On Sun, Aug 11, 2024 at 10:09:35AM +0300, Baruch Siach wrote: > 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 plain address for DMA zone limit. > > Since 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@xxxxxxx> > Co-developed-by: Baruch Siach <baruch@xxxxxxxxxx> > Signed-off-by: Baruch Siach <baruch@xxxxxxxxxx> > --- > arch/arm64/mm/init.c | 30 +++++++++++++++--------------- > arch/powerpc/mm/mem.c | 5 ++++- > arch/s390/mm/init.c | 2 +- > include/linux/dma-direct.h | 2 +- > kernel/dma/direct.c | 6 +++--- > kernel/dma/pool.c | 4 ++-- > kernel/dma/swiotlb.c | 6 +++--- > 7 files changed, 29 insertions(+), 26 deletions(-) > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 9b5ab6818f7f..c45e2152ca9e 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -115,35 +115,35 @@ static void __init arch_reserve_crashkernel(void) > } > > /* > - * 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 > + * Return the maximum physical address for a zone given its 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; > + zone_limit = PHYS_ADDR_MAX; > + else if (phys_start > zone_limit) > + zone_limit = U32_MAX; > > - return min(zone_mask, memblock_end_of_DRAM() - 1) + 1; > + return min(zone_limit, memblock_end_of_DRAM() - 1) + 1; Why do we need to adjust +-1 now that we're no longer using a mask? > } > > 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 Maybe move this block into a helper function so we can avoid three __maybe_unused variables? Will