Messages in this thread Patch in this message |  | | Date | Tue, 5 May 2026 00:27:37 +0000 | | Subject | [RFC PATCH 4/4] dma-mapping: Add API to preserve/restore DMA allocation | | From | Samiullah Khawaja <> |
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Add new DMA APIs that allow preserving/restoring DMA allocations across live update.
Signed-off-by: Samiullah Khawaja <skhawaja@google.com> --- include/linux/dma-mapping.h | 50 +++++++++++++++++++++++++++++++++++ kernel/dma/mapping.c | 52 +++++++++++++++++++++++++++++++++++++ 2 files changed, 102 insertions(+)
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index db8ab24a54f4..3756fc15467b 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -210,6 +210,15 @@ void *dma_vmap_noncontiguous(struct device *dev, size_t size, void dma_vunmap_noncontiguous(struct device *dev, void *vaddr); int dma_mmap_noncontiguous(struct device *dev, struct vm_area_struct *vma, size_t size, struct sg_table *sgt); +#ifdef CONFIG_DMA_LIVEUPDATE +int dma_preserve_allocation_attrs(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, + unsigned long attrs, u64 *state); +void dma_unpreserve_allocation(struct device *dev, u64 state); +void *dma_restore_allocation_attrs(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp, + unsigned long attrs, u64 state); +#endif #else /* CONFIG_HAS_DMA */ static inline dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page, size_t offset, size_t size, @@ -496,6 +505,26 @@ static inline bool dma_need_unmap(struct device *dev) } #endif /* !CONFIG_HAS_DMA || !CONFIG_DMA_NEED_SYNC */ +#if !defined(CONFIG_DMA_LIVEUPDATE) || !defined(CONFIG_HAS_DMA) +static inline int dma_preserve_allocation_attrs(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, + unsigned long attrs, u64 *state) +{ + return -EOPNOTSUPP; +} + +static inline void dma_unpreserve_allocation(struct device *dev, u64 state) +{ +} + +static inline void *dma_restore_allocation_attrs(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp, + unsigned long attrs, u64 state) +{ + return NULL; +} +#endif + struct page *dma_alloc_pages(struct device *dev, size_t size, dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp); void dma_free_pages(struct device *dev, size_t size, struct page *page, @@ -618,6 +647,27 @@ static inline void *dma_alloc_coherent(struct device *dev, size_t size, (gfp & __GFP_NOWARN) ? DMA_ATTR_NO_WARN : 0); } +static inline int dma_preserve_coherent_allocation(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, u64 *state) +{ + return dma_preserve_allocation_attrs(dev, cpu_addr, size, + dma_handle, 0, state); +} + +static inline void dma_unpreserve_coherent_allocation(struct device *dev, u64 state) +{ + dma_unpreserve_allocation(dev, state); +} + +static inline void *dma_restore_coherent_allocation(struct device *dev, size_t size, + dma_addr_t *dma_handle, + gfp_t gfp, u64 state) +{ + return dma_restore_allocation_attrs(dev, size, dma_handle, gfp, + (gfp & __GFP_NOWARN) ? DMA_ATTR_NO_WARN : 0, + state); +} + static inline void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_handle) { diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 23ed8eb9233e..c315b74a0884 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -12,6 +12,8 @@ #include <linux/gfp.h> #include <linux/iommu-dma.h> #include <linux/kmsan.h> +#include <linux/kexec_handover.h> +#include <linux/kho/abi/dma_alloc.h> #include <linux/of_device.h> #include <linux/slab.h> #include <linux/vmalloc.h> @@ -628,6 +630,56 @@ u64 dma_get_required_mask(struct device *dev) } EXPORT_SYMBOL_GPL(dma_get_required_mask); +#ifdef CONFIG_DMA_LIVEUPDATE +int dma_preserve_allocation_attrs(struct device *dev, void *cpu_addr, + size_t size, dma_addr_t dma_handle, + unsigned long attrs, u64 *state) +{ + const struct dma_map_ops *ops = get_dma_ops(dev); + +#ifdef CONFIG_DMA_DECLARE_COHERENT + return -EOPNOTSUPP; +#endif + + if (dma_alloc_direct(dev, ops)) + return dma_direct_preserve_allocation(dev, cpu_addr, size, + dma_handle, attrs, + state); + + return -EOPNOTSUPP; +} +EXPORT_SYMBOL(dma_preserve_allocation_attrs); + +void dma_unpreserve_allocation(struct device *dev, u64 state) +{ + const struct dma_map_ops *ops = get_dma_ops(dev); + + if (dma_alloc_direct(dev, ops)) + dma_direct_unpreserve_allocation(dev, state); +} +EXPORT_SYMBOL(dma_unpreserve_allocation); + +void *dma_restore_allocation_attrs(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp, + unsigned long attrs, u64 state) +{ + const struct dma_map_ops *ops = get_dma_ops(dev); + + WARN_ON_ONCE(!dev->coherent_dma_mask); + +#ifdef CONFIG_DMA_DECLARE_COHERENT + return NULL; +#endif + + if (dma_alloc_direct(dev, ops)) + return dma_direct_restore_allocation(dev, size, dma_handle, + gfp, attrs, state); + + return NULL; +} +EXPORT_SYMBOL(dma_restore_allocation_attrs); +#endif + void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t flag, unsigned long attrs) { -- 2.54.0.545.g6539524ca2-goog
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