Confidential-computing shared allocations need CMA backing allocations to be aligned to the architecture private/shared state-change granule size. Passing a DMA attribute into CMA would make a generic physical allocator interpret DMA and confidential-computing policy that has already been resolved by its caller.
Add an explicit minimum alignment order to dma_alloc_contiguous(). Preserve the existing size-derived alignment for ordinary callers by passing zero, and reject a request that exceeds CONFIG_CMA_ALIGNMENT. For supported requests, use the larger of the size-derived and requested orders, capped by the configured CMA alignment as before. Also distinguish preferred and required alignment for dma_alloc_from_contiguous(). Existing callers pass zero as the required alignment and retain the current clamping behavior. Callers that require a minimum alignment can request it explicitly and receive NULL when CMA cannot satisfy it. Signed-off-by: Aneesh Kumar K.V (Arm) <[email protected]> --- arch/arm/mm/dma-mapping.c | 5 +++-- drivers/iommu/dma-iommu.c | 2 +- include/linux/dma-map-ops.h | 10 ++++++---- kernel/dma/contiguous.c | 33 +++++++++++++++++++++++---------- kernel/dma/direct.c | 2 +- kernel/dma/ops_helpers.c | 2 +- kernel/dma/pool.c | 2 +- kernel/kexec_file.c | 3 ++- 8 files changed, 38 insertions(+), 21 deletions(-) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 7761099dde9e..9714fcd51941 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -398,7 +398,8 @@ static void *__alloc_from_contiguous(struct device *dev, size_t size, struct page *page; void *ptr = NULL; - page = dma_alloc_from_contiguous(dev, count, order, gfp & __GFP_NOWARN); + page = dma_alloc_from_contiguous(dev, count, order, 0, + gfp & __GFP_NOWARN); if (!page) return NULL; @@ -866,7 +867,7 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t size, unsigned long order = get_order(size); struct page *page; - page = dma_alloc_from_contiguous(dev, count, order, + page = dma_alloc_from_contiguous(dev, count, order, 0, gfp & __GFP_NOWARN); if (!page) goto error; diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 58c624513cd4..59baf2687612 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -1627,7 +1627,7 @@ static void *iommu_dma_alloc_pages(struct device *dev, size_t size, struct page *page = NULL; void *cpu_addr; - page = dma_alloc_contiguous(dev, alloc_size, gfp); + page = dma_alloc_contiguous(dev, alloc_size, gfp, 0); if (!page) page = alloc_pages_node(node, gfp, get_order(alloc_size)); if (!page) diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h index 8fae2b7deb20..5fccda7e5c69 100644 --- a/include/linux/dma-map-ops.h +++ b/include/linux/dma-map-ops.h @@ -99,10 +99,11 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, phys_addr_t limit, struct cma **res_cma, bool fixed); struct page *dma_alloc_from_contiguous(struct device *dev, size_t count, - unsigned int order, bool no_warn); + unsigned int order, unsigned int required_order, bool no_warn); bool dma_release_from_contiguous(struct device *dev, struct page *pages, int count); -struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp); +struct page *dma_alloc_contiguous(struct device *dev, size_t size, + gfp_t gfp, unsigned int align_order); void dma_free_contiguous(struct device *dev, struct page *page, size_t size); void dma_contiguous_early_fixup(phys_addr_t base, unsigned long size); @@ -125,7 +126,8 @@ static inline int dma_contiguous_reserve_area(phys_addr_t size, return -ENOSYS; } static inline struct page *dma_alloc_from_contiguous(struct device *dev, - size_t count, unsigned int order, bool no_warn) + size_t count, unsigned int order, unsigned int required_order, + bool no_warn) { return NULL; } @@ -136,7 +138,7 @@ static inline bool dma_release_from_contiguous(struct device *dev, } /* Use fallback alloc() and free() when CONFIG_DMA_CMA=n */ static inline struct page *dma_alloc_contiguous(struct device *dev, size_t size, - gfp_t gfp) + gfp_t gfp, unsigned int align_order) { return NULL; } diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index 66093460584e..a3eb3299b817 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -357,19 +357,25 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, * dma_alloc_from_contiguous() - allocate pages from contiguous area * @dev: Pointer to device for which the allocation is performed. * @count: Requested number of pages. - * @align: Requested alignment of pages (in PAGE_SIZE order). + * @align: Preferred alignment of pages (in PAGE_SIZE order). + * @required_align: Minimum required alignment (in PAGE_SIZE order). * @no_warn: Avoid printing message about failed allocation. * * This function allocates memory buffer for specified device. It uses * device specific contiguous memory area if available or the default * global one. Requires architecture specific dev_get_cma_area() helper * function. + * + * The preferred alignment is capped at CONFIG_CMA_ALIGNMENT. Return NULL + * if the required alignment exceeds this limit. A required alignment of + * zero preserves the preferred-alignment clamping behavior. */ struct page *dma_alloc_from_contiguous(struct device *dev, size_t count, - unsigned int align, bool no_warn) + unsigned int align, unsigned int required_align, bool no_warn) { - if (align > CONFIG_CMA_ALIGNMENT) - align = CONFIG_CMA_ALIGNMENT; + if (required_align > CONFIG_CMA_ALIGNMENT) + return NULL; + align = min(max(align, required_align), CONFIG_CMA_ALIGNMENT); return cma_alloc(dev_get_cma_area(dev), count, align, no_warn); } @@ -390,9 +396,14 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages, return cma_release(dev_get_cma_area(dev), pages, count); } -static struct page *cma_alloc_aligned(struct cma *cma, size_t size, gfp_t gfp) +static struct page *cma_alloc_aligned(struct cma *cma, size_t size, + gfp_t gfp, unsigned int align_order) { - unsigned int align = min(get_order(size), CONFIG_CMA_ALIGNMENT); + unsigned int align; + + if (align_order > CONFIG_CMA_ALIGNMENT) + return NULL; + align = min(max(get_order(size), align_order), CONFIG_CMA_ALIGNMENT); return cma_alloc(cma, size >> PAGE_SHIFT, align, gfp & __GFP_NOWARN); } @@ -402,6 +413,7 @@ static struct page *cma_alloc_aligned(struct cma *cma, size_t size, gfp_t gfp) * @dev: Pointer to device for which the allocation is performed. * @size: Requested allocation size. * @gfp: Allocation flags. + * @align_order: Minimum alignment as a power-of-two page order. * * tries to use device specific contiguous memory area if available, or it * tries to use per-numa cma, if the allocation fails, it will fallback to @@ -412,7 +424,8 @@ static struct page *cma_alloc_aligned(struct cma *cma, size_t size, gfp_t gfp) * there is no need to waste CMA pages for that kind; it also helps reduce * fragmentations. */ -struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) +struct page *dma_alloc_contiguous(struct device *dev, size_t size, + gfp_t gfp, unsigned int align_order) { #ifdef CONFIG_DMA_NUMA_CMA int nid = dev_to_node(dev); @@ -422,7 +435,7 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) if (!gfpflags_allow_blocking(gfp)) return NULL; if (dev->cma_area) - return cma_alloc_aligned(dev->cma_area, size, gfp); + return cma_alloc_aligned(dev->cma_area, size, gfp, align_order); if (size <= PAGE_SIZE) return NULL; @@ -431,7 +444,7 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) struct cma *cma = dma_contiguous_numa_area[nid]; struct page *page; if (cma) { - page = cma_alloc_aligned(cma, size, gfp); + page = cma_alloc_aligned(cma, size, gfp, align_order); if (page) return page; } @@ -440,7 +453,7 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) if (!dma_contiguous_default_area) return NULL; - return cma_alloc_aligned(dma_contiguous_default_area, size, gfp); + return cma_alloc_aligned(dma_contiguous_default_area, size, gfp, align_order); } /** diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index da665ca22d5c..d968a0c81e73 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -124,7 +124,7 @@ static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size, WARN_ON_ONCE(!PAGE_ALIGNED(size)); gfp |= dma_direct_optimal_gfp_mask(dev, &phys_limit); - page = dma_alloc_contiguous(dev, size, gfp); + page = dma_alloc_contiguous(dev, size, gfp, 0); if (page) { if (dma_coherent_ok(dev, page_to_phys(page), size) && (allow_highmem || !PageHighMem(page))) diff --git a/kernel/dma/ops_helpers.c b/kernel/dma/ops_helpers.c index 6b5f9208d31c..8320cc0fada5 100644 --- a/kernel/dma/ops_helpers.c +++ b/kernel/dma/ops_helpers.c @@ -66,7 +66,7 @@ struct page *dma_common_alloc_pages(struct device *dev, size_t size, struct page *page; phys_addr_t phys; - page = dma_alloc_contiguous(dev, size, gfp); + page = dma_alloc_contiguous(dev, size, gfp, 0); if (!page) page = alloc_pages_node(dev_to_node(dev), gfp, get_order(size)); if (!page) diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index 00f422a1e896..70b7f64b17ab 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c @@ -99,7 +99,7 @@ static int atomic_pool_expand(struct dma_gen_pool *dma_pool, size_t pool_size, pool_size = 1 << (PAGE_SHIFT + order); if (cma_in_zone(gfp)) page = dma_alloc_from_contiguous(NULL, 1 << order, - order, false); + order, 0, false); if (!page) page = alloc_pages(gfp | __GFP_NOWARN, order); } while (!page && order-- > 0); diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 59fb9d71e9d8..2a337ce7264e 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -682,7 +682,8 @@ static int kexec_alloc_contig(struct kexec_buf *kbuf) if (kbuf->image->type == KEXEC_TYPE_CRASH) return -EPERM; - p = dma_alloc_from_contiguous(NULL, nr_pages, get_order(kbuf->buf_align), true); + p = dma_alloc_from_contiguous(NULL, nr_pages, + get_order(kbuf->buf_align), 0, true); if (!p) return -ENOMEM; -- 2.43.0
