From 393cf700e6242032fbad51b248111ab6740ce8ad Mon Sep 17 00:00:00 2001 From: Leon Romanovsky Date: Mon, 5 May 2025 10:01:42 +0300 Subject: dma-mapping: Provide an interface to allow allocate IOVA The existing .map_pages() callback provides both allocating of IOVA and linking DMA pages. That combination works great for most of the callers who use it in control paths, but is less effective in fast paths where there may be multiple calls to map_page(). These advanced callers already manage their data in some sort of database and can perform IOVA allocation in advance, leaving range linkage operation to be in fast path. Provide an interface to allocate/deallocate IOVA and next patch link/unlink DMA ranges to that specific IOVA. In the new API a DMA mapping transaction is identified by a struct dma_iova_state, which holds some recomputed information for the transaction which does not change for each page being mapped, so add a check if IOVA can be used for the specific transaction. The API is exported from dma-iommu as it is the only implementation supported, the namespace is clearly different from iommu_* functions which are not allowed to be used. This code layout allows us to save function call per API call used in datapath as well as a lot of boilerplate code. Reviewed-by: Christoph Hellwig Tested-by: Jens Axboe Reviewed-by: Luis Chamberlain Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski --- include/linux/dma-mapping.h | 48 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) (limited to 'include/linux/dma-mapping.h') diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index b79925b1c433..de7f73810d54 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -72,6 +72,22 @@ #define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1)) +struct dma_iova_state { + dma_addr_t addr; + u64 __size; +}; + +/* + * Use the high bit to mark if we used swiotlb for one or more ranges. + */ +#define DMA_IOVA_USE_SWIOTLB (1ULL << 63) + +static inline size_t dma_iova_size(struct dma_iova_state *state) +{ + /* Casting is needed for 32-bits systems */ + return (size_t)(state->__size & ~DMA_IOVA_USE_SWIOTLB); +} + #ifdef CONFIG_DMA_API_DEBUG void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr); void debug_dma_map_single(struct device *dev, const void *addr, @@ -277,6 +293,38 @@ static inline int dma_mmap_noncontiguous(struct device *dev, } #endif /* CONFIG_HAS_DMA */ +#ifdef CONFIG_IOMMU_DMA +/** + * dma_use_iova - check if the IOVA API is used for this state + * @state: IOVA state + * + * Return %true if the DMA transfers uses the dma_iova_*() calls or %false if + * they can't be used. + */ +static inline bool dma_use_iova(struct dma_iova_state *state) +{ + return state->__size != 0; +} + +bool dma_iova_try_alloc(struct device *dev, struct dma_iova_state *state, + phys_addr_t phys, size_t size); +void dma_iova_free(struct device *dev, struct dma_iova_state *state); +#else /* CONFIG_IOMMU_DMA */ +static inline bool dma_use_iova(struct dma_iova_state *state) +{ + return false; +} +static inline bool dma_iova_try_alloc(struct device *dev, + struct dma_iova_state *state, phys_addr_t phys, size_t size) +{ + return false; +} +static inline void dma_iova_free(struct device *dev, + struct dma_iova_state *state) +{ +} +#endif /* CONFIG_IOMMU_DMA */ + #if defined(CONFIG_HAS_DMA) && defined(CONFIG_DMA_NEED_SYNC) void __dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr, size_t size, enum dma_data_direction dir); -- cgit v1.2.3 From 433a76207dcf5facc0183acb790f6e8398585258 Mon Sep 17 00:00:00 2001 From: Leon Romanovsky Date: Mon, 5 May 2025 10:01:44 +0300 Subject: dma-mapping: Implement link/unlink ranges API Introduce new DMA APIs to perform DMA linkage of buffers in layers higher than DMA. In proposed API, the callers will perform the following steps. In map path: if (dma_can_use_iova(...)) dma_iova_alloc() for (page in range) dma_iova_link_next(...) dma_iova_sync(...) else /* Fallback to legacy map pages */ for (all pages) dma_map_page(...) In unmap path: if (dma_can_use_iova(...)) dma_iova_destroy() else for (all pages) dma_unmap_page(...) Reviewed-by: Christoph Hellwig Tested-by: Jens Axboe Reviewed-by: Luis Chamberlain Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski --- drivers/iommu/dma-iommu.c | 275 +++++++++++++++++++++++++++++++++++++++++++- include/linux/dma-mapping.h | 32 ++++++ 2 files changed, 306 insertions(+), 1 deletion(-) (limited to 'include/linux/dma-mapping.h') diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index d2c298083e0a..1569efe71118 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -1175,6 +1175,17 @@ static phys_addr_t iommu_dma_map_swiotlb(struct device *dev, phys_addr_t phys, return phys; } +/* + * Checks if a physical buffer has unaligned boundaries with respect to + * the IOMMU granule. Returns non-zero if either the start or end + * address is not aligned to the granule boundary. + */ +static inline size_t iova_unaligned(struct iova_domain *iovad, phys_addr_t phys, + size_t size) +{ + return iova_offset(iovad, phys | size); +} + dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page, unsigned long offset, size_t size, enum dma_data_direction dir, unsigned long attrs) @@ -1192,7 +1203,7 @@ dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page, * we don't need to use a bounce page. */ if (dev_use_swiotlb(dev, size, dir) && - iova_offset(iovad, phys | size)) { + iova_unaligned(iovad, phys, size)) { phys = iommu_dma_map_swiotlb(dev, phys, size, dir, attrs); if (phys == (phys_addr_t)DMA_MAPPING_ERROR) return DMA_MAPPING_ERROR; @@ -1818,6 +1829,268 @@ void dma_iova_free(struct device *dev, struct dma_iova_state *state) } EXPORT_SYMBOL_GPL(dma_iova_free); +static int __dma_iova_link(struct device *dev, dma_addr_t addr, + phys_addr_t phys, size_t size, enum dma_data_direction dir, + unsigned long attrs) +{ + bool coherent = dev_is_dma_coherent(dev); + + if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) + arch_sync_dma_for_device(phys, size, dir); + + return iommu_map_nosync(iommu_get_dma_domain(dev), addr, phys, size, + dma_info_to_prot(dir, coherent, attrs), GFP_ATOMIC); +} + +static int iommu_dma_iova_bounce_and_link(struct device *dev, dma_addr_t addr, + phys_addr_t phys, size_t bounce_len, + enum dma_data_direction dir, unsigned long attrs, + size_t iova_start_pad) +{ + struct iommu_domain *domain = iommu_get_dma_domain(dev); + struct iova_domain *iovad = &domain->iova_cookie->iovad; + phys_addr_t bounce_phys; + int error; + + bounce_phys = iommu_dma_map_swiotlb(dev, phys, bounce_len, dir, attrs); + if (bounce_phys == DMA_MAPPING_ERROR) + return -ENOMEM; + + error = __dma_iova_link(dev, addr - iova_start_pad, + bounce_phys - iova_start_pad, + iova_align(iovad, bounce_len), dir, attrs); + if (error) + swiotlb_tbl_unmap_single(dev, bounce_phys, bounce_len, dir, + attrs); + return error; +} + +static int iommu_dma_iova_link_swiotlb(struct device *dev, + struct dma_iova_state *state, phys_addr_t phys, size_t offset, + size_t size, enum dma_data_direction dir, unsigned long attrs) +{ + struct iommu_domain *domain = iommu_get_dma_domain(dev); + struct iommu_dma_cookie *cookie = domain->iova_cookie; + struct iova_domain *iovad = &cookie->iovad; + size_t iova_start_pad = iova_offset(iovad, phys); + size_t iova_end_pad = iova_offset(iovad, phys + size); + dma_addr_t addr = state->addr + offset; + size_t mapped = 0; + int error; + + if (iova_start_pad) { + size_t bounce_len = min(size, iovad->granule - iova_start_pad); + + error = iommu_dma_iova_bounce_and_link(dev, addr, phys, + bounce_len, dir, attrs, iova_start_pad); + if (error) + return error; + state->__size |= DMA_IOVA_USE_SWIOTLB; + + mapped += bounce_len; + size -= bounce_len; + if (!size) + return 0; + } + + size -= iova_end_pad; + error = __dma_iova_link(dev, addr + mapped, phys + mapped, size, dir, + attrs); + if (error) + goto out_unmap; + mapped += size; + + if (iova_end_pad) { + error = iommu_dma_iova_bounce_and_link(dev, addr + mapped, + phys + mapped, iova_end_pad, dir, attrs, 0); + if (error) + goto out_unmap; + state->__size |= DMA_IOVA_USE_SWIOTLB; + } + + return 0; + +out_unmap: + dma_iova_unlink(dev, state, 0, mapped, dir, attrs); + return error; +} + +/** + * dma_iova_link - Link a range of IOVA space + * @dev: DMA device + * @state: IOVA state + * @phys: physical address to link + * @offset: offset into the IOVA state to map into + * @size: size of the buffer + * @dir: DMA direction + * @attrs: attributes of mapping properties + * + * Link a range of IOVA space for the given IOVA state without IOTLB sync. + * This function is used to link multiple physical addresses in contiguous + * IOVA space without performing costly IOTLB sync. + * + * The caller is responsible to call to dma_iova_sync() to sync IOTLB at + * the end of linkage. + */ +int dma_iova_link(struct device *dev, struct dma_iova_state *state, + phys_addr_t phys, size_t offset, size_t size, + enum dma_data_direction dir, unsigned long attrs) +{ + struct iommu_domain *domain = iommu_get_dma_domain(dev); + struct iommu_dma_cookie *cookie = domain->iova_cookie; + struct iova_domain *iovad = &cookie->iovad; + size_t iova_start_pad = iova_offset(iovad, phys); + + if (WARN_ON_ONCE(iova_start_pad && offset > 0)) + return -EIO; + + if (dev_use_swiotlb(dev, size, dir) && + iova_unaligned(iovad, phys, size)) + return iommu_dma_iova_link_swiotlb(dev, state, phys, offset, + size, dir, attrs); + + return __dma_iova_link(dev, state->addr + offset - iova_start_pad, + phys - iova_start_pad, + iova_align(iovad, size + iova_start_pad), dir, attrs); +} +EXPORT_SYMBOL_GPL(dma_iova_link); + +/** + * dma_iova_sync - Sync IOTLB + * @dev: DMA device + * @state: IOVA state + * @offset: offset into the IOVA state to sync + * @size: size of the buffer + * + * Sync IOTLB for the given IOVA state. This function should be called on + * the IOVA-contiguous range created by one ore more dma_iova_link() calls + * to sync the IOTLB. + */ +int dma_iova_sync(struct device *dev, struct dma_iova_state *state, + size_t offset, size_t size) +{ + struct iommu_domain *domain = iommu_get_dma_domain(dev); + struct iommu_dma_cookie *cookie = domain->iova_cookie; + struct iova_domain *iovad = &cookie->iovad; + dma_addr_t addr = state->addr + offset; + size_t iova_start_pad = iova_offset(iovad, addr); + + return iommu_sync_map(domain, addr - iova_start_pad, + iova_align(iovad, size + iova_start_pad)); +} +EXPORT_SYMBOL_GPL(dma_iova_sync); + +static void iommu_dma_iova_unlink_range_slow(struct device *dev, + dma_addr_t addr, size_t size, enum dma_data_direction dir, + unsigned long attrs) +{ + struct iommu_domain *domain = iommu_get_dma_domain(dev); + struct iommu_dma_cookie *cookie = domain->iova_cookie; + struct iova_domain *iovad = &cookie->iovad; + size_t iova_start_pad = iova_offset(iovad, addr); + dma_addr_t end = addr + size; + + do { + phys_addr_t phys; + size_t len; + + phys = iommu_iova_to_phys(domain, addr); + if (WARN_ON(!phys)) + /* Something very horrible happen here */ + return; + + len = min_t(size_t, + end - addr, iovad->granule - iova_start_pad); + + if (!dev_is_dma_coherent(dev) && + !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) + arch_sync_dma_for_cpu(phys, len, dir); + + swiotlb_tbl_unmap_single(dev, phys, len, dir, attrs); + + addr += len; + iova_start_pad = 0; + } while (addr < end); +} + +static void __iommu_dma_iova_unlink(struct device *dev, + struct dma_iova_state *state, size_t offset, size_t size, + enum dma_data_direction dir, unsigned long attrs, + bool free_iova) +{ + struct iommu_domain *domain = iommu_get_dma_domain(dev); + struct iommu_dma_cookie *cookie = domain->iova_cookie; + struct iova_domain *iovad = &cookie->iovad; + dma_addr_t addr = state->addr + offset; + size_t iova_start_pad = iova_offset(iovad, addr); + struct iommu_iotlb_gather iotlb_gather; + size_t unmapped; + + if ((state->__size & DMA_IOVA_USE_SWIOTLB) || + (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))) + iommu_dma_iova_unlink_range_slow(dev, addr, size, dir, attrs); + + iommu_iotlb_gather_init(&iotlb_gather); + iotlb_gather.queued = free_iova && READ_ONCE(cookie->fq_domain); + + size = iova_align(iovad, size + iova_start_pad); + addr -= iova_start_pad; + unmapped = iommu_unmap_fast(domain, addr, size, &iotlb_gather); + WARN_ON(unmapped != size); + + if (!iotlb_gather.queued) + iommu_iotlb_sync(domain, &iotlb_gather); + if (free_iova) + iommu_dma_free_iova(domain, addr, size, &iotlb_gather); +} + +/** + * dma_iova_unlink - Unlink a range of IOVA space + * @dev: DMA device + * @state: IOVA state + * @offset: offset into the IOVA state to unlink + * @size: size of the buffer + * @dir: DMA direction + * @attrs: attributes of mapping properties + * + * Unlink a range of IOVA space for the given IOVA state. + */ +void dma_iova_unlink(struct device *dev, struct dma_iova_state *state, + size_t offset, size_t size, enum dma_data_direction dir, + unsigned long attrs) +{ + __iommu_dma_iova_unlink(dev, state, offset, size, dir, attrs, false); +} +EXPORT_SYMBOL_GPL(dma_iova_unlink); + +/** + * dma_iova_destroy - Finish a DMA mapping transaction + * @dev: DMA device + * @state: IOVA state + * @mapped_len: number of bytes to unmap + * @dir: DMA direction + * @attrs: attributes of mapping properties + * + * Unlink the IOVA range up to @mapped_len and free the entire IOVA space. The + * range of IOVA from dma_addr to @mapped_len must all be linked, and be the + * only linked IOVA in state. + */ +void dma_iova_destroy(struct device *dev, struct dma_iova_state *state, + size_t mapped_len, enum dma_data_direction dir, + unsigned long attrs) +{ + if (mapped_len) + __iommu_dma_iova_unlink(dev, state, 0, mapped_len, dir, attrs, + true); + else + /* + * We can be here if first call to dma_iova_link() failed and + * there is nothing to unlink, so let's be more clear. + */ + dma_iova_free(dev, state); +} +EXPORT_SYMBOL_GPL(dma_iova_destroy); + void iommu_setup_dma_ops(struct device *dev) { struct iommu_domain *domain = iommu_get_domain_for_dev(dev); diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index de7f73810d54..a71e110f1e9d 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -309,6 +309,17 @@ static inline bool dma_use_iova(struct dma_iova_state *state) bool dma_iova_try_alloc(struct device *dev, struct dma_iova_state *state, phys_addr_t phys, size_t size); void dma_iova_free(struct device *dev, struct dma_iova_state *state); +void dma_iova_destroy(struct device *dev, struct dma_iova_state *state, + size_t mapped_len, enum dma_data_direction dir, + unsigned long attrs); +int dma_iova_sync(struct device *dev, struct dma_iova_state *state, + size_t offset, size_t size); +int dma_iova_link(struct device *dev, struct dma_iova_state *state, + phys_addr_t phys, size_t offset, size_t size, + enum dma_data_direction dir, unsigned long attrs); +void dma_iova_unlink(struct device *dev, struct dma_iova_state *state, + size_t offset, size_t size, enum dma_data_direction dir, + unsigned long attrs); #else /* CONFIG_IOMMU_DMA */ static inline bool dma_use_iova(struct dma_iova_state *state) { @@ -323,6 +334,27 @@ static inline void dma_iova_free(struct device *dev, struct dma_iova_state *state) { } +static inline void dma_iova_destroy(struct device *dev, + struct dma_iova_state *state, size_t mapped_len, + enum dma_data_direction dir, unsigned long attrs) +{ +} +static inline int dma_iova_sync(struct device *dev, + struct dma_iova_state *state, size_t offset, size_t size) +{ + return -EOPNOTSUPP; +} +static inline int dma_iova_link(struct device *dev, + struct dma_iova_state *state, phys_addr_t phys, size_t offset, + size_t size, enum dma_data_direction dir, unsigned long attrs) +{ + return -EOPNOTSUPP; +} +static inline void dma_iova_unlink(struct device *dev, + struct dma_iova_state *state, size_t offset, size_t size, + enum dma_data_direction dir, unsigned long attrs) +{ +} #endif /* CONFIG_IOMMU_DMA */ #if defined(CONFIG_HAS_DMA) && defined(CONFIG_DMA_NEED_SYNC) -- cgit v1.2.3 From 5f3b133a23c545272b6bc1e818a5a35e1ca84b1e Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 5 May 2025 10:01:45 +0300 Subject: dma-mapping: add a dma_need_unmap helper Add helper that allows a driver to skip calling dma_unmap_* if the DMA layer can guarantee that they are no-nops. Signed-off-by: Christoph Hellwig Tested-by: Jens Axboe Reviewed-by: Luis Chamberlain Signed-off-by: Leon Romanovsky Signed-off-by: Marek Szyprowski --- include/linux/dma-mapping.h | 5 +++++ kernel/dma/mapping.c | 18 ++++++++++++++++++ 2 files changed, 23 insertions(+) (limited to 'include/linux/dma-mapping.h') diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index a71e110f1e9d..d2f358c5a25d 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -406,6 +406,7 @@ static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr) { return dma_dev_need_sync(dev) ? __dma_need_sync(dev, dma_addr) : false; } +bool dma_need_unmap(struct device *dev); #else /* !CONFIG_HAS_DMA || !CONFIG_DMA_NEED_SYNC */ static inline bool dma_dev_need_sync(const struct device *dev) { @@ -431,6 +432,10 @@ static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr) { return false; } +static inline bool dma_need_unmap(struct device *dev) +{ + return false; +} #endif /* !CONFIG_HAS_DMA || !CONFIG_DMA_NEED_SYNC */ struct page *dma_alloc_pages(struct device *dev, size_t size, diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index cda127027e48..3c3204ad2839 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -443,6 +443,24 @@ bool __dma_need_sync(struct device *dev, dma_addr_t dma_addr) } EXPORT_SYMBOL_GPL(__dma_need_sync); +/** + * dma_need_unmap - does this device need dma_unmap_* operations + * @dev: device to check + * + * If this function returns %false, drivers can skip calling dma_unmap_* after + * finishing an I/O. This function must be called after all mappings that might + * need to be unmapped have been performed. + */ +bool dma_need_unmap(struct device *dev) +{ + if (!dma_map_direct(dev, get_dma_ops(dev))) + return true; + if (!dev->dma_skip_sync) + return true; + return IS_ENABLED(CONFIG_DMA_API_DEBUG); +} +EXPORT_SYMBOL_GPL(dma_need_unmap); + static void dma_setup_need_sync(struct device *dev) { const struct dma_map_ops *ops = get_dma_ops(dev); -- cgit v1.2.3