Linaro-mm-sig August 2026

linaro-mm-sig@lists.linaro.org

25 participants
81 discussions

Re: [PATCH v5 3/9] vfio/pci: Add a helper to look up PFNs for DMABUFs

by Matt Evans

Hi Praan, On 30/07/2026 23:55, Pranjal Shrivastava wrote: > On Wed, Jul 15, 2026 at 06:47:26PM +0100, Matt Evans wrote: >> Add vfio_pci_dma_buf_find_pfn(), which a VMA fault handler can use to >> find a PFN. >> >> This supports multi-range DMABUFs, which typically would be used to >> represent scattered spans but might even represent overlapping or >> aliasing spans of PFNs. >> >> Because this is intended to be used in vfio_pci_core.c, we also need >> to expose the struct vfio_pci_dma_buf in the vfio_pci_priv.h header. >> >> Signed-off-by: Matt Evans <matt(a)ozlabs.org> >> --- >> drivers/vfio/pci/vfio_pci_dmabuf.c | 153 ++++++++++++++++++++++++++--- >> drivers/vfio/pci/vfio_pci_priv.h | 20 ++++ >> 2 files changed, 160 insertions(+), 13 deletions(-) >> >> diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c >> index c16f460c01d6..7c047400dfd1 100644 >> --- a/drivers/vfio/pci/vfio_pci_dmabuf.c >> +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c >> @@ -9,19 +9,6 @@ >> >> MODULE_IMPORT_NS("DMA_BUF"); >> >> -struct vfio_pci_dma_buf { >> - struct dma_buf *dmabuf; >> - struct vfio_pci_core_device *vdev; >> - struct list_head dmabufs_elm; >> - size_t size; >> - struct phys_vec *phys_vec; >> - struct p2pdma_provider *provider; >> - u32 nr_ranges; >> - struct kref kref; >> - struct completion comp; >> - u8 revoked : 1; >> -}; >> - >> static int vfio_pci_dma_buf_attach(struct dma_buf *dmabuf, >> struct dma_buf_attachment *attachment) >> { >> @@ -106,6 +93,146 @@ static const struct dma_buf_ops vfio_pci_dmabuf_ops = { >> .release = vfio_pci_dma_buf_release, >> }; >> >> +int vfio_pci_dma_buf_find_pfn(struct vfio_pci_dma_buf *priv, >> + struct vm_area_struct *vma, >> + unsigned long fault_addr, >> + unsigned int order, >> + unsigned long *out_pfn) >> +{ >> + /* >> + * Given a VMA (start, end, pgoffs) and a fault address, >> + * search the corresponding DMABUF's phys_vec[] to find the >> + * range representing the address's offset into the VMA, and >> + * its PFN. >> + * >> + * The phys_vec[] ranges represent contiguous spans of VAs >> + * upwards from the buffer offset 0; the actual PFNs might be >> + * in any order, overlap/alias, etc. Calculate an offset of >> + * the desired page given VMA start/pgoff and address, then >> + * search upwards from 0 to find which span contains it. >> + * >> + * On success, a valid PFN for a page sized by 'order' is >> + * returned into out_pfn. >> + * >> + * Failure occurs if: >> + * - A hugepage would cross the edge of the VMA, >> + * - A hugepage isn't entirely contained within a range >> + * (including where it straddles the boundary between >> + * ranges), >> + * - We find a range, but the final PFN isn't aligned to the >> + * requested order. >> + * >> + * Upon failure, -EAGAIN is returned and the caller is >> + * expected to try again with a smaller order, which will >> + * eventually succeed (order=0 will always work). >> + * >> + * It's suboptimal if DMABUFs are created with neighbouring >> + * ranges that are physically contiguous, since hugepages >> + * can't straddle range boundaries. (The construction of the >> + * ranges should merge them in this case.) >> + * >> + * Finally, vma_pgoff_adjust is used with a DMABUF created for >> + * a VFIO BAR mmap: a BAR mapped with vm_pgoff > 0 creates a >> + * DMABUF such that byte 0 of the VMA corresponds to byte 0 of >> + * the DMABUF and byte 'vm_pgoff << PAGE_SHIFT' into the BAR. >> + * To avoid double-offsetting in this scenario, subtracting >> + * vma_pgoff_adjust from this (non-zero) vm_pgoff generates >> + * the effective offset. >> + */ >> + >> + const unsigned long pagesize = PAGE_SIZE << order; >> + unsigned long vma_off = ((vma->vm_pgoff - priv->vma_pgoff_adjust) << >> + PAGE_SHIFT) & VFIO_PCI_OFFSET_MASK; > > Maybe I'm getting ahead of myself here.. but it seems like this > restricts us to only mapping DMABUFs at offsets < 1TB due to the > VFIO_PCI_OFFSET_MASK (since we have HBMs on PCI devices now, hitting 1TB > may not be a very distant future). This is a really good question, thanks for raisiing it. It is not too forward-thinking at all. > While I understand this mask is needed to drop the BAR encoding in the > high bits. > > My worry is, if in the future a user were to export a massive > contiguous DMABUF (e.g., >1TB of aggregated HBM) and tried to mmap deep > into it (passing an offset >= 1TB), this bitwise AND would silently drop > the high bits, leading to silent data corruption. One of the big advantages of DMABUF export was that the range could be huge and unencumbered by the VFIO_PCI_OFFSET_SHIFT of the traditional mmap() interface. It's a way to mmap huge BARs without having to change the user-visible shift). So definitely this is a relevant concern. > I think we should explicitly reject such an mmap with -EINVAL like: > > +const unsigned long pagesize = PAGE_SIZE << order; > +unsigned long vma_off = (vma->vm_pgoff - priv->vma_pgoff_adjust) << PAGE_SHIFT; > > +/* > + * Prevent silent wrap-around if the user mmaps a DMABUF at an > + * offset greater than the VFIO index mask allows. > + */ > +if (unlikely(vma_off > VFIO_PCI_OFFSET_MASK)) > + return -EINVAL; > > +vma_off &= VFIO_PCI_OFFSET_MASK; Agreed, for now this absolutely should not silently wrap if the offset is > 1TB, and we live with the restriction that a DMABUF sized >1TB can't be mapped with such an offset. (We can still, say, map all of a 16TB DMABUF with offset=0, which is good.). I'll add a check, thanks for pointing this out. I suggest as something to revisit later, we flag for a DMABUF (maybe an evolution of vma_pgoff_adjust) to differentiate whether this masking needs to be applied (traditional mmap() path) or not (DMABUF mmap()), and then offsets can be arbitrarily large. Cheers, Matt >> + unsigned long rounded_page_addr = ALIGN_DOWN(fault_addr, pagesize); >> + unsigned long rounded_page_end = rounded_page_addr + pagesize; >> + unsigned long fault_offset; >> + unsigned long fault_offset_end; >> + unsigned long range_start_offset = 0; >> + unsigned int i; >> + int ret; >> + > > > Thanks, > Praan

2 weeks, 3 days

Re: [PATCH v5 11/16] nvme-pci: add SGL support for the dmabuf path

by Christoph Hellwig

Looks good: Reviewed-by: Christoph Hellwig <hch(a)lst.de>

2 weeks, 3 days

Re: [PATCH v5 10/16] nvme-pci: rename nvme_pci_sgl_set_data to nvme_pci_dma_iter_set_sgl

by Christoph Hellwig

Looks good: Reviewed-by: Christoph Hellwig <hch(a)lst.de>

2 weeks, 3 days

Re: [PATCH v5 09/16] nvme-pci: implement dma-buf backed requests

by Christoph Hellwig

> +static blk_status_t nvme_rq_setup_dmabuf_map(struct request *req, > + struct nvme_queue *nvmeq) Two tab indents for prototype continuations everywhere please.

2 weeks, 3 days

Re: [PATCH v5 07/16] block: introduce dma map backed bio type

by Christoph Hellwig

On Sat, Aug 01, 2026 at 04:46:19PM +0100, Pavel Begunkov wrote: > Premapped buffers don't require a generic bio_vec since these have > already been dma mapped. Repurpose the bi_io_vec space to strore dmabuf > maps as they are mutually exclusive. > > Suggested-by: Keith Busch <kbusch(a)kernel.org> > Signed-off-by: Pavel Begunkov <asml.silence(a)gmail.com> > --- > block/bio.c | 15 +++++++++++++-- > block/blk-merge.c | 37 +++++++++++++++++++++++++++++++++++++ > block/fops.c | 2 +- > include/linux/bio.h | 9 +++++---- > include/linux/blk-mq.h | 7 +++++++ > include/linux/blk_types.h | 14 +++++++++++++- > include/linux/bvec.h | 3 ++- > 7 files changed, 78 insertions(+), 9 deletions(-) > > diff --git a/block/bio.c b/block/bio.c > index 898b2f5ef8c8..1602eab05761 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -860,7 +860,11 @@ static int __bio_clone(struct bio *bio, struct bio *bio_src, gfp_t gfp) > bio->bi_write_hint = bio_src->bi_write_hint; > bio->bi_write_stream = bio_src->bi_write_stream; > bio->bi_iter = bio_src->bi_iter; > - bio->bi_io_vec = bio_src->bi_io_vec; > + > + if (op_is_dmabuf(bio->bi_opf)) > + bio->bi_dmabuf_map = bio_src->bi_dmabuf_map; > + else > + bio->bi_io_vec = bio_src->bi_io_vec; > > if (bio->bi_bdev) { > if (bio->bi_bdev == bio_src->bi_bdev && > @@ -1183,16 +1187,23 @@ EXPORT_SYMBOL_GPL(__bio_release_pages); > > bool bio_iov_iter_set(struct bio *bio, const struct iov_iter *iter) > { > - if (!iov_iter_is_bvec(iter)) > + if (!iov_iter_is_bvec(iter) && !iov_iter_is_dmabuf_map(iter)) > return false; > > WARN_ON_ONCE(bio->bi_max_vecs); > > + static_assert(offsetof(struct bio, bi_io_vec) == > + offsetof(struct bio, bi_dmabuf_map)); > + static_assert(offsetof(struct iov_iter, bvec) == > + offsetof(struct iov_iter, dmabuf_map)); > + > bio->bi_io_vec = (struct bio_vec *)iter->bvec; > bio->bi_iter.bi_idx = 0; > bio->bi_iter.bi_offset = iter->iov_offset; > bio->bi_iter.bi_size = iov_iter_count(iter); > bio_set_flag(bio, BIO_CLONED); > + if (iov_iter_is_dmabuf_map(iter)) > + bio->bi_opf |= REQ_NOMERGE | REQ_DMABUF; > return true; > } > > diff --git a/block/blk-merge.c b/block/blk-merge.c > index 258a726071d1..1beedc42a85d 100644 > --- a/block/blk-merge.c > +++ b/block/blk-merge.c > @@ -9,6 +9,7 @@ > #include <linux/blk-integrity.h> > #include <linux/part_stat.h> > #include <linux/blk-cgroup.h> > +#include <linux/dma-buf-io.h> > > #include <trace/events/block.h> > > @@ -319,6 +320,28 @@ static inline unsigned int bvec_seg_gap(struct bio_vec *bvprv, > return bv->bv_offset | (bvprv->bv_offset + bvprv->bv_len); > } > > +static inline int bio_split_io_at_dmabuf(struct bio *bio, > + const struct queue_limits *lim, unsigned *segs, > + unsigned max_bytes, unsigned len_align_mask, > + unsigned start_align_mask) > +{ > + unsigned bytes = min(bio->bi_iter.bi_size, max_bytes); > + unsigned seg_shift = bio->bi_dmabuf_map->seg_shift; > + unsigned offset = bio->bi_iter.bi_offset & ((1U << seg_shift) - 1); > + > + if ((bio->bi_iter.bi_offset & start_align_mask) || > + (bio->bi_iter.bi_size & len_align_mask)) > + return -EINVAL; > + > + /* single contiguous range into the dma-buf */ > + *segs = 1; > + > + bytes = min(bytes, ((unsigned)lim->max_segments << seg_shift) - offset); I guess ->seg_shift is some sort of encoding of a max segment size? Comments please.

2 weeks, 3 days

Re: [PATCH v5 01/16] dma-buf: introduce initial file I/O infrastructure

by Christoph Hellwig

On Sat, Aug 01, 2026 at 04:46:13PM +0100, Pavel Begunkov wrote: > The goal is to be able to natively use dma-buf in the read-write / IO > path. This patch adds basic building blocks serving as a glue and API > between drivers and upper layer subsystems providing the uAPI. Later > patches implement it for NVMe raw block devices and expose it to the > user space via io_uring. > > There are two main objects. struct dma_buf_io_ctx and struct > dma_buf_io_map. The ctx is used during initial registration and serves > as an interface between the upper layer user like io_uring and to the > importer subsystem / driver. The map represents the actual dma map > established for the target device[s] with dma_buf_map_attachment() and > stored in a device specific format. The context is created via a new > file operation ->init_dma_buf_io_ctx. > > The ctx-map separation exists to support map invalidation (see > dma_buf_io_invalidate_mappings()). A ctx can create > multiple maps during its lifetime, but there can only be no more than > one (active) map attached to it. Invalidation drops the active map > if present, and the next map will only be attempted to be created > once there is a new request that wants to use the dma-buf IO ctx. > > The primary task of the dma_buf_io_map object is to count requests > using it and to wait for their completion when we want to destroy the > DMA map. Invalidation is delayed by inserting a dma fence, which is > signaled when all flight requests are completed. > > [un]mapping and any work with dma addresses is delegated to the > importer driver via an ops table stored in the ctx, see struct > dma_buf_io_ops. Only the target driver / subsystem knows about devices > it wants to use the dma-buf with, especially in case of multi-device > filesystems or stacking in the future. > > Signed-off-by: Pavel Begunkov <asml.silence(a)gmail.com> > --- > drivers/dma-buf/Makefile | 2 +- > drivers/dma-buf/dma-buf-io.c | 278 +++++++++++++++++++++++++++++++++++ > include/linux/dma-buf-io.h | 92 ++++++++++++ > include/linux/fs.h | 2 + > 4 files changed, 373 insertions(+), 1 deletion(-) > create mode 100644 drivers/dma-buf/dma-buf-io.c > create mode 100644 include/linux/dma-buf-io.h > > diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile > index b25d7550bacf..523731b0f83e 100644 > --- a/drivers/dma-buf/Makefile > +++ b/drivers/dma-buf/Makefile > @@ -1,6 +1,6 @@ > # SPDX-License-Identifier: GPL-2.0-only > obj-y := dma-buf.o dma-fence.o dma-fence-array.o dma-fence-chain.o \ > - dma-fence-unwrap.o dma-resv.o dma-buf-mapping.o > + dma-fence-unwrap.o dma-resv.o dma-buf-mapping.o dma-buf-io.o > obj-$(CONFIG_DMABUF_HEAPS) += dma-heap.o > obj-$(CONFIG_DMABUF_HEAPS) += heaps/ > obj-$(CONFIG_SYNC_FILE) += sync_file.o > diff --git a/drivers/dma-buf/dma-buf-io.c b/drivers/dma-buf/dma-buf-io.c > new file mode 100644 > index 000000000000..24f58f80c45c > --- /dev/null > +++ b/drivers/dma-buf/dma-buf-io.c > @@ -0,0 +1,278 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Common infrastructure for supporing dma-buf in the I/O path. > + * > + * Copyright (C) 2026 Pavel Begunkov <asml.silence(a)gmail.com> > + */ > +#include <linux/dma-buf-io.h> > +#include <linux/dma-resv.h> > + > +struct dma_buf_io_fence { > + struct dma_fence base; > + spinlock_t lock; > +}; > + > +static const char *dma_buf_io_fence_drv_name(struct dma_fence *fence) > +{ > + /* default fence release kfree's the base pointer */ > + BUILD_BUG_ON(offsetof(struct dma_buf_io_fence, base)); > + > + return "dma-buf-io-ctx"; > +} > + > +static const char *dma_buf_io_fence_timeline_name(struct dma_fence *fence) > +{ > + return "dma-buf-io-ctx"; > +} > + > +const struct dma_fence_ops dma_buf_io_fence_ops = { > + .get_driver_name = dma_buf_io_fence_drv_name, > + .get_timeline_name = dma_buf_io_fence_timeline_name, > +}; > + > +static void dma_buf_io_ctx_destroy_work(struct work_struct *work) > +{ > + struct dma_buf_io_ctx *ctx = container_of(work, struct dma_buf_io_ctx, > + release_work); > + > + if (WARN_ON_ONCE(refcount_read(&ctx->refs))) > + return; > + > + ctx->dev_ops->release(ctx); > + dma_buf_put(ctx->dmabuf); > + kfree(ctx); > +} > + > +static void dma_buf_io_map_release_work(struct work_struct *work) > +{ > + struct dma_buf_io_map *map = container_of(work, struct dma_buf_io_map, > + release_work); > + struct dma_buf_io_fence *fence = map->fence; > + struct dma_buf_io_ctx *ctx = map->ctx; > + struct dma_buf *dmabuf = ctx->dmabuf; > + > + /* the release path must wait for fences */ > + if (WARN_ON_ONCE(refcount_read(&ctx->refs) == 0)) > + return; > + > + /* Prevent from destoying the ctx while unmapping */ > + refcount_inc(&ctx->refs); > + > + /* > + * There are no more requests using the map, we can signal the fence. > + * It should be done before taking the resv lock as someone could be > + * waiting for the fence while holding the lock. > + */ > + dma_fence_signal(&fence->base); > + > + dma_resv_lock(dmabuf->resv, NULL); > + ctx->dev_ops->unmap(ctx, map); > + dma_resv_unlock(dmabuf->resv); > + > + dma_fence_put(&fence->base); > + percpu_ref_exit(&map->refs); > + kfree(map); > + > + if (refcount_dec_and_test(&ctx->refs)) { > + /* > + * Destruction needs to wait for I/O and dma fences. Defer it to > + * simplify locking. > + */ > + INIT_WORK(&ctx->release_work, dma_buf_io_ctx_destroy_work); > + queue_work(system_wq, &ctx->release_work); > + } > +} > + > +static void dma_buf_io_map_refs_release(struct percpu_ref *ref) > +{ > + struct dma_buf_io_map *map = container_of(ref, struct dma_buf_io_map, refs); > + > + /* might sleep, use a worker */ > + INIT_WORK(&map->release_work, dma_buf_io_map_release_work); > + queue_work(system_wq, &map->release_work); > +} > + > +int dma_buf_io_init_map(struct dma_buf_io_ctx *ctx, struct dma_buf_io_map *map) > +{ > + struct dma_buf_io_fence *fence = NULL; > + int ret; > + > + fence = kzalloc(sizeof(*fence), GFP_KERNEL); > + if (!fence) > + return -ENOMEM; > + > + ret = percpu_ref_init(&map->refs, dma_buf_io_map_refs_release, 0, GFP_KERNEL); > + if (ret) { > + kfree(fence); > + return ret; > + } > + > + spin_lock_init(&fence->lock); > + dma_fence_init(&fence->base, &dma_buf_io_fence_ops, &fence->lock, > + ctx->fence_ctx, atomic_inc_return(&ctx->fence_seq)); > + map->fence = fence; > + map->ctx = ctx; > + return 0; > +} > +EXPORT_SYMBOL_NS_GPL(dma_buf_io_init_map, "DMA_BUF"); > + > +struct dma_buf_io_map *dma_buf_io_create_map(struct dma_buf_io_ctx *ctx) > +{ > + struct dma_buf *dmabuf = ctx->dmabuf; > + struct dma_buf_io_map *map; > + long ret; > + > +retry: > + /* > + * ->dmabuf_map() will be calling dma_buf_map_attachment(), for which > + * we'll need to wait for fences. Do a bit nicer and try to wait > + * without the resv lock first. > + */ > + ret = dma_resv_wait_timeout(dmabuf->resv, DMA_RESV_USAGE_KERNEL, > + true, MAX_SCHEDULE_TIMEOUT); > + if (!ret) > + ret = -EAGAIN; > + if (ret < 0) > + return ERR_PTR(ret); > + > + ret = dma_resv_lock_interruptible(dmabuf->resv, NULL); > + if (ret) > + return ERR_PTR(ret); > + > + map = dma_buf_io_get_map(ctx); > + if (map) { > + ret = 0; > + goto out; > + } > + > + if (dma_resv_wait_timeout(dmabuf->resv, DMA_RESV_USAGE_KERNEL, > + true, 0) < 0) { > + dma_resv_unlock(dmabuf->resv); > + goto retry; > + } > + > + map = ctx->dev_ops->map(ctx); > + if (IS_ERR(map)) { > + ret = PTR_ERR(map); > + goto out; > + } > + > + if (WARN_ON_ONCE(!map->seg_shift)) > + return ERR_PTR(-EFAULT); > + > + percpu_ref_get(&map->refs); > + rcu_assign_pointer(ctx->map, map); > +out: > + dma_resv_unlock(dmabuf->resv); > + if (ret < 0) > + return ERR_PTR(ret); > + return map; > +} > + > +static void dma_buf_io_drop_map(struct dma_buf_io_ctx *ctx) > +{ > + struct dma_buf *dmabuf = ctx->dmabuf; > + struct dma_buf_io_map *map; > + int ret; > + > + dma_resv_assert_held(dmabuf->resv); > + > + map = rcu_dereference_protected(ctx->map, > + dma_resv_held(dmabuf->resv)); > + if (!map) > + return; > + rcu_assign_pointer(ctx->map, NULL); > + > + ret = dma_resv_reserve_fences(dmabuf->resv, 1); > + if (WARN_ON_ONCE(ret)) { > + struct dma_fence *fence = &map->fence->base; > + > + dma_fence_get(fence); > + percpu_ref_kill(&map->refs); > + dma_fence_wait(fence, false); > + dma_fence_put(fence); > + return; > + } > + > + dma_resv_add_fence(dmabuf->resv, &map->fence->base, > + DMA_RESV_USAGE_KERNEL); > + /* > + * Delay destruction until all inflight requests using the map are > + * gone. It'll also signal the fence then. > + */ > + percpu_ref_kill(&map->refs); > +} > + > +void dma_buf_io_invalidate_mappings(struct dma_buf_io_ctx *ctx) > +{ > + dma_buf_io_drop_map(ctx); > +} > +EXPORT_SYMBOL_NS_GPL(dma_buf_io_invalidate_mappings, "DMA_BUF"); > + > +static void dma_buf_io_ctx_release_work(struct work_struct *work) > +{ > + struct dma_buf_io_ctx *ctx = container_of(work, struct dma_buf_io_ctx, > + release_work); > + struct dma_buf *dmabuf = ctx->dmabuf; > + long ret; > + > + dma_resv_lock(dmabuf->resv, NULL); > + /* Remove the last map, there should be no new ones going forward. */ > + dma_buf_io_drop_map(ctx); > + dma_resv_unlock(dmabuf->resv); > + > + /* Wait until all maps are destroyed. */ > + ret = dma_resv_wait_timeout(dmabuf->resv, DMA_RESV_USAGE_KERNEL, > + false, MAX_SCHEDULE_TIMEOUT); > + > + if (WARN_ON_ONCE(ret <= 0)) > + return; > + if (WARN_ON_ONCE(rcu_dereference_protected(ctx->map, true))) > + return; > + > + if (refcount_dec_and_test(&ctx->refs)) > + dma_buf_io_ctx_destroy_work(&ctx->release_work); > +} > + > +void dma_buf_io_ctx_release(struct dma_buf_io_ctx *ctx) > +{ > + /* > + * Destruction needs to wait for I/O and dma fences. Defer it to > + * simplify locking. > + */ > + INIT_WORK(&ctx->release_work, dma_buf_io_ctx_release_work); > + queue_work(system_wq, &ctx->release_work); > +} > + > +int dma_buf_io_ctx_create(struct file *file, > + struct dma_buf_io_ctx *ctx, > + struct dma_buf *dmabuf, > + enum dma_data_direction dir) > +{ > + int ret; > + > + if (!file->f_op->init_dma_buf_io_ctx) > + return -EOPNOTSUPP; > + > + memset(ctx, 0, sizeof(*ctx)); > + ctx->fence_ctx = dma_fence_context_alloc(1); > + ctx->dir = dir; > + ctx->dmabuf = dmabuf; > + refcount_set(&ctx->refs, 1); > + get_dma_buf(dmabuf); > + > + ret = file->f_op->init_dma_buf_io_ctx(file, ctx); > + if (ret) { > + memset(ctx, 0, sizeof(*ctx)); > + dma_buf_put(dmabuf); > + return ret; > + } > + > + if (WARN_ON_ONCE(!ctx->dev_ops || > + !ctx->dev_ops->map || > + !ctx->dev_ops->unmap || > + !ctx->dev_ops->release)) > + return -EINVAL; > + > + return ret; > +} > diff --git a/include/linux/dma-buf-io.h b/include/linux/dma-buf-io.h > new file mode 100644 > index 000000000000..f31c7375ae91 > --- /dev/null > +++ b/include/linux/dma-buf-io.h > @@ -0,0 +1,92 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef __DMA_BUF_IO_H__ > +#define __DMA_BUF_IO_H__ > + > +#include <linux/dma-buf.h> > + > +struct dma_buf_io_fence; > +struct dma_buf_io_ctx; > +struct dma_buf_io_map; > + > +struct dma_buf_io_ops { > + /* > + * Create a new map for the given ctx. Called with the reservation > + * lock held. > + */ > + struct dma_buf_io_map *(*map)(struct dma_buf_io_ctx *ctx); > + > + /* > + * Clean up device specific parts of the @map. Called with the > + * reservation lock held. > + */ > + void (*unmap)(struct dma_buf_io_ctx *ctx, struct dma_buf_io_map *map); > + > + /* > + * The user tries to destroy the ctx. Release all device specific > + * parts of the token. > + */ > + void (*release)(struct dma_buf_io_ctx *); > +}; > + > +struct dma_buf_io_map { > + /* > + * Counts attached requests and other users. Device specific unmapping > + * is deferred until all refs are dropped. > + */ > + struct percpu_ref refs; > + unsigned seg_shift; Can you add a big fat comment explaining how seg_shift works here? I'm looking at the later patch using it for splitting and am very confused about it.

2 weeks, 3 days

Re: [PATCH v5 06/16] block: introduce bio_iov_iter_set()

by Christoph Hellwig

Looks good: Reviewed-by: Christoph Hellwig <hch(a)lst.de>

2 weeks, 3 days

Re: [PATCH] drm/gem: Move pages_to_sg helper into drm_gem.c

by Christian König

On 7/24/26 14:08, Adrián Larumbe wrote: > None of the semantics of the function tell of it being a PRIME-exclusive > entry point. In fact, most drivers seem to be using it to translate a list > of pages into an sg table that can be used for GPU mapping later on, rather > than just for sharing an object's pages with another driver. > > Move it across files and rename accordingly. > > Signed-off-by: Adrián Larumbe <adrian.larumbe(a)collabora.com> > --- > drm_prime_pages_to_sg() has no real dependency on PRIME/dma-buf interfaces. > It is a generic helper that converts a page array into a scatter/gather > table via dma_map_sg_attrs. Nothing in its implementation touches struct > dma_buf or import/export logic. It is correct that this helper is not DMA-buf dependent, but DMA-buf should be the only case when a DRM driver needs to convert an array of pages into an SG table. The background is that we want to discourage people from using SG tables because it was a rather bad design choice to have pages mangled with the DMA addresses in one structure in the first place. So question is why do you want to do this? Regards, Christian. > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 6 ++--- > drivers/gpu/drm/drm_gem.c | 35 ++++++++++++++++++++++++++ > drivers/gpu/drm/drm_gem_shmem_helper.c | 2 +- > drivers/gpu/drm/drm_prime.c | 38 ----------------------------- > drivers/gpu/drm/etnaviv/etnaviv_gem.c | 3 +-- > drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c | 3 ++- > drivers/gpu/drm/loongson/lsdc_gem.c | 3 +-- > drivers/gpu/drm/msm/msm_gem.c | 2 +- > drivers/gpu/drm/msm/msm_gem_prime.c | 2 +- > drivers/gpu/drm/nouveau/nouveau_prime.c | 4 +-- > drivers/gpu/drm/panthor/panthor_gem.c | 6 ++--- > drivers/gpu/drm/radeon/radeon_prime.c | 5 ++-- > drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 6 ++--- > drivers/gpu/drm/tegra/gem.c | 4 +-- > drivers/gpu/drm/vmwgfx/vmwgfx_gem.c | 4 +-- > drivers/gpu/drm/xe/xe_dma_buf.c | 6 ++--- > drivers/gpu/drm/xen/xen_drm_front_gem.c | 2 +- > include/drm/drm_gem.h | 5 +++- > include/drm/drm_prime.h | 2 -- > 19 files changed, 68 insertions(+), 70 deletions(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c > index b33c300e26e2..c9a98aec7eb6 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c > @@ -203,9 +203,9 @@ static struct sg_table *amdgpu_dma_buf_map(struct dma_buf_attachment *attach, > > switch (bo->tbo.resource->mem_type) { > case TTM_PL_TT: > - sgt = drm_prime_pages_to_sg(obj->dev, > - bo->tbo.ttm->pages, > - bo->tbo.ttm->num_pages); > + sgt = drm_pages_to_sg(obj->dev, > + bo->tbo.ttm->pages, > + bo->tbo.ttm->num_pages); > if (IS_ERR(sgt)) > return sgt; > > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c > index 018df97d590d..22c8a3b5f667 100644 > --- a/drivers/gpu/drm/drm_gem.c > +++ b/drivers/gpu/drm/drm_gem.c > @@ -780,6 +780,41 @@ void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages, > } > EXPORT_SYMBOL(drm_gem_put_pages); > > +/** > + * drm_pages_to_sg - converts a page array into an sg list > + * @dev: DRM device > + * @pages: pointer to the array of page pointers to convert > + * @nr_pages: length of the page vector > + * > + * This helper creates an sg table object from a set of pages. > + * This is useful for implementing &drm_gem_object_funcs.get_sg_table. > + */ > +struct sg_table *drm_pages_to_sg(struct drm_device *dev, > + struct page **pages, unsigned int nr_pages) > +{ > + struct sg_table *sg; > + size_t max_segment = 0; > + int err; > + > + sg = kmalloc_obj(struct sg_table); > + if (!sg) > + return ERR_PTR(-ENOMEM); > + > + if (dev) > + max_segment = dma_max_mapping_size(drm_dev_dma_dev(dev)); > + if (max_segment == 0) > + max_segment = UINT_MAX; > + err = sg_alloc_table_from_pages_segment(sg, pages, nr_pages, 0, > + (unsigned long)nr_pages << PAGE_SHIFT, > + max_segment, GFP_KERNEL); > + if (err) { > + kfree(sg); > + sg = ERR_PTR(err); > + } > + return sg; > +} > +EXPORT_SYMBOL(drm_pages_to_sg); > + > static int objects_lookup(struct drm_file *filp, u32 *handle, int count, > struct drm_gem_object **objs) > { > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index 22ec52e2ffb8..144d088a477f 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -825,7 +825,7 @@ struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem) > > drm_WARN_ON(obj->dev, drm_gem_is_imported(obj)); > > - return drm_prime_pages_to_sg(obj->dev, shmem->pages, obj->size >> PAGE_SHIFT); > + return drm_pages_to_sg(obj->dev, shmem->pages, obj->size >> PAGE_SHIFT); > } > EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table); > > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > index 9b44c78cd77f..54539a8929c1 100644 > --- a/drivers/gpu/drm/drm_prime.c > +++ b/drivers/gpu/drm/drm_prime.c > @@ -835,44 +835,6 @@ static const struct dma_buf_ops drm_gem_prime_dmabuf_ops = { > .vunmap = drm_gem_dmabuf_vunmap, > }; > > -/** > - * drm_prime_pages_to_sg - converts a page array into an sg list > - * @dev: DRM device > - * @pages: pointer to the array of page pointers to convert > - * @nr_pages: length of the page vector > - * > - * This helper creates an sg table object from a set of pages > - * the driver is responsible for mapping the pages into the > - * importers address space for use with dma_buf itself. > - * > - * This is useful for implementing &drm_gem_object_funcs.get_sg_table. > - */ > -struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev, > - struct page **pages, unsigned int nr_pages) > -{ > - struct sg_table *sg; > - size_t max_segment = 0; > - int err; > - > - sg = kmalloc_obj(struct sg_table); > - if (!sg) > - return ERR_PTR(-ENOMEM); > - > - if (dev) > - max_segment = dma_max_mapping_size(drm_dev_dma_dev(dev)); > - if (max_segment == 0) > - max_segment = UINT_MAX; > - err = sg_alloc_table_from_pages_segment(sg, pages, nr_pages, 0, > - (unsigned long)nr_pages << PAGE_SHIFT, > - max_segment, GFP_KERNEL); > - if (err) { > - kfree(sg); > - sg = ERR_PTR(err); > - } > - return sg; > -} > -EXPORT_SYMBOL(drm_prime_pages_to_sg); > - > /** > * drm_prime_get_contiguous_size - returns the contiguous size of the buffer > * @sgt: sg_table describing the buffer to check > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c > index b0436a1e103f..a8e8614f8210 100644 > --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c > @@ -3,7 +3,6 @@ > * Copyright (C) 2015-2018 Etnaviv Project > */ > > -#include <drm/drm_prime.h> > #include <drm/drm_print.h> > #include <linux/dma-mapping.h> > #include <linux/shmem_fs.h> > @@ -104,7 +103,7 @@ struct page **etnaviv_gem_get_pages(struct etnaviv_gem_object *etnaviv_obj) > unsigned int npages = etnaviv_obj->base.size >> PAGE_SHIFT; > struct sg_table *sgt; > > - sgt = drm_prime_pages_to_sg(dev, etnaviv_obj->pages, npages); > + sgt = drm_pages_to_sg(dev, etnaviv_obj->pages, npages); > if (IS_ERR(sgt)) { > dev_err(dev->dev, "failed to allocate sgt: %ld\n", > PTR_ERR(sgt)); > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c > index 6757ae6ec304..f44484325ddb 100644 > --- a/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c > @@ -3,6 +3,7 @@ > * Copyright (C) 2014-2018 Etnaviv Project > */ > > +#include <drm/drm_gem.h> > #include <drm/drm_prime.h> > #include <linux/dma-buf.h> > #include <linux/module.h> > @@ -22,7 +23,7 @@ struct sg_table *etnaviv_gem_prime_get_sg_table(struct drm_gem_object *obj) > if (WARN_ON(!etnaviv_obj->pages)) /* should have already pinned! */ > return ERR_PTR(-EINVAL); > > - return drm_prime_pages_to_sg(obj->dev, etnaviv_obj->pages, npages); > + return drm_pages_to_sg(obj->dev, etnaviv_obj->pages, npages); > } > > int etnaviv_gem_prime_vmap(struct drm_gem_object *obj, struct iosys_map *map) > diff --git a/drivers/gpu/drm/loongson/lsdc_gem.c b/drivers/gpu/drm/loongson/lsdc_gem.c > index 2fb03487c983..37160228244c 100644 > --- a/drivers/gpu/drm/loongson/lsdc_gem.c > +++ b/drivers/gpu/drm/loongson/lsdc_gem.c > @@ -9,7 +9,6 @@ > #include <drm/drm_dumb_buffers.h> > #include <drm/drm_file.h> > #include <drm/drm_gem.h> > -#include <drm/drm_prime.h> > #include <drm/drm_print.h> > > #include "lsdc_drv.h" > @@ -51,7 +50,7 @@ static struct sg_table *lsdc_gem_prime_get_sg_table(struct drm_gem_object *obj) > return ERR_PTR(-ENOMEM); > } > > - return drm_prime_pages_to_sg(obj->dev, tt->pages, tt->num_pages); > + return drm_pages_to_sg(obj->dev, tt->pages, tt->num_pages); > } > > static void lsdc_gem_object_free(struct drm_gem_object *obj) > diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c > index efd3d3c9a449..7e3418290c22 100644 > --- a/drivers/gpu/drm/msm/msm_gem.c > +++ b/drivers/gpu/drm/msm/msm_gem.c > @@ -207,7 +207,7 @@ static struct page **get_pages(struct drm_gem_object *obj) > > msm_obj->pages = p; > > - msm_obj->sgt = drm_prime_pages_to_sg(obj->dev, p, npages); > + msm_obj->sgt = drm_pages_to_sg(obj->dev, p, npages); > if (IS_ERR(msm_obj->sgt)) { > void *ptr = ERR_CAST(msm_obj->sgt); > > diff --git a/drivers/gpu/drm/msm/msm_gem_prime.c b/drivers/gpu/drm/msm/msm_gem_prime.c > index 036d34c674d9..d25393a9e549 100644 > --- a/drivers/gpu/drm/msm/msm_gem_prime.c > +++ b/drivers/gpu/drm/msm/msm_gem_prime.c > @@ -23,7 +23,7 @@ struct sg_table *msm_gem_prime_get_sg_table(struct drm_gem_object *obj) > if (WARN_ON(!msm_obj->pages)) /* should have already pinned! */ > return ERR_PTR(-ENOMEM); > > - return drm_prime_pages_to_sg(obj->dev, msm_obj->pages, npages); > + return drm_pages_to_sg(obj->dev, msm_obj->pages, npages); > } > > int msm_gem_prime_vmap(struct drm_gem_object *obj, struct iosys_map *map) > diff --git a/drivers/gpu/drm/nouveau/nouveau_prime.c b/drivers/gpu/drm/nouveau/nouveau_prime.c > index caab60fc62f6..b95f2f07df74 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_prime.c > +++ b/drivers/gpu/drm/nouveau/nouveau_prime.c > @@ -32,8 +32,8 @@ struct sg_table *nouveau_gem_prime_get_sg_table(struct drm_gem_object *obj) > { > struct nouveau_bo *nvbo = nouveau_gem_object(obj); > > - return drm_prime_pages_to_sg(obj->dev, nvbo->bo.ttm->pages, > - nvbo->bo.ttm->num_pages); > + return drm_pages_to_sg(obj->dev, nvbo->bo.ttm->pages, > + nvbo->bo.ttm->num_pages); > } > > struct drm_gem_object *nouveau_gem_prime_import_sg_table(struct drm_device *dev, > diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c > index 9855df738194..ec530d254fa4 100644 > --- a/drivers/gpu/drm/panthor/panthor_gem.c > +++ b/drivers/gpu/drm/panthor/panthor_gem.c > @@ -321,8 +321,8 @@ panthor_gem_dev_map_get_sgt_locked(struct panthor_gem_object *bo) > if (ret) > return ERR_PTR(ret); > > - sgt = drm_prime_pages_to_sg(bo->base.dev, bo->backing.pages, > - bo->base.size >> PAGE_SHIFT); > + sgt = drm_pages_to_sg(bo->base.dev, bo->backing.pages, > + bo->base.size >> PAGE_SHIFT); > if (IS_ERR(sgt)) > return sgt; > > @@ -702,7 +702,7 @@ static struct sg_table *panthor_gem_get_sg_table(struct drm_gem_object *obj) > drm_WARN_ON_ONCE(obj->dev, !bo->backing.pages); > drm_WARN_ON_ONCE(obj->dev, !refcount_read(&bo->backing.pin_count)); > > - return drm_prime_pages_to_sg(obj->dev, bo->backing.pages, obj->size >> PAGE_SHIFT); > + return drm_pages_to_sg(obj->dev, bo->backing.pages, obj->size >> PAGE_SHIFT); > } > > static int panthor_gem_vmap_locked(struct drm_gem_object *obj, > diff --git a/drivers/gpu/drm/radeon/radeon_prime.c b/drivers/gpu/drm/radeon/radeon_prime.c > index a77881f035e7..4cfc4282a59c 100644 > --- a/drivers/gpu/drm/radeon/radeon_prime.c > +++ b/drivers/gpu/drm/radeon/radeon_prime.c > @@ -26,6 +26,7 @@ > > #include <linux/dma-buf.h> > > +#include <drm/drm_gem.h> > #include <drm/drm_prime.h> > #include <drm/radeon_drm.h> > > @@ -38,8 +39,8 @@ struct sg_table *radeon_gem_prime_get_sg_table(struct drm_gem_object *obj) > { > struct radeon_bo *bo = gem_to_radeon_bo(obj); > > - return drm_prime_pages_to_sg(obj->dev, bo->tbo.ttm->pages, > - bo->tbo.ttm->num_pages); > + return drm_pages_to_sg(obj->dev, bo->tbo.ttm->pages, > + bo->tbo.ttm->num_pages); > } > > struct drm_gem_object *radeon_gem_prime_import_sg_table(struct drm_device *dev, > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > index b188539dca0b..7897da0becf4 100644 > --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > @@ -89,8 +89,8 @@ static int rockchip_gem_get_pages(struct rockchip_gem_object *rk_obj) > > rk_obj->num_pages = rk_obj->base.size >> PAGE_SHIFT; > > - rk_obj->sgt = drm_prime_pages_to_sg(rk_obj->base.dev, > - rk_obj->pages, rk_obj->num_pages); > + rk_obj->sgt = drm_pages_to_sg(rk_obj->base.dev, > + rk_obj->pages, rk_obj->num_pages); > if (IS_ERR(rk_obj->sgt)) { > ret = PTR_ERR(rk_obj->sgt); > goto err_put_pages; > @@ -432,7 +432,7 @@ struct sg_table *rockchip_gem_prime_get_sg_table(struct drm_gem_object *obj) > int ret; > > if (rk_obj->pages) > - return drm_prime_pages_to_sg(obj->dev, rk_obj->pages, rk_obj->num_pages); > + return drm_pages_to_sg(obj->dev, rk_obj->pages, rk_obj->num_pages); > > sgt = kzalloc_obj(*sgt); > if (!sgt) > diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c > index 436394e04812..701af672b4e5 100644 > --- a/drivers/gpu/drm/tegra/gem.c > +++ b/drivers/gpu/drm/tegra/gem.c > @@ -17,7 +17,7 @@ > > #include <drm/drm_drv.h> > #include <drm/drm_dumb_buffers.h> > -#include <drm/drm_prime.h> > +#include <drm/drm_gem.h> > > #include "drm.h" > #include "gem.h" > @@ -352,7 +352,7 @@ static int tegra_bo_get_pages(struct drm_device *drm, struct tegra_bo *bo) > > bo->num_pages = bo->gem.size >> PAGE_SHIFT; > > - bo->sgt = drm_prime_pages_to_sg(bo->gem.dev, bo->pages, bo->num_pages); > + bo->sgt = drm_pages_to_sg(bo->gem.dev, bo->pages, bo->num_pages); > if (IS_ERR(bo->sgt)) { > err = PTR_ERR(bo->sgt); > goto put_pages; > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c b/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c > index 39f8c46550c2..c9e7f2e3668c 100644 > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c > @@ -28,7 +28,7 @@ > #include "vmwgfx_bo.h" > #include "vmwgfx_drv.h" > > -#include "drm/drm_prime.h" > +#include "drm/drm_gem.h" > #include "drm/drm_gem_ttm_helper.h" > > #include <linux/debugfs.h> > @@ -76,7 +76,7 @@ static struct sg_table *vmw_gem_object_get_sg_table(struct drm_gem_object *obj) > if (vmw_tt->vsgt.sgt) > return vmw_tt->vsgt.sgt; > > - return drm_prime_pages_to_sg(obj->dev, vmw_tt->dma_ttm.pages, vmw_tt->dma_ttm.num_pages); > + return drm_pages_to_sg(obj->dev, vmw_tt->dma_ttm.pages, vmw_tt->dma_ttm.num_pages); > } > > static int vmw_gem_vmap(struct drm_gem_object *obj, struct iosys_map *map) > diff --git a/drivers/gpu/drm/xe/xe_dma_buf.c b/drivers/gpu/drm/xe/xe_dma_buf.c > index 8a920e58245c..f0fe80706b79 100644 > --- a/drivers/gpu/drm/xe/xe_dma_buf.c > +++ b/drivers/gpu/drm/xe/xe_dma_buf.c > @@ -118,9 +118,9 @@ static struct sg_table *xe_dma_buf_map(struct dma_buf_attachment *attach, > > switch (bo->ttm.resource->mem_type) { > case XE_PL_TT: > - sgt = drm_prime_pages_to_sg(obj->dev, > - bo->ttm.ttm->pages, > - obj->size >> PAGE_SHIFT); > + sgt = drm_pages_to_sg(obj->dev, > + bo->ttm.ttm->pages, > + obj->size >> PAGE_SHIFT); > if (IS_ERR(sgt)) > return sgt; > > diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c b/drivers/gpu/drm/xen/xen_drm_front_gem.c > index eec4c1da3f9e..a4a7c7f2c91c 100644 > --- a/drivers/gpu/drm/xen/xen_drm_front_gem.c > +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c > @@ -236,7 +236,7 @@ struct sg_table *xen_drm_front_gem_get_sg_table(struct drm_gem_object *gem_obj) > if (!xen_obj->pages) > return ERR_PTR(-ENOMEM); > > - return drm_prime_pages_to_sg(gem_obj->dev, > + return drm_pages_to_sg(gem_obj->dev, > xen_obj->pages, xen_obj->num_pages); > } > > diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h > index 885244e375d3..7b9cc6335689 100644 > --- a/include/drm/drm_gem.h > +++ b/include/drm/drm_gem.h > @@ -155,7 +155,7 @@ struct drm_gem_object_funcs { > * here cannot be used for sg tables pointing at driver private memory > * ranges. > * > - * See also drm_prime_pages_to_sg(). > + * See also drm_pages_to_sg(). > */ > struct sg_table *(*get_sg_table)(struct drm_gem_object *obj); > > @@ -589,6 +589,9 @@ struct page **drm_gem_get_pages(struct drm_gem_object *obj); > void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages, > bool dirty, bool accessed); > > +struct sg_table *drm_pages_to_sg(struct drm_device *dev, > + struct page **pages, unsigned int nr_pages); > + > void drm_gem_lock(struct drm_gem_object *obj); > void drm_gem_unlock(struct drm_gem_object *obj); > > diff --git a/include/drm/drm_prime.h b/include/drm/drm_prime.h > index f50f862f0d8b..603e16a40ae7 100644 > --- a/include/drm/drm_prime.h > +++ b/include/drm/drm_prime.h > @@ -92,8 +92,6 @@ void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct iosys_map *map); > int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma); > int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma); > > -struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev, > - struct page **pages, unsigned int nr_pages); > struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj, > int flags); > > > --- > base-commit: 48dd37d1fef33fbf42f1d6887c61e242fd21d00d > change-id: 20260724-get_pages-e2e91c53eaa3 > > Best regards, > -- > Adrián Larumbe <adrian.larumbe(a)collabora.com> >

2 weeks, 4 days

Re: [PATCH v2] dma-buf/udmabuf: Disable the size limit by default

by Kasireddy, Vivek

> Subject: Re: [PATCH v2] dma-buf/udmabuf: Disable the size limit by > default > > On 28.07.26 22:20, Kasireddy, Vivek wrote: > > Hi Robert, > > > >> Subject: [PATCH v2] dma-buf/udmabuf: Disable the size limit by > default > >> > >> As udmabuf increasingly enjoys popularity - being used in projects > like > >> libcamera, Gstreamer, Mesa, KWin and Weston - users more > frequently > >> encounter cases where the current default size limit of 64MB is too > low. > >> Examples include allocating video buffers at a 8K resolution - and > even > >> 4K > >> is affected when using non-subsampled video formats and high bit > >> depths. > >> > >> In its current form the size limit for individual buffers does not seem > to > >> provide any additional level of protection - such as limiting the > amount > >> of > >> memory a process can pin - as the later can just allocate multiple > >> buffers. > >> If additional guardrails are desired, they would likely require some > kind > >> accounting not limited to individual buffers. > >> > >> Therefor let's disable the size limit by default by setting it to the > >> maximal possible value, INT_MAX. > >> > >> Signed-off-by: Robert Mader <robert.mader(a)collabora.com> > >> > >> --- > >> > >> Changes in V2: > >> - Use INT_MAX instead of 0 in order to not change behavior > otherwise. > >> > >> See > >> https://lore.kernel.org/dri-devel/20260711144814.8205-1- > >> robert.mader(a)collabora.com/ > >> for a previous attempt to make the value configurable via kconfig - > and > >> in particular > >> https://lore.kernel.org/dri-devel/6764ca6f-b4d8-4baa-9d27- > >> 2ca867ac2d41(a)amd.com/ > >> for the suggestion and discussion to remove the default limit. > >> --- > >> drivers/dma-buf/udmabuf.c | 4 ++-- > >> 1 file changed, 2 insertions(+), 2 deletions(-) > >> > >> diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c > >> index bced421c0d65..639e93704924 100644 > >> --- a/drivers/dma-buf/udmabuf.c > >> +++ b/drivers/dma-buf/udmabuf.c > >> @@ -20,9 +20,9 @@ static int list_limit = 1024; > >> module_param(list_limit, int, 0644); > >> MODULE_PARM_DESC(list_limit, "udmabuf_create_list->count limit. > >> Default is 1024."); > >> > >> -static int size_limit_mb = 64; > >> +static int size_limit_mb = INT_MAX; > >> module_param(size_limit_mb, int, 0644); > >> -MODULE_PARM_DESC(size_limit_mb, "Max size of a dmabuf, in > >> megabytes. Default is 64."); > >> +MODULE_PARM_DESC(size_limit_mb, "Max size of a dmabuf, in > >> megabytes. Default is INT_MAX."); > > Acked-by: Vivek Kasireddy <vivek.kasireddy(a)intel.com> > > > > If there are no further concerns/questions from anyone, I'll push it to > > drm-misc-next soon. > > FTR., we already have a first duplicate :P > > https://lore.kernel.org/dri-devel/20260803144120.11524-1- > xaver.hugl(a)kde.org/ Yeah, looks like this change seems to be desirable in many use-cases. I have pushed it to drm-misc-next today. Thanks, Vivek > > > > > Thanks, > > Vivek > >> struct udmabuf { > >> pgoff_t pagecount; > >> -- > >> 2.55.0 > > -- > Robert Mader > Consultant Software Developer > > Collabora Ltd. > Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK > Registered in England & Wales, no. 5513718

2 weeks, 4 days

[PATCH v3 0/2] drm/drm_crtc: dma_fence_ops fixes

by André Draszik

Hi, These patches fix two issues in the drm/drm_crtc driver. Initially I was hitting the BUG_ON() in a scenario as explained in the commit message of what is now the second patch in this series. After posting, sashiko.dev noticed another issue, that was previously masked by the now-removed BUG_ON(). Since we can't have a loud BUG() be replaced with silent data corruption or worse, I've also added a patch to address this issue highlighted by sashiko.dev. I believe its observation and analysis to be correct. Cheers, Andre' Signed-off-by: André Draszik <andre.draszik(a)linaro.org> --- Changes in v3: - Philipp: - patch 1: update kerneldoc, add Fixes: - patch 2: shorten commit message - explicitly Cc: stable - collect tag - Link to v2: https://lore.kernel.org/r/20260708-linux-drm_crtc_fix2-v2-0-cf72be75d75a@li… Changes in v2: - add new patch 1 to address sashiko observation - original patch 1 becomes patch 2 - patch 2: - don't turn fence_to_crtc() into macro (Jani, Philipp) - update commit message to include reference to deprecated use of BUG - Link to v1: https://lore.kernel.org/r/20260618-linux-drm_crtc_fix2-v1-1-c03e77b36f34@li… --- André Draszik (2): drm/drm_crtc: ensure dma_fence_ops remain valid during device unbind drm/drm_crtc: fix race with dma_fence_signal() in ::get_driver_name() drivers/gpu/drm/drm_crtc.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) --- base-commit: 0718283ab28bc3907e10b61a6b4be6fefa1cbb2f change-id: 20260618-linux-drm_crtc_fix2-23a7c354a412 Best regards, -- André Draszik <andre.draszik(a)linaro.org>

2 weeks, 5 days

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