Messages in this thread Patch in this message | | | From | Jisheng Zhang <> | Subject | [PATCH v2] riscv: mm: still create swiotlb buffer for kmalloc() bouncing if required | Date | Sat, 2 Dec 2023 21:42:24 +0800 |
| |
After commit f51f7a0fc2f4 ("riscv: enable DMA_BOUNCE_UNALIGNED_KMALLOC for !dma_coherent"), for non-coherent platforms with less than 4GB memory, we rely on users to pass "swiotlb=mmnn,force" kernel parameters to enable DMA bouncing for unaligned kmalloc() buffers. Now let's go further: If no bouncing needed for ZONE_DMA, let kernel automatically allocate 1MB swiotlb buffer per 1GB of RAM for kmalloc() bouncing on non-coherent platforms, so that no need to pass "swiotlb=mmnn,force" any more.
The math of "1MB swiotlb buffer per 1GB of RAM for kmalloc() bouncing" is taken from arm64. Users can still force smaller swiotlb buffer by passing "swiotlb=mmnn".
Signed-off-by: Jisheng Zhang <jszhang@kernel.org> ---
since v2: - fix build error if CONFIG_RISCV_DMA_NONCOHERENT=n
arch/riscv/include/asm/cache.h | 2 +- arch/riscv/mm/init.c | 16 +++++++++++++++- 2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/include/asm/cache.h b/arch/riscv/include/asm/cache.h index 2174fe7bac9a..570e9d8acad1 100644 --- a/arch/riscv/include/asm/cache.h +++ b/arch/riscv/include/asm/cache.h @@ -26,8 +26,8 @@ #ifndef __ASSEMBLY__ -#ifdef CONFIG_RISCV_DMA_NONCOHERENT extern int dma_cache_alignment; +#ifdef CONFIG_RISCV_DMA_NONCOHERENT #define dma_get_cache_alignment dma_get_cache_alignment static inline int dma_get_cache_alignment(void) { diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 2e011cbddf3a..cbcb9918f721 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -162,11 +162,25 @@ static void print_vm_layout(void) { } void __init mem_init(void) { + bool swiotlb = max_pfn > PFN_DOWN(dma32_phys_limit); #ifdef CONFIG_FLATMEM BUG_ON(!mem_map); #endif /* CONFIG_FLATMEM */ - swiotlb_init(max_pfn > PFN_DOWN(dma32_phys_limit), SWIOTLB_VERBOSE); + if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb && + dma_cache_alignment != 1) { + /* + * If no bouncing needed for ZONE_DMA, allocate 1MB swiotlb + * buffer per 1GB of RAM for kmalloc() bouncing on + * non-coherent platforms. + */ + unsigned long size = + DIV_ROUND_UP(memblock_phys_mem_size(), 1024); + swiotlb_adjust_size(min(swiotlb_size_or_default(), size)); + swiotlb = true; + } + + swiotlb_init(swiotlb, SWIOTLB_VERBOSE); memblock_free_all(); print_vm_layout(); -- 2.42.0
| |