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Message-ID: <20240812075229.7caf7bab@mordecai.tesarici.cz>
Date: Mon, 12 Aug 2024 07:52:29 +0200
From: Petr Tesarik <ptesarik@...e.com>
To: Baruch Siach <baruch@...s.co.il>
Cc: Christoph Hellwig <hch@....de>, Marek Szyprowski
<m.szyprowski@...sung.com>, Catalin Marinas <catalin.marinas@....com>, Will
Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
iommu@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-s390@...r.kernel.org, Ramon Fried <ramon@...reality.ai>, Elad Nachman
<enachman@...vell.com>, Petr Tesařík <petr@...arici.cz>
Subject: Re: [PATCH v6 RESED 1/2] dma: replace zone_dma_bits by
zone_dma_limit
On Sun, 11 Aug 2024 10:09:35 +0300
Baruch Siach <baruch@...s.co.il> wrote:
> From: Catalin Marinas <catalin.marinas@....com>
>
> 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@....com>
> Co-developed-by: Baruch Siach <baruch@...s.co.il>
> Signed-off-by: Baruch Siach <baruch@...s.co.il>
LGTM.
Reviewed-by: Petr Tesarik <ptesarik@...e.com>
Petr T
> ---
> 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;
> }
>
> 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 d325217ab201..05b7f702b3f7 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));
> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> index ddcd39ef4346..91fc2b91adfc 100644
> --- a/arch/s390/mm/init.c
> +++ b/arch/s390/mm/init.c
> @@ -97,7 +97,7 @@ 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 edbe13d00776..d7e30d4f7503 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 u64 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 4480a3cd92e0..f2ba074a6a54 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;
> +u64 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;
> @@ -580,7 +580,7 @@ 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..7b04f7575796 100644
> --- a/kernel/dma/pool.c
> +++ b/kernel/dma/pool.c
> @@ -70,9 +70,9 @@ 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 end <= max(DMA_BIT_MASK(32), zone_dma_limit);
> return true;
> }
>
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index df68d29740a0..abcf3fa63a56 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -450,9 +450,9 @@ 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);
> + io_tlb_default_mem.phys_limit = max(DMA_BIT_MASK(32), zone_dma_limit);
> else
> io_tlb_default_mem.phys_limit = virt_to_phys(high_memory - 1);
> #endif
> @@ -629,7 +629,7 @@ 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;
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