[PATCH] arm: mm: dma-mapping: Fix dma_supported() when dev->dma_pfn_offset is not 0

[Peter Ujfalusi]

We can only use direct mapping when LPAE is enabled if the dma_pfn_offset
is 0, otherwise valid dma_masks will be rejected and the DMA support is
going to be denied for peripherals, or DMA drivers.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
---
 arch/arm/mm/dma-mapping.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 7d042d5c43e3..bf199b1e82bd 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1100,15 +1100,6 @@ int arm_dma_supported(struct device *dev, u64 mask)
 
 static const struct dma_map_ops *arm_get_dma_map_ops(bool coherent)
 {
-	/*
-	 * When CONFIG_ARM_LPAE is set, physical address can extend above
-	 * 32-bits, which then can't be addressed by devices that only support
-	 * 32-bit DMA.
-	 * Use the generic dma-direct / swiotlb ops code in that case, as that
-	 * handles bounce buffering for us.
-	 */
-	if (IS_ENABLED(CONFIG_ARM_LPAE))
-		return NULL;
 	return coherent ? &arm_coherent_dma_ops : &arm_dma_ops;
 }
 
@@ -2309,6 +2300,15 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 
 	if (arm_setup_iommu_dma_ops(dev, dma_base, size, iommu))
 		dma_ops = arm_get_iommu_dma_map_ops(coherent);
+	else if (IS_ENABLED(CONFIG_ARM_LPAE) && !dev->dma_pfn_offset)
+		/*
+		 * When CONFIG_ARM_LPAE is set, physical address can extend
+		 * above * 32-bits, which then can't be addressed by devices
+		 * that only support 32-bit DMA.
+		 * Use the generic dma-direct / swiotlb ops code in that case,
+		 * as that handles bounce buffering for us.
+		 */
+		dma_ops = NULL;
 	else
 		dma_ops = arm_get_dma_map_ops(coherent);
 
-- 
- Péter

> Fixes: 21e07dba9fb11 ("scsi: reduce use of block bounce buffers").
> Reported-by: Roger Quadros <rogerq@xxxxxx>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
>  arch/arm/include/asm/dma-mapping.h |  4 +-
>  arch/arm/mm/Kconfig                |  5 +++
>  arch/arm/mm/dma-mapping.c          | 61 ++++++++++++++++++++++++++++++
>  arch/arm/mm/init.c                 |  5 +++
>  4 files changed, 74 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
> index 03ba90ffc0f8..054119cd7757 100644
> --- a/arch/arm/include/asm/dma-mapping.h
> +++ b/arch/arm/include/asm/dma-mapping.h
> @@ -18,7 +18,9 @@ extern const struct dma_map_ops arm_coherent_dma_ops;
>  
>  static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
>  {
> -	return IS_ENABLED(CONFIG_MMU) ? &arm_dma_ops : NULL;
> +	if (IS_ENABLED(CONFIG_MMU) && !IS_ENABLED(CONFIG_ARM_LPAE))
> +		return &arm_dma_ops;
> +	return NULL;
>  }
>  
>  #ifdef __arch_page_to_dma
> diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
> index b169e580bf82..2dd36183d0e6 100644
> --- a/arch/arm/mm/Kconfig
> +++ b/arch/arm/mm/Kconfig
> @@ -663,6 +663,11 @@ config ARM_LPAE
>  	depends on MMU && CPU_32v7 && !CPU_32v6 && !CPU_32v5 && \
>  		!CPU_32v4 && !CPU_32v3
>  	select PHYS_ADDR_T_64BIT
> +	select SWIOTLB
> +	select ARCH_HAS_DMA_COHERENT_TO_PFN
> +	select ARCH_HAS_DMA_MMAP_PGPROT
> +	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
> +	select ARCH_HAS_SYNC_DMA_FOR_CPU
>  	help
>  	  Say Y if you have an ARMv7 processor supporting the LPAE page
>  	  table format and you would like to access memory beyond the
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index bdf0d236aaee..01a5b96d76a7 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -18,6 +18,7 @@
>  #include <linux/init.h>
>  #include <linux/device.h>
>  #include <linux/dma-mapping.h>
> +#include <linux/dma-noncoherent.h>
>  #include <linux/dma-contiguous.h>
>  #include <linux/highmem.h>
>  #include <linux/memblock.h>
> @@ -1129,6 +1130,19 @@ int arm_dma_supported(struct device *dev, u64 mask)
>  
>  static const struct dma_map_ops *arm_get_dma_map_ops(bool coherent)
>  {
> +	/*
> +	 * When CONFIG_ARM_LPAE is set, physical address can extend above
> +	 * 32-bits, which then can't be addressed by devices that only support
> +	 * 32-bit DMA.
> +	 * Use the generic dma-direct / swiotlb ops code in that case, as that
> +	 * handles bounce buffering for us.
> +	 *
> +	 * Note: this checks CONFIG_ARM_LPAE instead of CONFIG_SWIOTLB as the
> +	 * latter is also selected by the Xen code, but that code for now relies
> +	 * on non-NULL dev_dma_ops.  To be cleaned up later.
> +	 */
> +	if (IS_ENABLED(CONFIG_ARM_LPAE))
> +		return NULL;
>  	return coherent ? &arm_coherent_dma_ops : &arm_dma_ops;
>  }
>  
> @@ -2333,6 +2347,9 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
>  	const struct dma_map_ops *dma_ops;
>  
>  	dev->archdata.dma_coherent = coherent;
> +#ifdef CONFIG_SWIOTLB
> +	dev->dma_coherent = coherent;
> +#endif
>  
>  	/*
>  	 * Don't override the dma_ops if they have already been set. Ideally
> @@ -2367,3 +2384,47 @@ void arch_teardown_dma_ops(struct device *dev)
>  	/* Let arch_setup_dma_ops() start again from scratch upon re-probe */
>  	set_dma_ops(dev, NULL);
>  }
> +
> +#ifdef CONFIG_SWIOTLB
> +void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
> +		size_t size, enum dma_data_direction dir)
> +{
> +	__dma_page_cpu_to_dev(phys_to_page(paddr), paddr & (PAGE_SIZE - 1),
> +			      size, dir);
> +}
> +
> +void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
> +		size_t size, enum dma_data_direction dir)
> +{
> +	__dma_page_dev_to_cpu(phys_to_page(paddr), paddr & (PAGE_SIZE - 1),
> +			      size, dir);
> +}
> +
> +long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
> +		dma_addr_t dma_addr)
> +{
> +	return dma_to_pfn(dev, dma_addr);
> +}
> +
> +pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
> +		unsigned long attrs)
> +{
> +	if (!dev_is_dma_coherent(dev))
> +		return __get_dma_pgprot(attrs, prot);
> +	return prot;
> +}
> +
> +void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
> +		gfp_t gfp, unsigned long attrs)
> +{
> +	return __dma_alloc(dev, size, dma_handle, gfp,
> +			   __get_dma_pgprot(attrs, PAGE_KERNEL), false,
> +			   attrs, __builtin_return_address(0));
> +}
> +
> +void arch_dma_free(struct device *dev, size_t size, void *cpu_addr,
> +		dma_addr_t dma_handle, unsigned long attrs)
> +{
> +	__arm_dma_free(dev, size, cpu_addr, dma_handle, attrs, false);
> +}
> +#endif /* CONFIG_SWIOTLB */
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index be0b42937888..64541be15d43 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -24,6 +24,7 @@
>  #include <linux/dma-contiguous.h>
>  #include <linux/sizes.h>
>  #include <linux/stop_machine.h>
> +#include <linux/swiotlb.h>
>  
>  #include <asm/cp15.h>
>  #include <asm/mach-types.h>
> @@ -456,6 +457,10 @@ void __init mem_init(void)
>  	extern u32 itcm_end;
>  #endif
>  
> +#ifdef CONFIG_ARM_LPAE
> +	swiotlb_init(1);
> +#endif
> +
>  	set_max_mapnr(pfn_to_page(max_pfn) - mem_map);
>  
>  	/* this will put all unused low memory onto the freelists */
> 

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