Several IOMMU drivers have a bypass mode where they can use a direct mapping if the devices DMA mask is large enough. Add generic support to the core dma-mapping code to do that to switch those drivers to a common solution.
Signed-off-by: Christoph Hellwig <h...@lst.de> --- include/linux/device.h | 6 ++++++ include/linux/dma-mapping.h | 30 ++++++++++++++++++------------ kernel/dma/mapping.c | 36 +++++++++++++++++++++++++++--------- 3 files changed, 51 insertions(+), 21 deletions(-) diff --git a/include/linux/device.h b/include/linux/device.h index 0cd7c647c16c..09be8bb2c4a6 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -525,6 +525,11 @@ struct dev_links_info { * sync_state() callback. * @dma_coherent: this particular device is dma coherent, even if the * architecture supports non-coherent devices. + * @dma_ops_bypass: If set to %true then the dma_ops are bypassed for the + * streaming DMA operations (->map_* / ->unmap_* / ->sync_*), + * and optionall (if the coherent mask is large enough) also + * for dma allocations. This flag is managed by the dma ops + * instance from ->dma_supported. * * At the lowest level, every device in a Linux system is represented by an * instance of struct device. The device structure contains the information @@ -625,6 +630,7 @@ struct device { defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL) bool dma_coherent:1; #endif + bool dma_ops_bypass : 1; }; static inline struct device *kobj_to_dev(struct kobject *kobj) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 330ad58fbf4d..c3af0cf5e435 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -188,9 +188,15 @@ static inline int dma_mmap_from_global_coherent(struct vm_area_struct *vma, } #endif /* CONFIG_DMA_DECLARE_COHERENT */ -static inline bool dma_is_direct(const struct dma_map_ops *ops) +/* + * Check if the devices uses a direct mapping for streaming DMA operations. + * This allows IOMMU drivers to set a bypass mode if the DMA mask is large + * enough. + */ +static inline bool dma_map_direct(struct device *dev, + const struct dma_map_ops *ops) { - return likely(!ops); + return likely(!ops) || dev->dma_ops_bypass; } /* @@ -279,7 +285,7 @@ static inline dma_addr_t dma_map_page_attrs(struct device *dev, dma_addr_t addr; BUG_ON(!valid_dma_direction(dir)); - if (dma_is_direct(ops)) + if (dma_map_direct(dev, ops)) addr = dma_direct_map_page(dev, page, offset, size, dir, attrs); else addr = ops->map_page(dev, page, offset, size, dir, attrs); @@ -294,7 +300,7 @@ static inline void dma_unmap_page_attrs(struct device *dev, dma_addr_t addr, const struct dma_map_ops *ops = get_dma_ops(dev); BUG_ON(!valid_dma_direction(dir)); - if (dma_is_direct(ops)) + if (dma_map_direct(dev, ops)) dma_direct_unmap_page(dev, addr, size, dir, attrs); else if (ops->unmap_page) ops->unmap_page(dev, addr, size, dir, attrs); @@ -313,7 +319,7 @@ static inline int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int ents; BUG_ON(!valid_dma_direction(dir)); - if (dma_is_direct(ops)) + if (dma_map_direct(dev, ops)) ents = dma_direct_map_sg(dev, sg, nents, dir, attrs); else ents = ops->map_sg(dev, sg, nents, dir, attrs); @@ -331,7 +337,7 @@ static inline void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg BUG_ON(!valid_dma_direction(dir)); debug_dma_unmap_sg(dev, sg, nents, dir); - if (dma_is_direct(ops)) + if (dma_map_direct(dev, ops)) dma_direct_unmap_sg(dev, sg, nents, dir, attrs); else if (ops->unmap_sg) ops->unmap_sg(dev, sg, nents, dir, attrs); @@ -352,7 +358,7 @@ static inline dma_addr_t dma_map_resource(struct device *dev, if (WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr)))) return DMA_MAPPING_ERROR; - if (dma_is_direct(ops)) + if (dma_map_direct(dev, ops)) addr = dma_direct_map_resource(dev, phys_addr, size, dir, attrs); else if (ops->map_resource) addr = ops->map_resource(dev, phys_addr, size, dir, attrs); @@ -368,7 +374,7 @@ static inline void dma_unmap_resource(struct device *dev, dma_addr_t addr, const struct dma_map_ops *ops = get_dma_ops(dev); BUG_ON(!valid_dma_direction(dir)); - if (!dma_is_direct(ops) && ops->unmap_resource) + if (!dma_map_direct(dev, ops) && ops->unmap_resource) ops->unmap_resource(dev, addr, size, dir, attrs); debug_dma_unmap_resource(dev, addr, size, dir); } @@ -380,7 +386,7 @@ static inline void dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr, const struct dma_map_ops *ops = get_dma_ops(dev); BUG_ON(!valid_dma_direction(dir)); - if (dma_is_direct(ops)) + if (dma_map_direct(dev, ops)) dma_direct_sync_single_for_cpu(dev, addr, size, dir); else if (ops->sync_single_for_cpu) ops->sync_single_for_cpu(dev, addr, size, dir); @@ -394,7 +400,7 @@ static inline void dma_sync_single_for_device(struct device *dev, const struct dma_map_ops *ops = get_dma_ops(dev); BUG_ON(!valid_dma_direction(dir)); - if (dma_is_direct(ops)) + if (dma_map_direct(dev, ops)) dma_direct_sync_single_for_device(dev, addr, size, dir); else if (ops->sync_single_for_device) ops->sync_single_for_device(dev, addr, size, dir); @@ -408,7 +414,7 @@ dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, const struct dma_map_ops *ops = get_dma_ops(dev); BUG_ON(!valid_dma_direction(dir)); - if (dma_is_direct(ops)) + if (dma_map_direct(dev, ops)) dma_direct_sync_sg_for_cpu(dev, sg, nelems, dir); else if (ops->sync_sg_for_cpu) ops->sync_sg_for_cpu(dev, sg, nelems, dir); @@ -422,7 +428,7 @@ dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, const struct dma_map_ops *ops = get_dma_ops(dev); BUG_ON(!valid_dma_direction(dir)); - if (dma_is_direct(ops)) + if (dma_map_direct(dev, ops)) dma_direct_sync_sg_for_device(dev, sg, nelems, dir); else if (ops->sync_sg_for_device) ops->sync_sg_for_device(dev, sg, nelems, dir); diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 12ff766ec1fa..fdea45574345 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -105,6 +105,24 @@ void *dmam_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, } EXPORT_SYMBOL(dmam_alloc_attrs); +static bool dma_alloc_direct(struct device *dev, const struct dma_map_ops *ops) +{ + if (!ops) + return true; + + /* + * Allows IOMMU drivers to bypass dynamic translations if the DMA mask + * is large enough. + */ + if (dev->dma_ops_bypass) { + if (min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit) >= + dma_direct_get_required_mask(dev)) + return true; + } + + return false; +} + /* * Create scatter-list for the already allocated DMA buffer. */ @@ -138,7 +156,7 @@ int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt, { const struct dma_map_ops *ops = get_dma_ops(dev); - if (dma_is_direct(ops)) + if (dma_alloc_direct(dev, ops)) return dma_direct_get_sgtable(dev, sgt, cpu_addr, dma_addr, size, attrs); if (!ops->get_sgtable) @@ -206,7 +224,7 @@ bool dma_can_mmap(struct device *dev) { const struct dma_map_ops *ops = get_dma_ops(dev); - if (dma_is_direct(ops)) + if (dma_alloc_direct(dev, ops)) return dma_direct_can_mmap(dev); return ops->mmap != NULL; } @@ -231,7 +249,7 @@ int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma, { const struct dma_map_ops *ops = get_dma_ops(dev); - if (dma_is_direct(ops)) + if (dma_alloc_direct(dev, ops)) return dma_direct_mmap(dev, vma, cpu_addr, dma_addr, size, attrs); if (!ops->mmap) @@ -244,7 +262,7 @@ u64 dma_get_required_mask(struct device *dev) { const struct dma_map_ops *ops = get_dma_ops(dev); - if (dma_is_direct(ops)) + if (dma_map_direct(dev, ops)) return dma_direct_get_required_mask(dev); if (ops->get_required_mask) return ops->get_required_mask(dev); @@ -275,7 +293,7 @@ void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, /* let the implementation decide on the zone to allocate from: */ flag &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM); - if (dma_is_direct(ops)) + if (dma_alloc_direct(dev, ops)) cpu_addr = dma_direct_alloc(dev, size, dma_handle, flag, attrs); else if (ops->alloc) cpu_addr = ops->alloc(dev, size, dma_handle, flag, attrs); @@ -307,7 +325,7 @@ void dma_free_attrs(struct device *dev, size_t size, void *cpu_addr, return; debug_dma_free_coherent(dev, size, cpu_addr, dma_handle); - if (dma_is_direct(ops)) + if (dma_alloc_direct(dev, ops)) dma_direct_free(dev, size, cpu_addr, dma_handle, attrs); else if (ops->free) ops->free(dev, size, cpu_addr, dma_handle, attrs); @@ -318,7 +336,7 @@ int dma_supported(struct device *dev, u64 mask) { const struct dma_map_ops *ops = get_dma_ops(dev); - if (dma_is_direct(ops)) + if (!ops) return dma_direct_supported(dev, mask); if (!ops->dma_supported) return 1; @@ -374,7 +392,7 @@ void dma_cache_sync(struct device *dev, void *vaddr, size_t size, BUG_ON(!valid_dma_direction(dir)); - if (dma_is_direct(ops)) + if (dma_alloc_direct(dev, ops)) arch_dma_cache_sync(dev, vaddr, size, dir); else if (ops->cache_sync) ops->cache_sync(dev, vaddr, size, dir); @@ -386,7 +404,7 @@ size_t dma_max_mapping_size(struct device *dev) const struct dma_map_ops *ops = get_dma_ops(dev); size_t size = SIZE_MAX; - if (dma_is_direct(ops)) + if (dma_map_direct(dev, ops)) size = dma_direct_max_mapping_size(dev); else if (ops && ops->max_mapping_size) size = ops->max_mapping_size(dev); -- 2.25.1