From ba0fb44aed47693cc2482427f63ba6cd19051327 Mon Sep 17 00:00:00 2001 From: Catalin Marinas <catalin.marinas@arm.com> Date: Sun, 11 Aug 2024 10:09:35 +0300 Subject: dma-mapping: replace zone_dma_bits by zone_dma_limit The 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 a plain address for the DMA zone limit instead. Since the DMA zone can now potentially span beyond 4GB physical limit of DMA32, make sure to use DMA zone for GFP_DMA32 allocations in that case. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Co-developed-by: Baruch Siach <baruch@tkos.co.il> Signed-off-by: Baruch Siach <baruch@tkos.co.il> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Petr Tesarik <ptesarik@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> --- arch/powerpc/mm/mem.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'arch/powerpc/mm') diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index da21cb018984..7e217aa4a274 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -216,7 +216,7 @@ 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. @@ -230,6 +230,7 @@ void __init paging_init(void) { unsigned long long total_ram = memblock_phys_mem_size(); phys_addr_t top_of_ram = memblock_end_of_DRAM(); + int zone_dma_bits; #ifdef CONFIG_HIGHMEM unsigned long v = __fix_to_virt(FIX_KMAP_END); @@ -256,6 +257,8 @@ void __init paging_init(void) else zone_dma_bits = 31; + zone_dma_limit = DMA_BIT_MASK(zone_dma_bits); + #ifdef CONFIG_ZONE_DMA max_zone_pfns[ZONE_DMA] = min(max_low_pfn, 1UL << (zone_dma_bits - PAGE_SHIFT)); -- cgit v1.2.3