[RFC PATCH v3 2/6] swiotlb: Add restricted DMA pool
Claire Chang
tientzu at chromium.org
Wed Jan 6 14:41:20 AEDT 2021
Add the initialization function to create restricted DMA pools from
matching reserved-memory nodes in the device tree.
Signed-off-by: Claire Chang <tientzu at chromium.org>
---
include/linux/device.h | 4 ++
include/linux/swiotlb.h | 7 +-
kernel/dma/Kconfig | 1 +
kernel/dma/swiotlb.c | 144 ++++++++++++++++++++++++++++++++++------
4 files changed, 131 insertions(+), 25 deletions(-)
diff --git a/include/linux/device.h b/include/linux/device.h
index 89bb8b84173e..ca6f71ec8871 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -413,6 +413,7 @@ struct dev_links_info {
* @dma_pools: Dma pools (if dma'ble device).
* @dma_mem: Internal for coherent mem override.
* @cma_area: Contiguous memory area for dma allocations
+ * @dma_io_tlb_mem: Internal for swiotlb io_tlb_mem override.
* @archdata: For arch-specific additions.
* @of_node: Associated device tree node.
* @fwnode: Associated device node supplied by platform firmware.
@@ -515,6 +516,9 @@ struct device {
#ifdef CONFIG_DMA_CMA
struct cma *cma_area; /* contiguous memory area for dma
allocations */
+#endif
+#ifdef CONFIG_SWIOTLB
+ struct io_tlb_mem *dma_io_tlb_mem;
#endif
/* arch specific additions */
struct dev_archdata archdata;
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index dd8eb57cbb8f..a1bbd7788885 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -76,12 +76,13 @@ extern enum swiotlb_force swiotlb_force;
*
* @start: The start address of the swiotlb memory pool. Used to do a quick
* range check to see if the memory was in fact allocated by this
- * API.
+ * API. For restricted DMA pool, this is device tree adjustable.
* @end: The end address of the swiotlb memory pool. Used to do a quick
* range check to see if the memory was in fact allocated by this
- * API.
+ * API. For restricted DMA pool, this is device tree adjustable.
* @nslabs: The number of IO TLB blocks (in groups of 64) between @start and
- * @end. This is command line adjustable via setup_io_tlb_npages.
+ * @end. For default swiotlb, this is command line adjustable via
+ * setup_io_tlb_npages.
* @used: The number of used IO TLB block.
* @list: The free list describing the number of free entries available
* from each index.
diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index 479fc145acfc..131a0a66781b 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -82,6 +82,7 @@ config ARCH_HAS_FORCE_DMA_UNENCRYPTED
config SWIOTLB
bool
select NEED_DMA_MAP_STATE
+ select OF_EARLY_FLATTREE
#
# Should be selected if we can mmap non-coherent mappings to userspace.
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index e4368159f88a..7fb2ac087d23 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -36,6 +36,11 @@
#include <linux/scatterlist.h>
#include <linux/mem_encrypt.h>
#include <linux/set_memory.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/slab.h>
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
#endif
@@ -319,20 +324,21 @@ static void swiotlb_cleanup(void)
max_segment = 0;
}
-int
-swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
+static int swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
+ size_t size)
{
- struct io_tlb_mem *mem = &io_tlb_default_mem;
- unsigned long i, bytes;
+ unsigned long i;
+ void *vaddr = phys_to_virt(start);
- bytes = nslabs << IO_TLB_SHIFT;
+ size = ALIGN(size, 1 << IO_TLB_SHIFT);
+ mem->nslabs = size >> IO_TLB_SHIFT;
+ mem->nslabs = ALIGN(mem->nslabs, IO_TLB_SEGSIZE);
- mem->nslabs = nslabs;
- mem->start = virt_to_phys(tlb);
- mem->end = mem->start + bytes;
+ mem->start = start;
+ mem->end = mem->start + size;
- set_memory_decrypted((unsigned long)tlb, bytes >> PAGE_SHIFT);
- memset(tlb, 0, bytes);
+ set_memory_decrypted((unsigned long)vaddr, size >> PAGE_SHIFT);
+ memset(vaddr, 0, size);
/*
* Allocate and initialize the free list array. This array is used
@@ -356,13 +362,6 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
mem->orig_addr[i] = INVALID_PHYS_ADDR;
}
mem->index = 0;
- no_iotlb_memory = false;
-
- swiotlb_print_info();
-
- late_alloc = 1;
-
- swiotlb_set_max_segment(mem->nslabs << IO_TLB_SHIFT);
return 0;
@@ -375,6 +374,27 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
return -ENOMEM;
}
+int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
+{
+ struct io_tlb_mem *mem = &io_tlb_default_mem;
+ unsigned long bytes = nslabs << IO_TLB_SHIFT;
+ int ret;
+
+ ret = swiotlb_init_io_tlb_mem(mem, virt_to_phys(tlb), bytes);
+ if (ret)
+ return ret;
+
+ no_iotlb_memory = false;
+
+ swiotlb_print_info();
+
+ late_alloc = 1;
+
+ swiotlb_set_max_segment(bytes);
+
+ return 0;
+}
+
void __init swiotlb_exit(void)
{
struct io_tlb_mem *mem = &io_tlb_default_mem;
@@ -703,16 +723,96 @@ bool is_swiotlb_active(void)
#ifdef CONFIG_DEBUG_FS
-static int __init swiotlb_create_debugfs(void)
+static void swiotlb_create_debugfs(struct io_tlb_mem *mem, const char *name,
+ struct dentry *node)
{
- struct io_tlb_mem *mem = &io_tlb_default_mem;
-
- mem->debugfs = debugfs_create_dir("swiotlb", NULL);
+ mem->debugfs = debugfs_create_dir(name, node);
debugfs_create_ulong("io_tlb_nslabs", 0400, mem->debugfs, &mem->nslabs);
debugfs_create_ulong("io_tlb_used", 0400, mem->debugfs, &mem->used);
+}
+
+static int __init swiotlb_create_default_debugfs(void)
+{
+ swiotlb_create_debugfs(&io_tlb_default_mem, "swiotlb", NULL);
+
return 0;
}
-late_initcall(swiotlb_create_debugfs);
+late_initcall(swiotlb_create_default_debugfs);
#endif
+
+static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
+ struct device *dev)
+{
+ struct io_tlb_mem *mem = rmem->priv;
+ int ret;
+
+ if (dev->dma_io_tlb_mem)
+ return -EBUSY;
+
+ if (!mem) {
+ mem = kzalloc(sizeof(*mem), GFP_KERNEL);
+ if (!mem)
+ return -ENOMEM;
+
+ if (!memremap(rmem->base, rmem->size, MEMREMAP_WB)) {
+ ret = -EINVAL;
+ goto cleanup;
+ }
+
+ ret = swiotlb_init_io_tlb_mem(mem, rmem->base, rmem->size);
+ if (ret)
+ goto cleanup;
+
+ rmem->priv = mem;
+ }
+
+#ifdef CONFIG_DEBUG_FS
+ swiotlb_create_debugfs(mem, dev_name(dev), io_tlb_default_mem.debugfs);
+#endif
+
+ dev->dma_io_tlb_mem = mem;
+
+ return 0;
+
+cleanup:
+ kfree(mem);
+
+ return ret;
+}
+
+static void rmem_swiotlb_device_release(struct reserved_mem *rmem,
+ struct device *dev)
+{
+ if (!dev)
+ return;
+
+#ifdef CONFIG_DEBUG_FS
+ debugfs_remove_recursive(dev->dma_io_tlb_mem->debugfs);
+#endif
+ dev->dma_io_tlb_mem = NULL;
+}
+
+static const struct reserved_mem_ops rmem_swiotlb_ops = {
+ .device_init = rmem_swiotlb_device_init,
+ .device_release = rmem_swiotlb_device_release,
+};
+
+static int __init rmem_swiotlb_setup(struct reserved_mem *rmem)
+{
+ unsigned long node = rmem->fdt_node;
+
+ if (of_get_flat_dt_prop(node, "reusable", NULL) ||
+ of_get_flat_dt_prop(node, "linux,cma-default", NULL) ||
+ of_get_flat_dt_prop(node, "linux,dma-default", NULL) ||
+ of_get_flat_dt_prop(node, "no-map", NULL))
+ return -EINVAL;
+
+ rmem->ops = &rmem_swiotlb_ops;
+ pr_info("Reserved memory: created device swiotlb memory pool at %pa, size %ld MiB\n",
+ &rmem->base, (unsigned long)rmem->size / SZ_1M);
+ return 0;
+}
+
+RESERVEDMEM_OF_DECLARE(dma, "restricted-dma-pool", rmem_swiotlb_setup);
--
2.29.2.729.g45daf8777d-goog
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