From: Catalin Marinas <catalin.marinas@xxxxxxx> Hardware DMA limit might not be power of 2. When RAM range starts above 0, say 4GB, DMA limit of 30 bits should end at 5GB. A single high bit can not encode this limit. Use direct phys_addr_t limit address for DMA zone limit. Following commits will add explicit base address to DMA zone. --- Catalin, This is taken almost verbatim from your email: https://lore.kernel.org/all/ZZ2HnHJV3gdzu1Aj@xxxxxxx/ Would you provide your sign-off? Thanks, baruch --- arch/arm64/mm/init.c | 32 ++++++++++---------------------- arch/powerpc/mm/mem.c | 9 ++++----- arch/s390/mm/init.c | 2 +- include/linux/dma-direct.h | 2 +- kernel/dma/direct.c | 6 +++--- kernel/dma/pool.c | 2 +- kernel/dma/swiotlb.c | 4 ++-- 7 files changed, 22 insertions(+), 35 deletions(-) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 03efd86dce0a..00508c69ca9e 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -113,36 +113,24 @@ static void __init arch_reserve_crashkernel(void) low_size, high); } -/* - * Return the maximum physical address for a zone accessible by the given bits - * limit. If DRAM starts above 32-bit, expand the zone to the maximum - * available memory, otherwise cap it at 32-bit. - */ -static phys_addr_t __init max_zone_phys(unsigned int zone_bits) +static phys_addr_t __init max_zone_phys(phys_addr_t zone_limit) { - phys_addr_t zone_mask = DMA_BIT_MASK(zone_bits); - phys_addr_t phys_start = memblock_start_of_DRAM(); - - if (phys_start > U32_MAX) - zone_mask = PHYS_ADDR_MAX; - else if (phys_start > zone_mask) - zone_mask = U32_MAX; - - return min(zone_mask, memblock_end_of_DRAM() - 1) + 1; + return min(zone_limit, memblock_end_of_DRAM() - 1) + 1; } static void __init zone_sizes_init(void) { unsigned long max_zone_pfns[MAX_NR_ZONES] = {0}; - unsigned int __maybe_unused acpi_zone_dma_bits; - unsigned int __maybe_unused dt_zone_dma_bits; - phys_addr_t __maybe_unused dma32_phys_limit = max_zone_phys(32); + phys_addr_t __maybe_unused acpi_zone_dma_limit; + phys_addr_t __maybe_unused dt_zone_dma_limit; + phys_addr_t __maybe_unused dma32_phys_limit = + max_zone_phys(DMA_BIT_MASK(32)); #ifdef CONFIG_ZONE_DMA - acpi_zone_dma_bits = fls64(acpi_iort_dma_get_max_cpu_address()); - dt_zone_dma_bits = fls64(of_dma_get_max_cpu_address(NULL)); - zone_dma_bits = min3(32U, dt_zone_dma_bits, acpi_zone_dma_bits); - arm64_dma_phys_limit = max_zone_phys(zone_dma_bits); + acpi_zone_dma_limit = acpi_iort_dma_get_max_cpu_address(); + dt_zone_dma_limit = of_dma_get_max_cpu_address(NULL); + zone_dma_limit = min(dt_zone_dma_limit, acpi_zone_dma_limit); + arm64_dma_phys_limit = max_zone_phys(zone_dma_limit); max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit); #endif #ifdef CONFIG_ZONE_DMA32 diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 3a440004b97d..4d6f575fd354 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -214,7 +214,7 @@ static int __init mark_nonram_nosave(void) * everything else. GFP_DMA32 page allocations automatically fall back to * ZONE_DMA. * - * By using 31-bit unconditionally, we can exploit zone_dma_bits to inform the + * By using 31-bit unconditionally, we can exploit zone_dma_limit to inform the * generic DMA mapping code. 32-bit only devices (if not handled by an IOMMU * anyway) will take a first dip into ZONE_NORMAL and get otherwise served by * ZONE_DMA. @@ -250,13 +250,12 @@ void __init paging_init(void) * powerbooks. */ if (IS_ENABLED(CONFIG_PPC32)) - zone_dma_bits = 30; + zone_dma_limit = DMA_BIT_MASK(30); else - zone_dma_bits = 31; + zone_dma_limit = DMA_BIT_MASK(31); #ifdef CONFIG_ZONE_DMA - max_zone_pfns[ZONE_DMA] = min(max_low_pfn, - 1UL << (zone_dma_bits - PAGE_SHIFT)); + max_zone_pfns[ZONE_DMA] = min(max_low_pfn, zone_dma_limit >> PAGE_SHIFT); #endif max_zone_pfns[ZONE_NORMAL] = max_low_pfn; #ifdef CONFIG_HIGHMEM diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c index f6391442c0c2..5feaa60933b7 100644 --- a/arch/s390/mm/init.c +++ b/arch/s390/mm/init.c @@ -95,7 +95,7 @@ void __init paging_init(void) vmem_map_init(); sparse_init(); - zone_dma_bits = 31; + zone_dma_limit = DMA_BIT_MASK(31); memset(max_zone_pfns, 0, sizeof(max_zone_pfns)); max_zone_pfns[ZONE_DMA] = virt_to_pfn(MAX_DMA_ADDRESS); max_zone_pfns[ZONE_NORMAL] = max_low_pfn; diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h index 3eb3589ff43e..7cf76f1d3239 100644 --- a/include/linux/dma-direct.h +++ b/include/linux/dma-direct.h @@ -12,7 +12,7 @@ #include <linux/mem_encrypt.h> #include <linux/swiotlb.h> -extern unsigned int zone_dma_bits; +extern phys_addr_t zone_dma_limit; /* * Record the mapping of CPU physical to DMA addresses for a given region. diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 4d543b1e9d57..3b2ebcd4f576 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -20,7 +20,7 @@ * it for entirely different regions. In that case the arch code needs to * override the variable below for dma-direct to work properly. */ -unsigned int zone_dma_bits __ro_after_init = 24; +phys_addr_t zone_dma_limit __ro_after_init = DMA_BIT_MASK(24); static inline dma_addr_t phys_to_dma_direct(struct device *dev, phys_addr_t phys) @@ -59,7 +59,7 @@ static gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 *phys_limit) * zones. */ *phys_limit = dma_to_phys(dev, dma_limit); - if (*phys_limit <= DMA_BIT_MASK(zone_dma_bits)) + if (*phys_limit <= zone_dma_limit) return GFP_DMA; if (*phys_limit <= DMA_BIT_MASK(32)) return GFP_DMA32; @@ -584,7 +584,7 @@ int dma_direct_supported(struct device *dev, u64 mask) * part of the check. */ if (IS_ENABLED(CONFIG_ZONE_DMA)) - min_mask = min_t(u64, min_mask, DMA_BIT_MASK(zone_dma_bits)); + min_mask = min_t(u64, min_mask, zone_dma_limit); return mask >= phys_to_dma_unencrypted(dev, min_mask); } diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index d10613eb0f63..410a7b40e496 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c @@ -70,7 +70,7 @@ static bool cma_in_zone(gfp_t gfp) /* CMA can't cross zone boundaries, see cma_activate_area() */ end = cma_get_base(cma) + size - 1; if (IS_ENABLED(CONFIG_ZONE_DMA) && (gfp & GFP_DMA)) - return end <= DMA_BIT_MASK(zone_dma_bits); + return end <= zone_dma_limit; if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32)) return end <= DMA_BIT_MASK(32); return true; diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 86fe172b5958..96d6eee7d215 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -446,7 +446,7 @@ int swiotlb_init_late(size_t size, gfp_t gfp_mask, if (!remap) io_tlb_default_mem.can_grow = true; if (IS_ENABLED(CONFIG_ZONE_DMA) && (gfp_mask & __GFP_DMA)) - io_tlb_default_mem.phys_limit = DMA_BIT_MASK(zone_dma_bits); + io_tlb_default_mem.phys_limit = zone_dma_limit; else if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp_mask & __GFP_DMA32)) io_tlb_default_mem.phys_limit = DMA_BIT_MASK(32); else @@ -625,7 +625,7 @@ static struct page *swiotlb_alloc_tlb(struct device *dev, size_t bytes, } gfp &= ~GFP_ZONEMASK; - if (phys_limit <= DMA_BIT_MASK(zone_dma_bits)) + if (phys_limit <= zone_dma_limit) gfp |= __GFP_DMA; else if (phys_limit <= DMA_BIT_MASK(32)) gfp |= __GFP_DMA32; -- 2.43.0
