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;