From e860c299ac0d738b44ff91693f11e63080a29698 Mon Sep 17 00:00:00 2001
From: David Rientjes <rientjes@google.com>
Date: Tue, 14 Apr 2020 17:04:52 -0700
Subject: 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>
---
kernel/dma/pool.c | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 123 insertions(+)
create mode 100644 kernel/dma/pool.c
(limited to 'kernel/dma/pool.c')
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
new file mode 100644
index 000000000000..3df5d9d39922
--- /dev/null
+++ b/kernel/dma/pool.c
@@ -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);
+
+ atomic_pool = gen_pool_create(PAGE_SHIFT, -1);
+ if (!atomic_pool)
+ goto free_page;
+
+ 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);
+
+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);
+}
+
+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;
+ }
+
+ val = gen_pool_alloc(atomic_pool, size);
+ if (val) {
+ phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);
+
+ *ret_page = pfn_to_page(__phys_to_pfn(phys));
+ ptr = (void *)val;
+ memset(ptr, 0, size);
+ }
+
+ return ptr;
+}
+
+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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