From 8f5c9037a55b22e847f636f9a39fa98fe67923d1 Mon Sep 17 00:00:00 2001 From: Masayoshi Mizuma Date: Fri, 14 Jun 2019 09:11:41 -0400 Subject: [PATCH] arm64/mm: Correct the cache line size warning with non coherent device If the cache line size is greater than ARCH_DMA_MINALIGN (128), the warning shows and it's tainted as TAINT_CPU_OUT_OF_SPEC. However, it's not good because as discussed in the thread [1], the cpu cache line size will be problem only on non-coherent devices. Since the coherent flag is already introduced to struct device, show the warning only if the device is non-coherent device and ARCH_DMA_MINALIGN is smaller than the cpu cache size. [1] https://lore.kernel.org/linux-arm-kernel/20180514145703.celnlobzn3uh5tc2@localhost/ Signed-off-by: Masayoshi Mizuma Reviewed-by: Hidetoshi Seto Tested-by: Zhang Lei [catalin.marinas@arm.com: removed 'if' block for WARN_TAINT] Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/cache.h | 7 +++++++ arch/arm64/kernel/cacheinfo.c | 4 +--- arch/arm64/mm/dma-mapping.c | 12 ++++++++---- 3 files changed, 16 insertions(+), 7 deletions(-) diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h index 758af6340314..d24b7c1ecd9b 100644 --- a/arch/arm64/include/asm/cache.h +++ b/arch/arm64/include/asm/cache.h @@ -91,6 +91,13 @@ static inline u32 cache_type_cwg(void) #define __read_mostly __attribute__((__section__(".data..read_mostly"))) +static inline int cache_line_size_of_cpu(void) +{ + u32 cwg = cache_type_cwg(); + + return cwg ? 4 << cwg : ARCH_DMA_MINALIGN; +} + int cache_line_size(void); /* diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c index 0c0cd4d26b87..969fcc3be556 100644 --- a/arch/arm64/kernel/cacheinfo.c +++ b/arch/arm64/kernel/cacheinfo.c @@ -30,12 +30,10 @@ int cache_line_size(void) { - u32 cwg = cache_type_cwg(); - if (coherency_max_size != 0) return coherency_max_size; - return cwg ? 4 << cwg : ARCH_DMA_MINALIGN; + return cache_line_size_of_cpu(); } EXPORT_SYMBOL_GPL(cache_line_size); diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index 674860e3e478..ff410195dc1c 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -91,10 +91,6 @@ static int __swiotlb_mmap_pfn(struct vm_area_struct *vma, static int __init arm64_dma_init(void) { - WARN_TAINT(ARCH_DMA_MINALIGN < cache_line_size(), - TAINT_CPU_OUT_OF_SPEC, - "ARCH_DMA_MINALIGN smaller than CTR_EL0.CWG (%d < %d)", - ARCH_DMA_MINALIGN, cache_line_size()); return dma_atomic_pool_init(GFP_DMA32, __pgprot(PROT_NORMAL_NC)); } arch_initcall(arm64_dma_init); @@ -472,6 +468,14 @@ static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, const struct iommu_ops *iommu, bool coherent) { + int cls = cache_line_size_of_cpu(); + + WARN_TAINT(!coherent && cls > ARCH_DMA_MINALIGN, + TAINT_CPU_OUT_OF_SPEC, + "%s %s: ARCH_DMA_MINALIGN smaller than CTR_EL0.CWG (%d < %d)", + dev_driver_string(dev), dev_name(dev), + ARCH_DMA_MINALIGN, cls); + dev->dma_coherent = coherent; __iommu_setup_dma_ops(dev, dma_base, size, iommu);