kybaaz/linux-xiaomi-chiron
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

dma-mapping: remove CONFIG_DMA_REMAP

Browse source 
CONFIG_DMA_REMAP is used to build a few helpers around the core
vmalloc code, and to use them in case there is a highmem page in
dma-direct, and to make dma coherent allocations be able to use
non-contiguous pages allocations for DMA allocations in the dma-iommu
layer.

Right now it needs to be explicitly selected by architectures, and
is only done so by architectures that require remapping to deal
with devices that are not DMA coherent.  Make it unconditional for
builds with CONFIG_MMU as it is very little extra code, but makes
it much more likely that large DMA allocations succeed on x86.

This fixes hot plugging a NVMe thunderbolt SSD for me, which tries
to allocate a 1MB buffer that is otherwise hard to obtain due to
memory fragmentation on a heavily used laptop.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
This commit is contained in:
Christoph Hellwig 2022-02-26 16:40:21 +01:00
parent fba09099c6
commit f5ff79fddf
6 changed files with 16 additions and 29 deletions
Download patch file Download diff file Expand all files Collapse all files

7
kernel/dma/Kconfig
View file

@ -110,15 +110,10 @@ config DMA_GLOBAL_POOL
select DMA_DECLARE_COHERENT
bool
config DMA_REMAP
bool
depends on MMU
select DMA_NONCOHERENT_MMAP
config DMA_DIRECT_REMAP
bool
select DMA_REMAP
select DMA_COHERENT_POOL
select DMA_NONCOHERENT_MMAP
config DMA_CMA
bool "DMA Contiguous Memory Allocator"

2
kernel/dma/Makefile
View file

@ -8,5 +8,5 @@ obj-$(CONFIG_DMA_DECLARE_COHERENT) += coherent.o
obj-$(CONFIG_DMA_API_DEBUG) += debug.o
obj-$(CONFIG_SWIOTLB) += swiotlb.o
obj-$(CONFIG_DMA_COHERENT_POOL) += pool.o
obj-$(CONFIG_DMA_REMAP) += remap.o
obj-$(CONFIG_MMU) += remap.o
obj-$(CONFIG_DMA_MAP_BENCHMARK) += map_benchmark.o

18
kernel/dma/direct.c
View file

@ -265,17 +265,13 @@ void *dma_direct_alloc(struct device *dev, size_t size,
page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO);
if (!page)
return NULL;
/*
* dma_alloc_contiguous can return highmem pages depending on a
* combination the cma= arguments and per-arch setup. These need to be
* remapped to return a kernel virtual address.
*/
if (PageHighMem(page)) {
/*
* Depending on the cma= arguments and per-arch setup,
* dma_alloc_contiguous could return highmem pages.
* Without remapping there is no way to return them here, so
* log an error and fail.
*/
if (!IS_ENABLED(CONFIG_DMA_REMAP)) {
dev_info(dev, "Rejecting highmem page from CMA.\n");
goto out_free_pages;
}
remap = true;
set_uncached = false;
}
@ -349,7 +345,7 @@ void dma_direct_free(struct device *dev, size_t size,
dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size)))
return;
if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) {
if (is_vmalloc_addr(cpu_addr)) {
vunmap(cpu_addr);
} else {
if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED))