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dma-remap: separate DMA atomic pools from direct remap code
DMA atomic pools will be needed beyond only CONFIG_DMA_DIRECT_REMAP so separate them out into their own file. This also adds a new Kconfig option that can be subsequently used for options, such as CONFIG_AMD_MEM_ENCRYPT, that will utilize the coherent pools but do not have a dependency on direct remapping. For this patch alone, there is no functional change introduced. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: David Rientjes <rientjes@google.com> [hch: fixup copyrights and remove unused includes] Signed-off-by: Christoph Hellwig <hch@lst.de>
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David Rientjes
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Christoph Hellwig
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Apr 20, 2020
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,123 @@ | ||
| // SPDX-License-Identifier: GPL-2.0 | ||
| /* | ||
| * Copyright (C) 2012 ARM Ltd. | ||
| * Copyright (C) 2020 Google LLC | ||
| */ | ||
| #include <linux/dma-direct.h> | ||
| #include <linux/dma-noncoherent.h> | ||
| #include <linux/dma-contiguous.h> | ||
| #include <linux/init.h> | ||
| #include <linux/genalloc.h> | ||
| #include <linux/slab.h> | ||
|
|
||
| static struct gen_pool *atomic_pool __ro_after_init; | ||
|
|
||
| #define DEFAULT_DMA_COHERENT_POOL_SIZE SZ_256K | ||
| static size_t atomic_pool_size __initdata = DEFAULT_DMA_COHERENT_POOL_SIZE; | ||
|
|
||
| static int __init early_coherent_pool(char *p) | ||
| { | ||
| atomic_pool_size = memparse(p, &p); | ||
| return 0; | ||
| } | ||
| early_param("coherent_pool", early_coherent_pool); | ||
|
|
||
| static gfp_t dma_atomic_pool_gfp(void) | ||
| { | ||
| if (IS_ENABLED(CONFIG_ZONE_DMA)) | ||
| return GFP_DMA; | ||
| if (IS_ENABLED(CONFIG_ZONE_DMA32)) | ||
| return GFP_DMA32; | ||
| return GFP_KERNEL; | ||
| } | ||
|
|
||
| static int __init dma_atomic_pool_init(void) | ||
| { | ||
| unsigned int pool_size_order = get_order(atomic_pool_size); | ||
| unsigned long nr_pages = atomic_pool_size >> PAGE_SHIFT; | ||
| struct page *page; | ||
| void *addr; | ||
| int ret; | ||
|
|
||
| if (dev_get_cma_area(NULL)) | ||
| page = dma_alloc_from_contiguous(NULL, nr_pages, | ||
| pool_size_order, false); | ||
| else | ||
| page = alloc_pages(dma_atomic_pool_gfp(), pool_size_order); | ||
| if (!page) | ||
| goto out; | ||
|
|
||
| arch_dma_prep_coherent(page, atomic_pool_size); | ||
|
|
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| atomic_pool = gen_pool_create(PAGE_SHIFT, -1); | ||
| if (!atomic_pool) | ||
| goto free_page; | ||
|
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||
| addr = dma_common_contiguous_remap(page, atomic_pool_size, | ||
| pgprot_dmacoherent(PAGE_KERNEL), | ||
| __builtin_return_address(0)); | ||
| if (!addr) | ||
| goto destroy_genpool; | ||
|
|
||
| ret = gen_pool_add_virt(atomic_pool, (unsigned long)addr, | ||
| page_to_phys(page), atomic_pool_size, -1); | ||
| if (ret) | ||
| goto remove_mapping; | ||
| gen_pool_set_algo(atomic_pool, gen_pool_first_fit_order_align, NULL); | ||
|
|
||
| pr_info("DMA: preallocated %zu KiB pool for atomic allocations\n", | ||
| atomic_pool_size / 1024); | ||
| return 0; | ||
|
|
||
| remove_mapping: | ||
| dma_common_free_remap(addr, atomic_pool_size); | ||
| destroy_genpool: | ||
| gen_pool_destroy(atomic_pool); | ||
| atomic_pool = NULL; | ||
| free_page: | ||
| if (!dma_release_from_contiguous(NULL, page, nr_pages)) | ||
| __free_pages(page, pool_size_order); | ||
| out: | ||
| pr_err("DMA: failed to allocate %zu KiB pool for atomic coherent allocation\n", | ||
| atomic_pool_size / 1024); | ||
| return -ENOMEM; | ||
| } | ||
| postcore_initcall(dma_atomic_pool_init); | ||
|
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||
| bool dma_in_atomic_pool(void *start, size_t size) | ||
| { | ||
| if (unlikely(!atomic_pool)) | ||
| return false; | ||
|
|
||
| return gen_pool_has_addr(atomic_pool, (unsigned long)start, size); | ||
| } | ||
|
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||
| void *dma_alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags) | ||
| { | ||
| unsigned long val; | ||
| void *ptr = NULL; | ||
|
|
||
| if (!atomic_pool) { | ||
| WARN(1, "coherent pool not initialised!\n"); | ||
| return NULL; | ||
| } | ||
|
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| val = gen_pool_alloc(atomic_pool, size); | ||
| if (val) { | ||
| phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val); | ||
|
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| *ret_page = pfn_to_page(__phys_to_pfn(phys)); | ||
| ptr = (void *)val; | ||
| memset(ptr, 0, size); | ||
| } | ||
|
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| return ptr; | ||
| } | ||
|
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| bool dma_free_from_pool(void *start, size_t size) | ||
| { | ||
| if (!dma_in_atomic_pool(start, size)) | ||
| return false; | ||
| gen_pool_free(atomic_pool, (unsigned long)start, size); | ||
| return true; | ||
| } |
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