On Thu, Jun 24, 2021 at 6:59 PM Claire Chang tientzu@chromium.org wrote:
Add the initialization function to create restricted DMA pools from matching reserved-memory nodes.
Regardless of swiotlb setting, the restricted DMA pool is preferred if available.
The restricted DMA pools provide a basic level of protection against the DMA overwriting buffer contents at unexpected times. However, to protect against general data leakage and system memory corruption, the system needs to provide a way to lock down the memory access, e.g., MPU.
+static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
struct device *dev)+{
struct io_tlb_mem *mem = rmem->priv;unsigned long nslabs = rmem->size >> IO_TLB_SHIFT;/** Since multiple devices can share the same pool, the private data,* io_tlb_mem struct, will be initialized by the first device attached* to it.*/
if (!mem) {
Can it be rather
if (mem) goto out_assign;
or so?
mem = kzalloc(struct_size(mem, slots, nslabs), GFP_KERNEL);if (!mem)return -ENOMEM;set_memory_decrypted((unsigned long)phys_to_virt(rmem->base),rmem->size >> PAGE_SHIFT);
Below you are using a macro from pfn.h, but not here, I think it's PFN_DOWN().
swiotlb_init_io_tlb_mem(mem, rmem->base, nslabs, false);mem->force_bounce = true;mem->for_alloc = true;rmem->priv = mem;if (IS_ENABLED(CONFIG_DEBUG_FS)) {mem->debugfs =debugfs_create_dir(rmem->name, debugfs_dir);swiotlb_create_debugfs_files(mem);}}dev->dma_io_tlb_mem = mem;return 0;+}
+static void rmem_swiotlb_device_release(struct reserved_mem *rmem,
struct device *dev)+{
dev->dma_io_tlb_mem = io_tlb_default_mem;+}
+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;if (PageHighMem(pfn_to_page(PHYS_PFN(rmem->base)))) {pr_err("Restricted DMA pool must be accessible within the linear mapping.");return -EINVAL;}rmem->ops = &rmem_swiotlb_ops;pr_info("Reserved memory: created restricted DMA pool at %pa, size %ld MiB\n",&rmem->base, (unsigned long)rmem->size / SZ_1M);
Oh là là, besides explicit casting that I believe can be avoided, %ld != unsigned long. Can you check the printk-formats.rst document?
return 0;+}
+RESERVEDMEM_OF_DECLARE(dma, "restricted-dma-pool", rmem_swiotlb_setup); #endif /* CONFIG_DMA_RESTRICTED_POOL */