diff --git a/Documentation/driver-api/pci/p2pdma.rst b/Documentation/driver-api/pci/p2pdma.rst index d0b241628cf1..280673b50350 100644 --- a/Documentation/driver-api/pci/p2pdma.rst +++ b/Documentation/driver-api/pci/p2pdma.rst @@ -9,22 +9,48 @@ between two devices on the bus. This type of transaction is henceforth called Peer-to-Peer (or P2P). However, there are a number of issues that make P2P transactions tricky to do in a perfectly safe way. -One of the biggest issues is that PCI doesn't require forwarding -transactions between hierarchy domains, and in PCIe, each Root Port -defines a separate hierarchy domain. To make things worse, there is no -simple way to determine if a given Root Complex supports this or not. -(See PCIe r4.0, sec 1.3.1). Therefore, as of this writing, the kernel -only supports doing P2P when the endpoints involved are all behind the -same PCI bridge, as such devices are all in the same PCI hierarchy -domain, and the spec guarantees that all transactions within the -hierarchy will be routable, but it does not require routing -between hierarchies. +For PCIe the routing of Transaction Layer Packets (TLPs) is well-defined up +until they reach a host bridge or root port. If the path includes PCIe switches +then based on the ACS settings the transaction can route entirely within +the PCIe hierarchy and never reach the root port. The kernel will evaluate +the PCIe topology and always permit P2P in these well-defined cases. -The second issue is that to make use of existing interfaces in Linux, -memory that is used for P2P transactions needs to be backed by struct -pages. However, PCI BARs are not typically cache coherent so there are -a few corner case gotchas with these pages so developers need to -be careful about what they do with them. +However, if the P2P transaction reaches the host bridge then it might have to +hairpin back out the same root port, be routed inside the CPU SOC to another +PCIe root port, or routed internally to the SOC. + +The PCIe specification doesn't define the forwarding of transactions between +hierarchy domains and kernel defaults to blocking such routing. There is an +allow list to allow detecting known-good HW, in which case P2P between any +two PCIe devices will be permitted. + +Since P2P inherently is doing transactions between two devices it requires two +drivers to be co-operating inside the kernel. The providing driver has to convey +its MMIO to the consuming driver. To meet the driver model lifecycle rules the +MMIO must have all DMA mapping removed, all CPU accesses prevented, all page +table mappings undone before the providing driver completes remove(). + +This requires the providing and consuming driver to actively work together to +guarantee that the consuming driver has stopped using the MMIO during a removal +cycle. This is done by either a synchronous invalidation shutdown or waiting +for all usage refcounts to reach zero. + +At the lowest level the P2P subsystem offers a naked struct p2p_provider that +delegates lifecycle management to the providing driver. It is expected that +drivers using this option will wrap their MMIO memory in DMABUF and use DMABUF +to provide an invalidation shutdown. These MMIO addresess have no struct page, and +if used with mmap() must create special PTEs. As such there are very few +kernel uAPIs that can accept pointers to them; in particular they cannot be used +with read()/write(), including O_DIRECT. + +Building on this, the subsystem offers a layer to wrap the MMIO in a ZONE_DEVICE +pgmap of MEMORY_DEVICE_PCI_P2PDMA to create struct pages. The lifecycle of +pgmap ensures that when the pgmap is destroyed all other drivers have stopped +using the MMIO. This option works with O_DIRECT flows, in some cases, if the +underlying subsystem supports handling MEMORY_DEVICE_PCI_P2PDMA through +FOLL_PCI_P2PDMA. The use of FOLL_LONGTERM is prevented. As this relies on pgmap +it also relies on architecture support along with alignment and minimum size +limitations. Driver Writer's Guide @@ -114,14 +140,39 @@ allocating scatter-gather lists with P2P memory. Struct Page Caveats ------------------- -Driver writers should be very careful about not passing these special -struct pages to code that isn't prepared for it. At this time, the kernel -interfaces do not have any checks for ensuring this. This obviously -precludes passing these pages to userspace. +While the MEMORY_DEVICE_PCI_P2PDMA pages can be installed in VMAs, +pin_user_pages() and related will not return them unless FOLL_PCI_P2PDMA is set. -P2P memory is also technically IO memory but should never have any side -effects behind it. Thus, the order of loads and stores should not be important -and ioreadX(), iowriteX() and friends should not be necessary. +The MEMORY_DEVICE_PCI_P2PDMA pages require care to support in the kernel. The +KVA is still MMIO and must still be accessed through the normal +readX()/writeX()/etc helpers. Direct CPU access (e.g. memcpy) is forbidden, just +like any other MMIO mapping. While this will actually work on some +architectures, others will experience corruption or just crash in the kernel. +Supporting FOLL_PCI_P2PDMA in a subsystem requires scrubbing it to ensure no CPU +access happens. + + +Usage With DMABUF +================= + +DMABUF provides an alternative to the above struct page-based +client/provider/orchestrator system and should be used when struct page +doesn't exist. In this mode the exporting driver will wrap +some of its MMIO in a DMABUF and give the DMABUF FD to userspace. + +Userspace can then pass the FD to an importing driver which will ask the +exporting driver to map it to the importer. + +In this case the initiator and target pci_devices are known and the P2P subsystem +is used to determine the mapping type. The phys_addr_t-based DMA API is used to +establish the dma_addr_t. + +Lifecycle is controlled by DMABUF move_notify(). When the exporting driver wants +to remove() it must deliver an invalidation shutdown to all DMABUF importing +drivers through move_notify() and synchronously DMA unmap all the MMIO. + +No importing driver can continue to have a DMA map to the MMIO after the +exporting driver has destroyed its p2p_provider. P2P DMA Support Library diff --git a/block/blk-mq-dma.c b/block/blk-mq-dma.c index 449950029872..a1b623744b2f 100644 --- a/block/blk-mq-dma.c +++ b/block/blk-mq-dma.c @@ -85,7 +85,7 @@ static inline bool blk_can_dma_map_iova(struct request *req, static bool blk_dma_map_bus(struct blk_dma_iter *iter, struct phys_vec *vec) { - iter->addr = pci_p2pdma_bus_addr_map(&iter->p2pdma, vec->paddr); + iter->addr = pci_p2pdma_bus_addr_map(iter->p2pdma.mem, vec->paddr); iter->len = vec->len; return true; } diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile index 70ec901edf2c..2008fb7481b3 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-fence-unwrap.o dma-resv.o dma-buf-mapping.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-mapping.c b/drivers/dma-buf/dma-buf-mapping.c new file mode 100644 index 000000000000..b4819811a64a --- /dev/null +++ b/drivers/dma-buf/dma-buf-mapping.c @@ -0,0 +1,248 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * DMA BUF Mapping Helpers + * + */ +#include +#include + +static struct scatterlist *fill_sg_entry(struct scatterlist *sgl, size_t length, + dma_addr_t addr) +{ + unsigned int len, nents; + int i; + + nents = DIV_ROUND_UP(length, UINT_MAX); + for (i = 0; i < nents; i++) { + len = min_t(size_t, length, UINT_MAX); + length -= len; + /* + * DMABUF abuses scatterlist to create a scatterlist + * that does not have any CPU list, only the DMA list. + * Always set the page related values to NULL to ensure + * importers can't use it. The phys_addr based DMA API + * does not require the CPU list for mapping or unmapping. + */ + sg_set_page(sgl, NULL, 0, 0); + sg_dma_address(sgl) = addr + i * UINT_MAX; + sg_dma_len(sgl) = len; + sgl = sg_next(sgl); + } + + return sgl; +} + +static unsigned int calc_sg_nents(struct dma_iova_state *state, + struct dma_buf_phys_vec *phys_vec, + size_t nr_ranges, size_t size) +{ + unsigned int nents = 0; + size_t i; + + if (!state || !dma_use_iova(state)) { + for (i = 0; i < nr_ranges; i++) + nents += DIV_ROUND_UP(phys_vec[i].len, UINT_MAX); + } else { + /* + * In IOVA case, there is only one SG entry which spans + * for whole IOVA address space, but we need to make sure + * that it fits sg->length, maybe we need more. + */ + nents = DIV_ROUND_UP(size, UINT_MAX); + } + + return nents; +} + +/** + * struct dma_buf_dma - holds DMA mapping information + * @sgt: Scatter-gather table + * @state: DMA IOVA state relevant in IOMMU-based DMA + * @size: Total size of DMA transfer + */ +struct dma_buf_dma { + struct sg_table sgt; + struct dma_iova_state *state; + size_t size; +}; + +/** + * dma_buf_phys_vec_to_sgt - Returns the scatterlist table of the attachment + * from arrays of physical vectors. This funciton is intended for MMIO memory + * only. + * @attach: [in] attachment whose scatterlist is to be returned + * @provider: [in] p2pdma provider + * @phys_vec: [in] array of physical vectors + * @nr_ranges: [in] number of entries in phys_vec array + * @size: [in] total size of phys_vec + * @dir: [in] direction of DMA transfer + * + * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR + * on error. May return -EINTR if it is interrupted by a signal. + * + * On success, the DMA addresses and lengths in the returned scatterlist are + * PAGE_SIZE aligned. + * + * A mapping must be unmapped by using dma_buf_free_sgt(). + * + * NOTE: This function is intended for exporters. If direct traffic routing is + * mandatory exporter should call routing pci_p2pdma_map_type() before calling + * this function. + */ +struct sg_table *dma_buf_phys_vec_to_sgt(struct dma_buf_attachment *attach, + struct p2pdma_provider *provider, + struct dma_buf_phys_vec *phys_vec, + size_t nr_ranges, size_t size, + enum dma_data_direction dir) +{ + unsigned int nents, mapped_len = 0; + struct dma_buf_dma *dma; + struct scatterlist *sgl; + dma_addr_t addr; + size_t i; + int ret; + + dma_resv_assert_held(attach->dmabuf->resv); + + if (WARN_ON(!attach || !attach->dmabuf || !provider)) + /* This function is supposed to work on MMIO memory only */ + return ERR_PTR(-EINVAL); + + dma = kzalloc(sizeof(*dma), GFP_KERNEL); + if (!dma) + return ERR_PTR(-ENOMEM); + + switch (pci_p2pdma_map_type(provider, attach->dev)) { + case PCI_P2PDMA_MAP_BUS_ADDR: + /* + * There is no need in IOVA at all for this flow. + */ + break; + case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: + dma->state = kzalloc(sizeof(*dma->state), GFP_KERNEL); + if (!dma->state) { + ret = -ENOMEM; + goto err_free_dma; + } + + dma_iova_try_alloc(attach->dev, dma->state, 0, size); + break; + default: + ret = -EINVAL; + goto err_free_dma; + } + + nents = calc_sg_nents(dma->state, phys_vec, nr_ranges, size); + ret = sg_alloc_table(&dma->sgt, nents, GFP_KERNEL | __GFP_ZERO); + if (ret) + goto err_free_state; + + sgl = dma->sgt.sgl; + + for (i = 0; i < nr_ranges; i++) { + if (!dma->state) { + addr = pci_p2pdma_bus_addr_map(provider, + phys_vec[i].paddr); + } else if (dma_use_iova(dma->state)) { + ret = dma_iova_link(attach->dev, dma->state, + phys_vec[i].paddr, 0, + phys_vec[i].len, dir, + DMA_ATTR_MMIO); + if (ret) + goto err_unmap_dma; + + mapped_len += phys_vec[i].len; + } else { + addr = dma_map_phys(attach->dev, phys_vec[i].paddr, + phys_vec[i].len, dir, + DMA_ATTR_MMIO); + ret = dma_mapping_error(attach->dev, addr); + if (ret) + goto err_unmap_dma; + } + + if (!dma->state || !dma_use_iova(dma->state)) + sgl = fill_sg_entry(sgl, phys_vec[i].len, addr); + } + + if (dma->state && dma_use_iova(dma->state)) { + WARN_ON_ONCE(mapped_len != size); + ret = dma_iova_sync(attach->dev, dma->state, 0, mapped_len); + if (ret) + goto err_unmap_dma; + + sgl = fill_sg_entry(sgl, mapped_len, dma->state->addr); + } + + dma->size = size; + + /* + * No CPU list included — set orig_nents = 0 so others can detect + * this via SG table (use nents only). + */ + dma->sgt.orig_nents = 0; + + + /* + * SGL must be NULL to indicate that SGL is the last one + * and we allocated correct number of entries in sg_alloc_table() + */ + WARN_ON_ONCE(sgl); + return &dma->sgt; + +err_unmap_dma: + if (!i || !dma->state) { + ; /* Do nothing */ + } else if (dma_use_iova(dma->state)) { + dma_iova_destroy(attach->dev, dma->state, mapped_len, dir, + DMA_ATTR_MMIO); + } else { + for_each_sgtable_dma_sg(&dma->sgt, sgl, i) + dma_unmap_phys(attach->dev, sg_dma_address(sgl), + sg_dma_len(sgl), dir, DMA_ATTR_MMIO); + } + sg_free_table(&dma->sgt); +err_free_state: + kfree(dma->state); +err_free_dma: + kfree(dma); + return ERR_PTR(ret); +} +EXPORT_SYMBOL_NS_GPL(dma_buf_phys_vec_to_sgt, "DMA_BUF"); + +/** + * dma_buf_free_sgt- unmaps the buffer + * @attach: [in] attachment to unmap buffer from + * @sgt: [in] scatterlist info of the buffer to unmap + * @dir: [in] direction of DMA transfer + * + * This unmaps a DMA mapping for @attached obtained + * by dma_buf_phys_vec_to_sgt(). + */ +void dma_buf_free_sgt(struct dma_buf_attachment *attach, struct sg_table *sgt, + enum dma_data_direction dir) +{ + struct dma_buf_dma *dma = container_of(sgt, struct dma_buf_dma, sgt); + int i; + + dma_resv_assert_held(attach->dmabuf->resv); + + if (!dma->state) { + ; /* Do nothing */ + } else if (dma_use_iova(dma->state)) { + dma_iova_destroy(attach->dev, dma->state, dma->size, dir, + DMA_ATTR_MMIO); + } else { + struct scatterlist *sgl; + + for_each_sgtable_dma_sg(sgt, sgl, i) + dma_unmap_phys(attach->dev, sg_dma_address(sgl), + sg_dma_len(sgl), dir, DMA_ATTR_MMIO); + } + + sg_free_table(sgt); + kfree(dma->state); + kfree(dma); + +} +EXPORT_SYMBOL_NS_GPL(dma_buf_free_sgt, "DMA_BUF"); diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 7944a3af4545..e52d19d2e833 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -1439,8 +1439,8 @@ int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents, * as a bus address, __finalise_sg() will copy the dma * address into the output segment. */ - s->dma_address = pci_p2pdma_bus_addr_map(&p2pdma_state, - sg_phys(s)); + s->dma_address = pci_p2pdma_bus_addr_map( + p2pdma_state.mem, sg_phys(s)); sg_dma_len(s) = sg->length; sg_dma_mark_bus_address(s); continue; diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 78e108e47254..981a76b6b7c0 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -25,12 +25,12 @@ struct pci_p2pdma { struct gen_pool *pool; bool p2pmem_published; struct xarray map_types; + struct p2pdma_provider mem[PCI_STD_NUM_BARS]; }; struct pci_p2pdma_pagemap { - struct pci_dev *provider; - u64 bus_offset; struct dev_pagemap pgmap; + struct p2pdma_provider *mem; }; static struct pci_p2pdma_pagemap *to_p2p_pgmap(struct dev_pagemap *pgmap) @@ -204,8 +204,8 @@ static void p2pdma_page_free(struct page *page) { struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(page_pgmap(page)); /* safe to dereference while a reference is held to the percpu ref */ - struct pci_p2pdma *p2pdma = - rcu_dereference_protected(pgmap->provider->p2pdma, 1); + struct pci_p2pdma *p2pdma = rcu_dereference_protected( + to_pci_dev(pgmap->mem->owner)->p2pdma, 1); struct percpu_ref *ref; gen_pool_free_owner(p2pdma->pool, (uintptr_t)page_to_virt(page), @@ -228,56 +228,136 @@ static void pci_p2pdma_release(void *data) /* Flush and disable pci_alloc_p2p_mem() */ pdev->p2pdma = NULL; - synchronize_rcu(); + if (p2pdma->pool) + synchronize_rcu(); + xa_destroy(&p2pdma->map_types); + + if (!p2pdma->pool) + return; gen_pool_destroy(p2pdma->pool); sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group); - xa_destroy(&p2pdma->map_types); } -static int pci_p2pdma_setup(struct pci_dev *pdev) +/** + * pcim_p2pdma_init - Initialise peer-to-peer DMA providers + * @pdev: The PCI device to enable P2PDMA for + * + * This function initializes the peer-to-peer DMA infrastructure + * for a PCI device. It allocates and sets up the necessary data + * structures to support P2PDMA operations, including mapping type + * tracking. + */ +int pcim_p2pdma_init(struct pci_dev *pdev) { - int error = -ENOMEM; struct pci_p2pdma *p2p; + int i, ret; + + p2p = rcu_dereference_protected(pdev->p2pdma, 1); + if (p2p) + return 0; p2p = devm_kzalloc(&pdev->dev, sizeof(*p2p), GFP_KERNEL); if (!p2p) return -ENOMEM; xa_init(&p2p->map_types); + /* + * Iterate over all standard PCI BARs and record only those that + * correspond to MMIO regions. Skip non-memory resources (e.g. I/O + * port BARs) since they cannot be used for peer-to-peer (P2P) + * transactions. + */ + for (i = 0; i < PCI_STD_NUM_BARS; i++) { + if (!(pci_resource_flags(pdev, i) & IORESOURCE_MEM)) + continue; - p2p->pool = gen_pool_create(PAGE_SHIFT, dev_to_node(&pdev->dev)); - if (!p2p->pool) - goto out; + p2p->mem[i].owner = &pdev->dev; + p2p->mem[i].bus_offset = + pci_bus_address(pdev, i) - pci_resource_start(pdev, i); + } - error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_release, pdev); - if (error) - goto out_pool_destroy; - - error = sysfs_create_group(&pdev->dev.kobj, &p2pmem_group); - if (error) - goto out_pool_destroy; + ret = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_release, pdev); + if (ret) + goto out_p2p; rcu_assign_pointer(pdev->p2pdma, p2p); return 0; -out_pool_destroy: - gen_pool_destroy(p2p->pool); -out: +out_p2p: devm_kfree(&pdev->dev, p2p); - return error; + return ret; +} +EXPORT_SYMBOL_GPL(pcim_p2pdma_init); + +/** + * pcim_p2pdma_provider - Get peer-to-peer DMA provider + * @pdev: The PCI device to enable P2PDMA for + * @bar: BAR index to get provider + * + * This function gets peer-to-peer DMA provider for a PCI device. The lifetime + * of the provider (and of course the MMIO) is bound to the lifetime of the + * driver. A driver calling this function must ensure that all references to the + * provider, and any DMA mappings created for any MMIO, are all cleaned up + * before the driver remove() completes. + * + * Since P2P is almost always shared with a second driver this means some system + * to notify, invalidate and revoke the MMIO's DMA must be in place to use this + * function. For example a revoke can be built using DMABUF. + */ +struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev, int bar) +{ + struct pci_p2pdma *p2p; + + if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM)) + return NULL; + + p2p = rcu_dereference_protected(pdev->p2pdma, 1); + if (WARN_ON(!p2p)) + /* Someone forgot to call to pcim_p2pdma_init() before */ + return NULL; + + return &p2p->mem[bar]; +} +EXPORT_SYMBOL_GPL(pcim_p2pdma_provider); + +static int pci_p2pdma_setup_pool(struct pci_dev *pdev) +{ + struct pci_p2pdma *p2pdma; + int ret; + + p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); + if (p2pdma->pool) + /* We already setup pools, do nothing, */ + return 0; + + p2pdma->pool = gen_pool_create(PAGE_SHIFT, dev_to_node(&pdev->dev)); + if (!p2pdma->pool) + return -ENOMEM; + + ret = sysfs_create_group(&pdev->dev.kobj, &p2pmem_group); + if (ret) + goto out_pool_destroy; + + return 0; + +out_pool_destroy: + gen_pool_destroy(p2pdma->pool); + p2pdma->pool = NULL; + return ret; } static void pci_p2pdma_unmap_mappings(void *data) { - struct pci_dev *pdev = data; + struct pci_p2pdma_pagemap *p2p_pgmap = data; /* * Removing the alloc attribute from sysfs will call * unmap_mapping_range() on the inode, teardown any existing userspace * mappings and prevent new ones from being created. */ - sysfs_remove_file_from_group(&pdev->dev.kobj, &p2pmem_alloc_attr.attr, + sysfs_remove_file_from_group(&p2p_pgmap->mem->owner->kobj, + &p2pmem_alloc_attr.attr, p2pmem_group.name); } @@ -295,6 +375,7 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, u64 offset) { struct pci_p2pdma_pagemap *p2p_pgmap; + struct p2pdma_provider *mem; struct dev_pagemap *pgmap; struct pci_p2pdma *p2pdma; void *addr; @@ -312,11 +393,21 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, if (size + offset > pci_resource_len(pdev, bar)) return -EINVAL; - if (!pdev->p2pdma) { - error = pci_p2pdma_setup(pdev); - if (error) - return error; - } + error = pcim_p2pdma_init(pdev); + if (error) + return error; + + error = pci_p2pdma_setup_pool(pdev); + if (error) + return error; + + mem = pcim_p2pdma_provider(pdev, bar); + /* + * We checked validity of BAR prior to call + * to pcim_p2pdma_provider. It should never return NULL. + */ + if (WARN_ON(!mem)) + return -EINVAL; p2p_pgmap = devm_kzalloc(&pdev->dev, sizeof(*p2p_pgmap), GFP_KERNEL); if (!p2p_pgmap) @@ -328,10 +419,7 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, pgmap->nr_range = 1; pgmap->type = MEMORY_DEVICE_PCI_P2PDMA; pgmap->ops = &p2pdma_pgmap_ops; - - p2p_pgmap->provider = pdev; - p2p_pgmap->bus_offset = pci_bus_address(pdev, bar) - - pci_resource_start(pdev, bar); + p2p_pgmap->mem = mem; addr = devm_memremap_pages(&pdev->dev, pgmap); if (IS_ERR(addr)) { @@ -340,7 +428,7 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, } error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_unmap_mappings, - pdev); + p2p_pgmap); if (error) goto pages_free; @@ -972,16 +1060,26 @@ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish) } EXPORT_SYMBOL_GPL(pci_p2pmem_publish); -static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap, - struct device *dev) +/** + * pci_p2pdma_map_type - Determine the mapping type for P2PDMA transfers + * @provider: P2PDMA provider structure + * @dev: Target device for the transfer + * + * Determines how peer-to-peer DMA transfers should be mapped between + * the provider and the target device. The mapping type indicates whether + * the transfer can be done directly through PCI switches or must go + * through the host bridge. + */ +enum pci_p2pdma_map_type pci_p2pdma_map_type(struct p2pdma_provider *provider, + struct device *dev) { enum pci_p2pdma_map_type type = PCI_P2PDMA_MAP_NOT_SUPPORTED; - struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider; + struct pci_dev *pdev = to_pci_dev(provider->owner); struct pci_dev *client; struct pci_p2pdma *p2pdma; int dist; - if (!provider->p2pdma) + if (!pdev->p2pdma) return PCI_P2PDMA_MAP_NOT_SUPPORTED; if (!dev_is_pci(dev)) @@ -990,7 +1088,7 @@ static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap, client = to_pci_dev(dev); rcu_read_lock(); - p2pdma = rcu_dereference(provider->p2pdma); + p2pdma = rcu_dereference(pdev->p2pdma); if (p2pdma) type = xa_to_value(xa_load(&p2pdma->map_types, @@ -998,7 +1096,7 @@ static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap, rcu_read_unlock(); if (type == PCI_P2PDMA_MAP_UNKNOWN) - return calc_map_type_and_dist(provider, client, &dist, true); + return calc_map_type_and_dist(pdev, client, &dist, true); return type; } @@ -1006,9 +1104,13 @@ static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap, void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state, struct device *dev, struct page *page) { - state->pgmap = page_pgmap(page); - state->map = pci_p2pdma_map_type(state->pgmap, dev); - state->bus_off = to_p2p_pgmap(state->pgmap)->bus_offset; + struct pci_p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(page_pgmap(page)); + + if (state->mem == p2p_pgmap->mem) + return; + + state->mem = p2p_pgmap->mem; + state->map = pci_p2pdma_map_type(p2p_pgmap->mem, dev); } /** diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig index 2b0172f54665..2b9fca00e9e8 100644 --- a/drivers/vfio/pci/Kconfig +++ b/drivers/vfio/pci/Kconfig @@ -55,6 +55,9 @@ config VFIO_PCI_ZDEV_KVM To enable s390x KVM vfio-pci extensions, say Y. +config VFIO_PCI_DMABUF + def_bool y if VFIO_PCI_CORE && PCI_P2PDMA && DMA_SHARED_BUFFER + source "drivers/vfio/pci/mlx5/Kconfig" source "drivers/vfio/pci/hisilicon/Kconfig" diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile index cf00c0a7e55c..53f59226ae01 100644 --- a/drivers/vfio/pci/Makefile +++ b/drivers/vfio/pci/Makefile @@ -2,6 +2,7 @@ vfio-pci-core-y := vfio_pci_core.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o vfio-pci-core-$(CONFIG_VFIO_PCI_ZDEV_KVM) += vfio_pci_zdev.o +vfio-pci-core-$(CONFIG_VFIO_PCI_DMABUF) += vfio_pci_dmabuf.o obj-$(CONFIG_VFIO_PCI_CORE) += vfio-pci-core.o vfio-pci-y := vfio_pci.o diff --git a/drivers/vfio/pci/nvgrace-gpu/main.c b/drivers/vfio/pci/nvgrace-gpu/main.c index 5a6f77d5c81e..e33f24fbb0a4 100644 --- a/drivers/vfio/pci/nvgrace-gpu/main.c +++ b/drivers/vfio/pci/nvgrace-gpu/main.c @@ -7,6 +7,7 @@ #include #include #include +#include /* * The device memory usable to the workloads running in the VM is cached @@ -652,6 +653,50 @@ nvgrace_gpu_write(struct vfio_device *core_vdev, return vfio_pci_core_write(core_vdev, buf, count, ppos); } +static int nvgrace_get_dmabuf_phys(struct vfio_pci_core_device *core_vdev, + struct p2pdma_provider **provider, + unsigned int region_index, + struct dma_buf_phys_vec *phys_vec, + struct vfio_region_dma_range *dma_ranges, + size_t nr_ranges) +{ + struct nvgrace_gpu_pci_core_device *nvdev = container_of( + core_vdev, struct nvgrace_gpu_pci_core_device, core_device); + struct pci_dev *pdev = core_vdev->pdev; + struct mem_region *mem_region; + + /* + * if (nvdev->resmem.memlength && region_index == RESMEM_REGION_INDEX) { + * The P2P properties of the non-BAR memory is the same as the + * BAR memory, so just use the provider for index 0. Someday + * when CXL gets P2P support we could create CXLish providers + * for the non-BAR memory. + * } else if (region_index == USEMEM_REGION_INDEX) { + * This is actually cachable memory and isn't treated as P2P in + * the chip. For now we have no way to push cachable memory + * through everything and the Grace HW doesn't care what caching + * attribute is programmed into the SMMU. So use BAR 0. + * } + */ + mem_region = nvgrace_gpu_memregion(region_index, nvdev); + if (mem_region) { + *provider = pcim_p2pdma_provider(pdev, 0); + if (!*provider) + return -EINVAL; + return vfio_pci_core_fill_phys_vec(phys_vec, dma_ranges, + nr_ranges, + mem_region->memphys, + mem_region->memlength); + } + + return vfio_pci_core_get_dmabuf_phys(core_vdev, provider, region_index, + phys_vec, dma_ranges, nr_ranges); +} + +static const struct vfio_pci_device_ops nvgrace_gpu_pci_dev_ops = { + .get_dmabuf_phys = nvgrace_get_dmabuf_phys, +}; + static const struct vfio_device_ops nvgrace_gpu_pci_ops = { .name = "nvgrace-gpu-vfio-pci", .init = vfio_pci_core_init_dev, @@ -673,6 +718,10 @@ static const struct vfio_device_ops nvgrace_gpu_pci_ops = { .detach_ioas = vfio_iommufd_physical_detach_ioas, }; +static const struct vfio_pci_device_ops nvgrace_gpu_pci_dev_core_ops = { + .get_dmabuf_phys = vfio_pci_core_get_dmabuf_phys, +}; + static const struct vfio_device_ops nvgrace_gpu_pci_core_ops = { .name = "nvgrace-gpu-vfio-pci-core", .init = vfio_pci_core_init_dev, @@ -936,6 +985,9 @@ static int nvgrace_gpu_probe(struct pci_dev *pdev, memphys, memlength); if (ret) goto out_put_vdev; + nvdev->core_device.pci_ops = &nvgrace_gpu_pci_dev_ops; + } else { + nvdev->core_device.pci_ops = &nvgrace_gpu_pci_dev_core_ops; } ret = vfio_pci_core_register_device(&nvdev->core_device); diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index a3e49d42c771..0c771064c0b8 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -148,6 +148,10 @@ static const struct vfio_device_ops vfio_pci_ops = { .pasid_detach_ioas = vfio_iommufd_physical_pasid_detach_ioas, }; +static const struct vfio_pci_device_ops vfio_pci_dev_ops = { + .get_dmabuf_phys = vfio_pci_core_get_dmabuf_phys, +}; + static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) { struct vfio_pci_core_device *vdev; @@ -162,6 +166,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) return PTR_ERR(vdev); dev_set_drvdata(&pdev->dev, vdev); + vdev->pci_ops = &vfio_pci_dev_ops; ret = vfio_pci_core_register_device(vdev); if (ret) goto out_put_vdev; diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c index 8f02f236b5b4..1f6008eabf23 100644 --- a/drivers/vfio/pci/vfio_pci_config.c +++ b/drivers/vfio/pci/vfio_pci_config.c @@ -589,10 +589,12 @@ static int vfio_basic_config_write(struct vfio_pci_core_device *vdev, int pos, virt_mem = !!(le16_to_cpu(*virt_cmd) & PCI_COMMAND_MEMORY); new_mem = !!(new_cmd & PCI_COMMAND_MEMORY); - if (!new_mem) + if (!new_mem) { vfio_pci_zap_and_down_write_memory_lock(vdev); - else + vfio_pci_dma_buf_move(vdev, true); + } else { down_write(&vdev->memory_lock); + } /* * If the user is writing mem/io enable (new_mem/io) and we @@ -627,6 +629,8 @@ static int vfio_basic_config_write(struct vfio_pci_core_device *vdev, int pos, *virt_cmd &= cpu_to_le16(~mask); *virt_cmd |= cpu_to_le16(new_cmd & mask); + if (__vfio_pci_memory_enabled(vdev)) + vfio_pci_dma_buf_move(vdev, false); up_write(&vdev->memory_lock); } @@ -707,12 +711,16 @@ static int __init init_pci_cap_basic_perm(struct perm_bits *perm) static void vfio_lock_and_set_power_state(struct vfio_pci_core_device *vdev, pci_power_t state) { - if (state >= PCI_D3hot) + if (state >= PCI_D3hot) { vfio_pci_zap_and_down_write_memory_lock(vdev); - else + vfio_pci_dma_buf_move(vdev, true); + } else { down_write(&vdev->memory_lock); + } vfio_pci_set_power_state(vdev, state); + if (__vfio_pci_memory_enabled(vdev)) + vfio_pci_dma_buf_move(vdev, false); up_write(&vdev->memory_lock); } @@ -900,7 +908,10 @@ static int vfio_exp_config_write(struct vfio_pci_core_device *vdev, int pos, if (!ret && (cap & PCI_EXP_DEVCAP_FLR)) { vfio_pci_zap_and_down_write_memory_lock(vdev); + vfio_pci_dma_buf_move(vdev, true); pci_try_reset_function(vdev->pdev); + if (__vfio_pci_memory_enabled(vdev)) + vfio_pci_dma_buf_move(vdev, false); up_write(&vdev->memory_lock); } } @@ -982,7 +993,10 @@ static int vfio_af_config_write(struct vfio_pci_core_device *vdev, int pos, if (!ret && (cap & PCI_AF_CAP_FLR) && (cap & PCI_AF_CAP_TP)) { vfio_pci_zap_and_down_write_memory_lock(vdev); + vfio_pci_dma_buf_move(vdev, true); pci_try_reset_function(vdev->pdev); + if (__vfio_pci_memory_enabled(vdev)) + vfio_pci_dma_buf_move(vdev, false); up_write(&vdev->memory_lock); } } diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index 57c0766fb9f8..79a1a50a4ef7 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -28,6 +28,7 @@ #include #include #include +#include #if IS_ENABLED(CONFIG_EEH) #include #endif @@ -286,6 +287,8 @@ static int vfio_pci_runtime_pm_entry(struct vfio_pci_core_device *vdev, * semaphore. */ vfio_pci_zap_and_down_write_memory_lock(vdev); + vfio_pci_dma_buf_move(vdev, true); + if (vdev->pm_runtime_engaged) { up_write(&vdev->memory_lock); return -EINVAL; @@ -299,11 +302,9 @@ static int vfio_pci_runtime_pm_entry(struct vfio_pci_core_device *vdev, return 0; } -static int vfio_pci_core_pm_entry(struct vfio_device *device, u32 flags, +static int vfio_pci_core_pm_entry(struct vfio_pci_core_device *vdev, u32 flags, void __user *arg, size_t argsz) { - struct vfio_pci_core_device *vdev = - container_of(device, struct vfio_pci_core_device, vdev); int ret; ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_SET, 0); @@ -320,12 +321,10 @@ static int vfio_pci_core_pm_entry(struct vfio_device *device, u32 flags, } static int vfio_pci_core_pm_entry_with_wakeup( - struct vfio_device *device, u32 flags, + struct vfio_pci_core_device *vdev, u32 flags, struct vfio_device_low_power_entry_with_wakeup __user *arg, size_t argsz) { - struct vfio_pci_core_device *vdev = - container_of(device, struct vfio_pci_core_device, vdev); struct vfio_device_low_power_entry_with_wakeup entry; struct eventfd_ctx *efdctx; int ret; @@ -373,14 +372,14 @@ static void vfio_pci_runtime_pm_exit(struct vfio_pci_core_device *vdev) */ down_write(&vdev->memory_lock); __vfio_pci_runtime_pm_exit(vdev); + if (__vfio_pci_memory_enabled(vdev)) + vfio_pci_dma_buf_move(vdev, false); up_write(&vdev->memory_lock); } -static int vfio_pci_core_pm_exit(struct vfio_device *device, u32 flags, +static int vfio_pci_core_pm_exit(struct vfio_pci_core_device *vdev, u32 flags, void __user *arg, size_t argsz) { - struct vfio_pci_core_device *vdev = - container_of(device, struct vfio_pci_core_device, vdev); int ret; ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_SET, 0); @@ -695,6 +694,8 @@ void vfio_pci_core_close_device(struct vfio_device *core_vdev) #endif vfio_pci_core_disable(vdev); + vfio_pci_dma_buf_cleanup(vdev); + mutex_lock(&vdev->igate); if (vdev->err_trigger) { eventfd_ctx_put(vdev->err_trigger); @@ -1205,7 +1206,10 @@ static int vfio_pci_ioctl_reset(struct vfio_pci_core_device *vdev, */ vfio_pci_set_power_state(vdev, PCI_D0); + vfio_pci_dma_buf_move(vdev, true); ret = pci_try_reset_function(vdev->pdev); + if (__vfio_pci_memory_enabled(vdev)) + vfio_pci_dma_buf_move(vdev, false); up_write(&vdev->memory_lock); return ret; @@ -1449,11 +1453,10 @@ long vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd, } EXPORT_SYMBOL_GPL(vfio_pci_core_ioctl); -static int vfio_pci_core_feature_token(struct vfio_device *device, u32 flags, - uuid_t __user *arg, size_t argsz) +static int vfio_pci_core_feature_token(struct vfio_pci_core_device *vdev, + u32 flags, uuid_t __user *arg, + size_t argsz) { - struct vfio_pci_core_device *vdev = - container_of(device, struct vfio_pci_core_device, vdev); uuid_t uuid; int ret; @@ -1480,16 +1483,21 @@ static int vfio_pci_core_feature_token(struct vfio_device *device, u32 flags, int vfio_pci_core_ioctl_feature(struct vfio_device *device, u32 flags, void __user *arg, size_t argsz) { + struct vfio_pci_core_device *vdev = + container_of(device, struct vfio_pci_core_device, vdev); + switch (flags & VFIO_DEVICE_FEATURE_MASK) { case VFIO_DEVICE_FEATURE_LOW_POWER_ENTRY: - return vfio_pci_core_pm_entry(device, flags, arg, argsz); + return vfio_pci_core_pm_entry(vdev, flags, arg, argsz); case VFIO_DEVICE_FEATURE_LOW_POWER_ENTRY_WITH_WAKEUP: - return vfio_pci_core_pm_entry_with_wakeup(device, flags, + return vfio_pci_core_pm_entry_with_wakeup(vdev, flags, arg, argsz); case VFIO_DEVICE_FEATURE_LOW_POWER_EXIT: - return vfio_pci_core_pm_exit(device, flags, arg, argsz); + return vfio_pci_core_pm_exit(vdev, flags, arg, argsz); case VFIO_DEVICE_FEATURE_PCI_VF_TOKEN: - return vfio_pci_core_feature_token(device, flags, arg, argsz); + return vfio_pci_core_feature_token(vdev, flags, arg, argsz); + case VFIO_DEVICE_FEATURE_DMA_BUF: + return vfio_pci_core_feature_dma_buf(vdev, flags, arg, argsz); default: return -ENOTTY; } @@ -2061,6 +2069,7 @@ int vfio_pci_core_init_dev(struct vfio_device *core_vdev) { struct vfio_pci_core_device *vdev = container_of(core_vdev, struct vfio_pci_core_device, vdev); + int ret; vdev->pdev = to_pci_dev(core_vdev->dev); vdev->irq_type = VFIO_PCI_NUM_IRQS; @@ -2070,6 +2079,10 @@ int vfio_pci_core_init_dev(struct vfio_device *core_vdev) INIT_LIST_HEAD(&vdev->dummy_resources_list); INIT_LIST_HEAD(&vdev->ioeventfds_list); INIT_LIST_HEAD(&vdev->sriov_pfs_item); + ret = pcim_p2pdma_init(vdev->pdev); + if (ret && ret != -EOPNOTSUPP) + return ret; + INIT_LIST_HEAD(&vdev->dmabufs); init_rwsem(&vdev->memory_lock); xa_init(&vdev->ctx); @@ -2434,6 +2447,7 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set, break; } + vfio_pci_dma_buf_move(vdev, true); vfio_pci_zap_bars(vdev); } @@ -2462,8 +2476,11 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set, err_undo: list_for_each_entry_from_reverse(vdev, &dev_set->device_list, - vdev.dev_set_list) + vdev.dev_set_list) { + if (vdev->vdev.open_count && __vfio_pci_memory_enabled(vdev)) + vfio_pci_dma_buf_move(vdev, false); up_write(&vdev->memory_lock); + } list_for_each_entry(vdev, &dev_set->device_list, vdev.dev_set_list) pm_runtime_put(&vdev->pdev->dev); diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c new file mode 100644 index 000000000000..6698f540bdac --- /dev/null +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c @@ -0,0 +1,316 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2025, NVIDIA CORPORATION & AFFILIATES. + */ +#include +#include +#include + +#include "vfio_pci_priv.h" + +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 dma_buf_phys_vec *phys_vec; + struct p2pdma_provider *provider; + u32 nr_ranges; + u8 revoked : 1; +}; + +static int vfio_pci_dma_buf_attach(struct dma_buf *dmabuf, + struct dma_buf_attachment *attachment) +{ + struct vfio_pci_dma_buf *priv = dmabuf->priv; + + if (!attachment->peer2peer) + return -EOPNOTSUPP; + + if (priv->revoked) + return -ENODEV; + + return 0; +} + +static struct sg_table * +vfio_pci_dma_buf_map(struct dma_buf_attachment *attachment, + enum dma_data_direction dir) +{ + struct vfio_pci_dma_buf *priv = attachment->dmabuf->priv; + + dma_resv_assert_held(priv->dmabuf->resv); + + if (priv->revoked) + return ERR_PTR(-ENODEV); + + return dma_buf_phys_vec_to_sgt(attachment, priv->provider, + priv->phys_vec, priv->nr_ranges, + priv->size, dir); +} + +static void vfio_pci_dma_buf_unmap(struct dma_buf_attachment *attachment, + struct sg_table *sgt, + enum dma_data_direction dir) +{ + dma_buf_free_sgt(attachment, sgt, dir); +} + +static void vfio_pci_dma_buf_release(struct dma_buf *dmabuf) +{ + struct vfio_pci_dma_buf *priv = dmabuf->priv; + + /* + * Either this or vfio_pci_dma_buf_cleanup() will remove from the list. + * The refcount prevents both. + */ + if (priv->vdev) { + down_write(&priv->vdev->memory_lock); + list_del_init(&priv->dmabufs_elm); + up_write(&priv->vdev->memory_lock); + vfio_device_put_registration(&priv->vdev->vdev); + } + kfree(priv->phys_vec); + kfree(priv); +} + +static const struct dma_buf_ops vfio_pci_dmabuf_ops = { + .attach = vfio_pci_dma_buf_attach, + .map_dma_buf = vfio_pci_dma_buf_map, + .unmap_dma_buf = vfio_pci_dma_buf_unmap, + .release = vfio_pci_dma_buf_release, +}; + +int vfio_pci_core_fill_phys_vec(struct dma_buf_phys_vec *phys_vec, + struct vfio_region_dma_range *dma_ranges, + size_t nr_ranges, phys_addr_t start, + phys_addr_t len) +{ + phys_addr_t max_addr; + unsigned int i; + + max_addr = start + len; + for (i = 0; i < nr_ranges; i++) { + phys_addr_t end; + + if (!dma_ranges[i].length) + return -EINVAL; + + if (check_add_overflow(start, dma_ranges[i].offset, + &phys_vec[i].paddr) || + check_add_overflow(phys_vec[i].paddr, + dma_ranges[i].length, &end)) + return -EOVERFLOW; + if (end > max_addr) + return -EINVAL; + + phys_vec[i].len = dma_ranges[i].length; + } + return 0; +} +EXPORT_SYMBOL_GPL(vfio_pci_core_fill_phys_vec); + +int vfio_pci_core_get_dmabuf_phys(struct vfio_pci_core_device *vdev, + struct p2pdma_provider **provider, + unsigned int region_index, + struct dma_buf_phys_vec *phys_vec, + struct vfio_region_dma_range *dma_ranges, + size_t nr_ranges) +{ + struct pci_dev *pdev = vdev->pdev; + + *provider = pcim_p2pdma_provider(pdev, region_index); + if (!*provider) + return -EINVAL; + + return vfio_pci_core_fill_phys_vec( + phys_vec, dma_ranges, nr_ranges, + pci_resource_start(pdev, region_index), + pci_resource_len(pdev, region_index)); +} +EXPORT_SYMBOL_GPL(vfio_pci_core_get_dmabuf_phys); + +static int validate_dmabuf_input(struct vfio_device_feature_dma_buf *dma_buf, + struct vfio_region_dma_range *dma_ranges, + size_t *lengthp) +{ + size_t length = 0; + u32 i; + + for (i = 0; i < dma_buf->nr_ranges; i++) { + u64 offset = dma_ranges[i].offset; + u64 len = dma_ranges[i].length; + + if (!len || !PAGE_ALIGNED(offset) || !PAGE_ALIGNED(len)) + return -EINVAL; + + if (check_add_overflow(length, len, &length)) + return -EINVAL; + } + + /* + * dma_iova_try_alloc() will WARN on if userspace proposes a size that + * is too big, eg with lots of ranges. + */ + if ((u64)(length) & DMA_IOVA_USE_SWIOTLB) + return -EINVAL; + + *lengthp = length; + return 0; +} + +int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, + struct vfio_device_feature_dma_buf __user *arg, + size_t argsz) +{ + struct vfio_device_feature_dma_buf get_dma_buf = {}; + struct vfio_region_dma_range *dma_ranges; + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); + struct vfio_pci_dma_buf *priv; + size_t length; + int ret; + + if (!vdev->pci_ops || !vdev->pci_ops->get_dmabuf_phys) + return -EOPNOTSUPP; + + ret = vfio_check_feature(flags, argsz, VFIO_DEVICE_FEATURE_GET, + sizeof(get_dma_buf)); + if (ret != 1) + return ret; + + if (copy_from_user(&get_dma_buf, arg, sizeof(get_dma_buf))) + return -EFAULT; + + if (!get_dma_buf.nr_ranges || get_dma_buf.flags) + return -EINVAL; + + /* + * For PCI the region_index is the BAR number like everything else. + */ + if (get_dma_buf.region_index >= VFIO_PCI_ROM_REGION_INDEX) + return -ENODEV; + + dma_ranges = memdup_array_user(&arg->dma_ranges, get_dma_buf.nr_ranges, + sizeof(*dma_ranges)); + if (IS_ERR(dma_ranges)) + return PTR_ERR(dma_ranges); + + ret = validate_dmabuf_input(&get_dma_buf, dma_ranges, &length); + if (ret) + goto err_free_ranges; + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) { + ret = -ENOMEM; + goto err_free_ranges; + } + priv->phys_vec = kcalloc(get_dma_buf.nr_ranges, sizeof(*priv->phys_vec), + GFP_KERNEL); + if (!priv->phys_vec) { + ret = -ENOMEM; + goto err_free_priv; + } + + priv->vdev = vdev; + priv->nr_ranges = get_dma_buf.nr_ranges; + priv->size = length; + ret = vdev->pci_ops->get_dmabuf_phys(vdev, &priv->provider, + get_dma_buf.region_index, + priv->phys_vec, dma_ranges, + priv->nr_ranges); + if (ret) + goto err_free_phys; + + kfree(dma_ranges); + dma_ranges = NULL; + + if (!vfio_device_try_get_registration(&vdev->vdev)) { + ret = -ENODEV; + goto err_free_phys; + } + + exp_info.ops = &vfio_pci_dmabuf_ops; + exp_info.size = priv->size; + exp_info.flags = get_dma_buf.open_flags; + exp_info.priv = priv; + + priv->dmabuf = dma_buf_export(&exp_info); + if (IS_ERR(priv->dmabuf)) { + ret = PTR_ERR(priv->dmabuf); + goto err_dev_put; + } + + /* dma_buf_put() now frees priv */ + INIT_LIST_HEAD(&priv->dmabufs_elm); + down_write(&vdev->memory_lock); + dma_resv_lock(priv->dmabuf->resv, NULL); + priv->revoked = !__vfio_pci_memory_enabled(vdev); + list_add_tail(&priv->dmabufs_elm, &vdev->dmabufs); + dma_resv_unlock(priv->dmabuf->resv); + up_write(&vdev->memory_lock); + + /* + * dma_buf_fd() consumes the reference, when the file closes the dmabuf + * will be released. + */ + ret = dma_buf_fd(priv->dmabuf, get_dma_buf.open_flags); + if (ret < 0) + goto err_dma_buf; + return ret; + +err_dma_buf: + dma_buf_put(priv->dmabuf); +err_dev_put: + vfio_device_put_registration(&vdev->vdev); +err_free_phys: + kfree(priv->phys_vec); +err_free_priv: + kfree(priv); +err_free_ranges: + kfree(dma_ranges); + return ret; +} + +void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, bool revoked) +{ + struct vfio_pci_dma_buf *priv; + struct vfio_pci_dma_buf *tmp; + + lockdep_assert_held_write(&vdev->memory_lock); + + list_for_each_entry_safe(priv, tmp, &vdev->dmabufs, dmabufs_elm) { + if (!get_file_active(&priv->dmabuf->file)) + continue; + + if (priv->revoked != revoked) { + dma_resv_lock(priv->dmabuf->resv, NULL); + priv->revoked = revoked; + dma_buf_move_notify(priv->dmabuf); + dma_resv_unlock(priv->dmabuf->resv); + } + fput(priv->dmabuf->file); + } +} + +void vfio_pci_dma_buf_cleanup(struct vfio_pci_core_device *vdev) +{ + struct vfio_pci_dma_buf *priv; + struct vfio_pci_dma_buf *tmp; + + down_write(&vdev->memory_lock); + list_for_each_entry_safe(priv, tmp, &vdev->dmabufs, dmabufs_elm) { + if (!get_file_active(&priv->dmabuf->file)) + continue; + + dma_resv_lock(priv->dmabuf->resv, NULL); + list_del_init(&priv->dmabufs_elm); + priv->vdev = NULL; + priv->revoked = true; + dma_buf_move_notify(priv->dmabuf); + dma_resv_unlock(priv->dmabuf->resv); + vfio_device_put_registration(&vdev->vdev); + fput(priv->dmabuf->file); + } + up_write(&vdev->memory_lock); +} diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci_priv.h index a9972eacb293..28a405f8b97c 100644 --- a/drivers/vfio/pci/vfio_pci_priv.h +++ b/drivers/vfio/pci/vfio_pci_priv.h @@ -107,4 +107,27 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev) return (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA; } +#ifdef CONFIG_VFIO_PCI_DMABUF +int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, + struct vfio_device_feature_dma_buf __user *arg, + size_t argsz); +void vfio_pci_dma_buf_cleanup(struct vfio_pci_core_device *vdev); +void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, bool revoked); +#else +static inline int +vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, + struct vfio_device_feature_dma_buf __user *arg, + size_t argsz) +{ + return -ENOTTY; +} +static inline void vfio_pci_dma_buf_cleanup(struct vfio_pci_core_device *vdev) +{ +} +static inline void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev, + bool revoked) +{ +} +#endif + #endif diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index b8fe1a75e48a..f7df90c423b4 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -172,11 +172,13 @@ void vfio_device_put_registration(struct vfio_device *device) if (refcount_dec_and_test(&device->refcount)) complete(&device->comp); } +EXPORT_SYMBOL_GPL(vfio_device_put_registration); bool vfio_device_try_get_registration(struct vfio_device *device) { return refcount_inc_not_zero(&device->refcount); } +EXPORT_SYMBOL_GPL(vfio_device_try_get_registration); /* * VFIO driver API diff --git a/include/linux/dma-buf-mapping.h b/include/linux/dma-buf-mapping.h new file mode 100644 index 000000000000..a3c0ce2d3a42 --- /dev/null +++ b/include/linux/dma-buf-mapping.h @@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * DMA BUF Mapping Helpers + * + */ +#ifndef __DMA_BUF_MAPPING_H__ +#define __DMA_BUF_MAPPING_H__ +#include + +struct sg_table *dma_buf_phys_vec_to_sgt(struct dma_buf_attachment *attach, + struct p2pdma_provider *provider, + struct dma_buf_phys_vec *phys_vec, + size_t nr_ranges, size_t size, + enum dma_data_direction dir); +void dma_buf_free_sgt(struct dma_buf_attachment *attach, struct sg_table *sgt, + enum dma_data_direction dir); +#endif diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index d58e329ac0e7..0bc492090237 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -22,6 +22,7 @@ #include #include #include +#include struct device; struct dma_buf; @@ -530,6 +531,16 @@ struct dma_buf_export_info { void *priv; }; +/** + * struct dma_buf_phys_vec - describe continuous chunk of memory + * @paddr: physical address of that chunk + * @len: Length of this chunk + */ +struct dma_buf_phys_vec { + phys_addr_t paddr; + size_t len; +}; + /** * DEFINE_DMA_BUF_EXPORT_INFO - helper macro for exporters * @name: export-info name diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h index 951f81a38f3a..517e121d2598 100644 --- a/include/linux/pci-p2pdma.h +++ b/include/linux/pci-p2pdma.h @@ -16,7 +16,58 @@ struct block_device; struct scatterlist; +/** + * struct p2pdma_provider + * + * A p2pdma provider is a range of MMIO address space available to the CPU. + */ +struct p2pdma_provider { + struct device *owner; + u64 bus_offset; +}; + +enum pci_p2pdma_map_type { + /* + * PCI_P2PDMA_MAP_UNKNOWN: Used internally as an initial state before + * the mapping type has been calculated. Exported routines for the API + * will never return this value. + */ + PCI_P2PDMA_MAP_UNKNOWN = 0, + + /* + * Not a PCI P2PDMA transfer. + */ + PCI_P2PDMA_MAP_NONE, + + /* + * PCI_P2PDMA_MAP_NOT_SUPPORTED: Indicates the transaction will + * traverse the host bridge and the host bridge is not in the + * allowlist. DMA Mapping routines should return an error when + * this is returned. + */ + PCI_P2PDMA_MAP_NOT_SUPPORTED, + + /* + * PCI_P2PDMA_MAP_BUS_ADDR: Indicates that two devices can talk to + * each other directly through a PCI switch and the transaction will + * not traverse the host bridge. Such a mapping should program + * the DMA engine with PCI bus addresses. + */ + PCI_P2PDMA_MAP_BUS_ADDR, + + /* + * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: Indicates two devices can talk + * to each other, but the transaction traverses a host bridge on the + * allowlist. In this case, a normal mapping either with CPU physical + * addresses (in the case of dma-direct) or IOVA addresses (in the + * case of IOMMUs) should be used to program the DMA engine. + */ + PCI_P2PDMA_MAP_THRU_HOST_BRIDGE, +}; + #ifdef CONFIG_PCI_P2PDMA +int pcim_p2pdma_init(struct pci_dev *pdev); +struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev, int bar); int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, u64 offset); int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients, @@ -33,7 +84,18 @@ int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev, bool *use_p2pdma); ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev, bool use_p2pdma); +enum pci_p2pdma_map_type pci_p2pdma_map_type(struct p2pdma_provider *provider, + struct device *dev); #else /* CONFIG_PCI_P2PDMA */ +static inline int pcim_p2pdma_init(struct pci_dev *pdev) +{ + return -EOPNOTSUPP; +} +static inline struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev, + int bar) +{ + return NULL; +} static inline int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, u64 offset) { @@ -85,6 +147,11 @@ static inline ssize_t pci_p2pdma_enable_show(char *page, { return sprintf(page, "none\n"); } +static inline enum pci_p2pdma_map_type +pci_p2pdma_map_type(struct p2pdma_provider *provider, struct device *dev) +{ + return PCI_P2PDMA_MAP_NOT_SUPPORTED; +} #endif /* CONFIG_PCI_P2PDMA */ @@ -99,51 +166,12 @@ static inline struct pci_dev *pci_p2pmem_find(struct device *client) return pci_p2pmem_find_many(&client, 1); } -enum pci_p2pdma_map_type { - /* - * PCI_P2PDMA_MAP_UNKNOWN: Used internally as an initial state before - * the mapping type has been calculated. Exported routines for the API - * will never return this value. - */ - PCI_P2PDMA_MAP_UNKNOWN = 0, - - /* - * Not a PCI P2PDMA transfer. - */ - PCI_P2PDMA_MAP_NONE, - - /* - * PCI_P2PDMA_MAP_NOT_SUPPORTED: Indicates the transaction will - * traverse the host bridge and the host bridge is not in the - * allowlist. DMA Mapping routines should return an error when - * this is returned. - */ - PCI_P2PDMA_MAP_NOT_SUPPORTED, - - /* - * PCI_P2PDMA_MAP_BUS_ADDR: Indicates that two devices can talk to - * each other directly through a PCI switch and the transaction will - * not traverse the host bridge. Such a mapping should program - * the DMA engine with PCI bus addresses. - */ - PCI_P2PDMA_MAP_BUS_ADDR, - - /* - * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: Indicates two devices can talk - * to each other, but the transaction traverses a host bridge on the - * allowlist. In this case, a normal mapping either with CPU physical - * addresses (in the case of dma-direct) or IOVA addresses (in the - * case of IOMMUs) should be used to program the DMA engine. - */ - PCI_P2PDMA_MAP_THRU_HOST_BRIDGE, -}; - struct pci_p2pdma_map_state { - struct dev_pagemap *pgmap; + struct p2pdma_provider *mem; enum pci_p2pdma_map_type map; - u64 bus_off; }; + /* helper for pci_p2pdma_state(), do not use directly */ void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state, struct device *dev, struct page *page); @@ -162,8 +190,7 @@ pci_p2pdma_state(struct pci_p2pdma_map_state *state, struct device *dev, struct page *page) { if (IS_ENABLED(CONFIG_PCI_P2PDMA) && is_pci_p2pdma_page(page)) { - if (state->pgmap != page_pgmap(page)) - __pci_p2pdma_update_state(state, dev, page); + __pci_p2pdma_update_state(state, dev, page); return state->map; } return PCI_P2PDMA_MAP_NONE; @@ -172,16 +199,15 @@ pci_p2pdma_state(struct pci_p2pdma_map_state *state, struct device *dev, /** * pci_p2pdma_bus_addr_map - Translate a physical address to a bus address * for a PCI_P2PDMA_MAP_BUS_ADDR transfer. - * @state: P2P state structure + * @provider: P2P provider structure * @paddr: physical address to map * * Map a physically contiguous PCI_P2PDMA_MAP_BUS_ADDR transfer. */ static inline dma_addr_t -pci_p2pdma_bus_addr_map(struct pci_p2pdma_map_state *state, phys_addr_t paddr) +pci_p2pdma_bus_addr_map(struct p2pdma_provider *provider, phys_addr_t paddr) { - WARN_ON_ONCE(state->map != PCI_P2PDMA_MAP_BUS_ADDR); - return paddr + state->bus_off; + return paddr + provider->bus_offset; } #endif /* _LINUX_PCI_P2P_H */ diff --git a/include/linux/vfio.h b/include/linux/vfio.h index 8e1ddb48b9b5..e90859956514 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -301,6 +301,8 @@ static inline void vfio_put_device(struct vfio_device *device) int vfio_register_group_dev(struct vfio_device *device); int vfio_register_emulated_iommu_dev(struct vfio_device *device); void vfio_unregister_group_dev(struct vfio_device *device); +bool vfio_device_try_get_registration(struct vfio_device *device); +void vfio_device_put_registration(struct vfio_device *device); int vfio_assign_device_set(struct vfio_device *device, void *set_id); unsigned int vfio_device_set_open_count(struct vfio_device_set *dev_set); diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h index e74f94c17fbe..88fd2fd895d0 100644 --- a/include/linux/vfio_pci_core.h +++ b/include/linux/vfio_pci_core.h @@ -26,6 +26,8 @@ struct vfio_pci_core_device; struct vfio_pci_region; +struct p2pdma_provider; +struct dma_buf_phys_vec; struct vfio_pci_regops { ssize_t (*rw)(struct vfio_pci_core_device *vdev, char __user *buf, @@ -49,9 +51,48 @@ struct vfio_pci_region { u32 flags; }; +struct vfio_pci_device_ops { + int (*get_dmabuf_phys)(struct vfio_pci_core_device *vdev, + struct p2pdma_provider **provider, + unsigned int region_index, + struct dma_buf_phys_vec *phys_vec, + struct vfio_region_dma_range *dma_ranges, + size_t nr_ranges); +}; + +#if IS_ENABLED(CONFIG_VFIO_PCI_DMABUF) +int vfio_pci_core_fill_phys_vec(struct dma_buf_phys_vec *phys_vec, + struct vfio_region_dma_range *dma_ranges, + size_t nr_ranges, phys_addr_t start, + phys_addr_t len); +int vfio_pci_core_get_dmabuf_phys(struct vfio_pci_core_device *vdev, + struct p2pdma_provider **provider, + unsigned int region_index, + struct dma_buf_phys_vec *phys_vec, + struct vfio_region_dma_range *dma_ranges, + size_t nr_ranges); +#else +static inline int +vfio_pci_core_fill_phys_vec(struct dma_buf_phys_vec *phys_vec, + struct vfio_region_dma_range *dma_ranges, + size_t nr_ranges, phys_addr_t start, + phys_addr_t len) +{ + return -EINVAL; +} +static inline int vfio_pci_core_get_dmabuf_phys( + struct vfio_pci_core_device *vdev, struct p2pdma_provider **provider, + unsigned int region_index, struct dma_buf_phys_vec *phys_vec, + struct vfio_region_dma_range *dma_ranges, size_t nr_ranges) +{ + return -EOPNOTSUPP; +} +#endif + struct vfio_pci_core_device { struct vfio_device vdev; struct pci_dev *pdev; + const struct vfio_pci_device_ops *pci_ops; void __iomem *barmap[PCI_STD_NUM_BARS]; bool bar_mmap_supported[PCI_STD_NUM_BARS]; u8 *pci_config_map; @@ -94,6 +135,7 @@ struct vfio_pci_core_device { struct vfio_pci_core_device *sriov_pf_core_dev; struct notifier_block nb; struct rw_semaphore memory_lock; + struct list_head dmabufs; }; /* Will be exported for vfio pci drivers usage */ diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 75100bf009ba..ac2329f24141 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -14,6 +14,7 @@ #include #include +#include #define VFIO_API_VERSION 0 @@ -1478,6 +1479,33 @@ struct vfio_device_feature_bus_master { }; #define VFIO_DEVICE_FEATURE_BUS_MASTER 10 +/** + * Upon VFIO_DEVICE_FEATURE_GET create a dma_buf fd for the + * regions selected. + * + * open_flags are the typical flags passed to open(2), eg O_RDWR, O_CLOEXEC, + * etc. offset/length specify a slice of the region to create the dmabuf from. + * nr_ranges is the total number of (P2P DMA) ranges that comprise the dmabuf. + * + * flags should be 0. + * + * Return: The fd number on success, -1 and errno is set on failure. + */ +#define VFIO_DEVICE_FEATURE_DMA_BUF 11 + +struct vfio_region_dma_range { + __u64 offset; + __u64 length; +}; + +struct vfio_device_feature_dma_buf { + __u32 region_index; + __u32 open_flags; + __u32 flags; + __u32 nr_ranges; + struct vfio_region_dma_range dma_ranges[] __counted_by(nr_ranges); +}; + /* -------- API for Type1 VFIO IOMMU -------- */ /** diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 1f9ee9759426..d8b3dfc598b2 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -479,8 +479,8 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents, } break; case PCI_P2PDMA_MAP_BUS_ADDR: - sg->dma_address = pci_p2pdma_bus_addr_map(&p2pdma_state, - sg_phys(sg)); + sg->dma_address = pci_p2pdma_bus_addr_map( + p2pdma_state.mem, sg_phys(sg)); sg_dma_mark_bus_address(sg); continue; default: diff --git a/mm/hmm.c b/mm/hmm.c index 87562914670a..9bf0b831a029 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -811,7 +811,7 @@ dma_addr_t hmm_dma_map_pfn(struct device *dev, struct hmm_dma_map *map, break; case PCI_P2PDMA_MAP_BUS_ADDR: pfns[idx] |= HMM_PFN_P2PDMA_BUS | HMM_PFN_DMA_MAPPED; - return pci_p2pdma_bus_addr_map(p2pdma_state, paddr); + return pci_p2pdma_bus_addr_map(p2pdma_state->mem, paddr); default: return DMA_MAPPING_ERROR; }