kernel/bpf/dmabuf_iter.c > > > > > > > > > > Maybe we should add this file to drivers/dma-buf. I would like to > > > > > hear other folks thoughts on this. > > > > > > > > This is fine with me, and would save us the extra > > > > CONFIG_DMA_SHARED_BUFFER check that's currently needed in > > > > kernel/bpf/Makefile but would require checking CONFIG_BPF instead. > > > > Sumit / Christian any objections to moving the dmabuf bpf iterator > > > > implementation into drivers/dma-buf? > > > > > > The driver directory would need to 'depends on BPF_SYSCALL'. > > > Are you sure you want this? > > > imo kernel/bpf/ is fine for this. > > > > I don't have a strong preference so either way is fine with me. The > > main difference I see is maintainership. > > > > > You also probably want > > > .feature = BPF_ITER_RESCHED > > > in bpf_dmabuf_reg_info. > > > > Thank you, this looks like a good idea. > > > > > Also have you considered open coded iterator for dmabufs? > > > Would it help with the interface to user space? > > > > I read through the open coded iterator patches, and it looks like they > > would be slightly more efficient by avoiding seq_file overhead. As far > > as the interface to userspace, for the purpose of replacing what's > > currently exposed by CONFIG_DMABUF_SYSFS_STATS I don't think there is > > a difference. However it looks like if I were to try to replace all of > > our userspace analysis of dmabufs with a single bpf program then an > > open coded iterator would make that much easier. I had not considered > > attempting that. > > > > One problem I see with open coded iterators is that support is much > > more recent (2023 vs 2020). We support longterm stable kernels (back > > to 5.4 currently but probably 5.10 by the time this would be used), so > > it seems like it would be harder to backport the kernel support for an > > open-coded iterator that far since it only goes back as far as 6.6 > > now. Actually it doesn't look like it is possible while also > > maintaining the stable ABI we provide to device vendors. Which means > > we couldn't get rid of the dmabuf sysfs stats userspace dependency > > until 6.1 EOL in Dec. 2027. :\ So I'm in favor of a traditional bpf > > iterator here for now. > > Fair enough, but please implement both and backport only > the old style pinned iterator. Ok, will do. > The code will be mostly shared between them. > bpf_iter_dmabuf_new/_next will be more flexible with more > options to return data to user space. Like android can invent > their own binary format. Pack into it in a bpf prog, send to > bpf ringbuf and unmarshal efficiently in user space. > Instead of being limited to text output that pinned iterators > are supposed to do usually. Also a neat idea! > You can do binary with bpf_seq_write() too, but it's rare. > > Also please provide full bpf prog that you'll use in production > in a selftest instead of trivial: > +SEC("iter/dmabuf") > +int dmabuf_collector(struct bpf_iter__dmabuf *ctx) > > just to make sure it's tested end to end and future changes > won't break it. The final bpf program should be something pretty close to that, but I'll start working on the AOSP side as well so I can put up patches. > > pw-bot: cr

4 months, 3 weeks

Re: [PATCH v2 0/2] dma-buf: heaps: Use constant name for CMA heap

by Sumit Semwal

Hello Jared, On Wed, 23 Apr 2025 at 00:49, Jared Kangas <jkangas(a)redhat.com> wrote: > > Hi all, > > This patch series is based on a previous discussion around CMA heap > naming. [1] The heap's name depends on the device name, which is > generally "reserved", "linux,cma", or "default-pool", but could be any > arbitrary name given to the default CMA area in the devicetree. For a > consistent userspace interface, the series introduces a constant name > for the CMA heap, and for backwards compatibility, an additional Kconfig > that controls the creation of a legacy-named heap with the same CMA > backing. > > The ideas to handle backwards compatibility in [1] are to either use a > symlink or add a heap node with a duplicate minor. However, I assume > that we don't want to create symlinks in /dev from module initcalls, and > attempting to duplicate minors would cause device_create() to fail. > Because of these drawbacks, after brainstorming with Maxime Ripard, I > went with creating a new node in devtmpfs with its own minor. This > admittedly makes it a little unclear that the old and new nodes are > backed by the same heap when both are present. The only approach that I > think would provide total clarity on this in userspace is symlinking, > which seemed like a fairly involved solution for devtmpfs, but if I'm > wrong on this, please let me know. Thanks indeed for this patch; just one minor nit: the link referred to as [1] here seems to be missing. Could you please add it? This would make it easier to follow the chain of discussion in posterity. > > Changelog: > v2: Use tabs instead of spaces for large vertical alignment. > > Jared Kangas (2): > dma-buf: heaps: Parameterize heap name in __add_cma_heap() > dma-buf: heaps: Give default CMA heap a fixed name > > Documentation/userspace-api/dma-buf-heaps.rst | 11 ++++--- > drivers/dma-buf/heaps/Kconfig | 10 +++++++ > drivers/dma-buf/heaps/cma_heap.c | 30 ++++++++++++++----- > 3 files changed, 40 insertions(+), 11 deletions(-) > > -- > 2.49.0 > Best, Sumit

4 months, 3 weeks

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