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Subject: Re: [PATCH 12/14] dma-direct: handle the memory encryption bit in
 common code
To:     Christoph Hellwig <hch@lst.de>, x86@kernel.org
Cc:     Tom Lendacky <thomas.lendacky@amd.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        linux-kernel@vger.kernel.org, Muli Ben-Yehuda <mulix@mulix.org>,
        iommu@lists.linux-foundation.org,
        David Woodhouse <dwmw2@infradead.org>,
        Will Deacon <will.deacon@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>
References: <20180319103826.12853-1-hch@lst.de>
 <20180319103826.12853-13-hch@lst.de>
From:   Robin Murphy <robin.murphy@arm.com>
Message-ID: <dd05dd14-9969-7985-826e-f440c3fc4c08@arm.com>
Date:   Mon, 19 Mar 2018 15:19:04 +0000
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On 19/03/18 10:38, Christoph Hellwig wrote:
> Give the basic phys_to_dma and dma_to_phys helpers a __-prefix and add
> the memory encryption mask to the non-prefixed versions.  Use the
> __-prefixed versions directly instead of clearing the mask again in
> various places.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   arch/arm/include/asm/dma-direct.h                  |  4 ++--

As a heads-up, I've just realised there's now a silent (but 
build-breaking) conflict with the current arm64 queue brewing here, as 
we've unfortunately had to reintroduce ARCH_HAS_PHYS_TO_DMA as a means 
of being safe against an ugly architectural corner case - currently 
commit 1f85b42a691c ("arm64: Revert L1_CACHE_SHIFT back to 6 (64-byte 
cache line size)") in -next.

Robin.

>   arch/mips/cavium-octeon/dma-octeon.c               | 10 ++++-----
>   .../include/asm/mach-cavium-octeon/dma-coherence.h |  4 ++--
>   .../include/asm/mach-loongson64/dma-coherence.h    | 10 ++++-----
>   arch/mips/loongson64/common/dma-swiotlb.c          |  4 ++--
>   arch/powerpc/include/asm/dma-direct.h              |  4 ++--
>   arch/x86/Kconfig                                   |  2 +-
>   arch/x86/include/asm/dma-direct.h                  | 25 ++--------------------
>   arch/x86/mm/mem_encrypt.c                          |  2 +-
>   arch/x86/pci/sta2x11-fixup.c                       |  6 +++---
>   include/linux/dma-direct.h                         | 21 ++++++++++++++++--
>   lib/swiotlb.c                                      | 25 ++++++++--------------
>   12 files changed, 53 insertions(+), 64 deletions(-)
> 
> diff --git a/arch/arm/include/asm/dma-direct.h b/arch/arm/include/asm/dma-direct.h
> index 5b0a8a421894..b67e5fc1fe43 100644
> --- a/arch/arm/include/asm/dma-direct.h
> +++ b/arch/arm/include/asm/dma-direct.h
> @@ -2,13 +2,13 @@
>   #ifndef ASM_ARM_DMA_DIRECT_H
>   #define ASM_ARM_DMA_DIRECT_H 1
>   
> -static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> +static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
>   {
>   	unsigned int offset = paddr & ~PAGE_MASK;
>   	return pfn_to_dma(dev, __phys_to_pfn(paddr)) + offset;
>   }
>   
> -static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr)
> +static inline phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t dev_addr)
>   {
>   	unsigned int offset = dev_addr & ~PAGE_MASK;
>   	return __pfn_to_phys(dma_to_pfn(dev, dev_addr)) + offset;
> diff --git a/arch/mips/cavium-octeon/dma-octeon.c b/arch/mips/cavium-octeon/dma-octeon.c
> index c7bb8a407041..7b335ab21697 100644
> --- a/arch/mips/cavium-octeon/dma-octeon.c
> +++ b/arch/mips/cavium-octeon/dma-octeon.c
> @@ -10,7 +10,7 @@
>    * IP32 changes by Ilya.
>    * Copyright (C) 2010 Cavium Networks, Inc.
>    */
> -#include <linux/dma-mapping.h>
> +#include <linux/dma-direct.h>
>   #include <linux/scatterlist.h>
>   #include <linux/bootmem.h>
>   #include <linux/export.h>
> @@ -182,7 +182,7 @@ struct octeon_dma_map_ops {
>   	phys_addr_t (*dma_to_phys)(struct device *dev, dma_addr_t daddr);
>   };
>   
> -dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> +dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
>   {
>   	struct octeon_dma_map_ops *ops = container_of(get_dma_ops(dev),
>   						      struct octeon_dma_map_ops,
> @@ -190,9 +190,9 @@ dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
>   
>   	return ops->phys_to_dma(dev, paddr);
>   }
> -EXPORT_SYMBOL(phys_to_dma);
> +EXPORT_SYMBOL(__phys_to_dma);
>   
> -phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
> +phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t daddr)
>   {
>   	struct octeon_dma_map_ops *ops = container_of(get_dma_ops(dev),
>   						      struct octeon_dma_map_ops,
> @@ -200,7 +200,7 @@ phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
>   
>   	return ops->dma_to_phys(dev, daddr);
>   }
> -EXPORT_SYMBOL(dma_to_phys);
> +EXPORT_SYMBOL(__dma_to_phys);
>   
>   static struct octeon_dma_map_ops octeon_linear_dma_map_ops = {
>   	.dma_map_ops = {
> diff --git a/arch/mips/include/asm/mach-cavium-octeon/dma-coherence.h b/arch/mips/include/asm/mach-cavium-octeon/dma-coherence.h
> index 138edf6b5b48..6eb1ee548b11 100644
> --- a/arch/mips/include/asm/mach-cavium-octeon/dma-coherence.h
> +++ b/arch/mips/include/asm/mach-cavium-octeon/dma-coherence.h
> @@ -69,8 +69,8 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
>   	return addr + size - 1 <= *dev->dma_mask;
>   }
>   
> -dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr);
> -phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr);
> +dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr);
> +phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t daddr);
>   
>   struct dma_map_ops;
>   extern const struct dma_map_ops *octeon_pci_dma_map_ops;
> diff --git a/arch/mips/include/asm/mach-loongson64/dma-coherence.h b/arch/mips/include/asm/mach-loongson64/dma-coherence.h
> index b1b575f5c6c1..64fc44dec0a8 100644
> --- a/arch/mips/include/asm/mach-loongson64/dma-coherence.h
> +++ b/arch/mips/include/asm/mach-loongson64/dma-coherence.h
> @@ -25,13 +25,13 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
>   	return addr + size - 1 <= *dev->dma_mask;
>   }
>   
> -extern dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr);
> -extern phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr);
> +extern dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr);
> +extern phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t daddr);
>   static inline dma_addr_t plat_map_dma_mem(struct device *dev, void *addr,
>   					  size_t size)
>   {
>   #ifdef CONFIG_CPU_LOONGSON3
> -	return phys_to_dma(dev, virt_to_phys(addr));
> +	return __phys_to_dma(dev, virt_to_phys(addr));
>   #else
>   	return virt_to_phys(addr) | 0x80000000;
>   #endif
> @@ -41,7 +41,7 @@ static inline dma_addr_t plat_map_dma_mem_page(struct device *dev,
>   					       struct page *page)
>   {
>   #ifdef CONFIG_CPU_LOONGSON3
> -	return phys_to_dma(dev, page_to_phys(page));
> +	return __phys_to_dma(dev, page_to_phys(page));
>   #else
>   	return page_to_phys(page) | 0x80000000;
>   #endif
> @@ -51,7 +51,7 @@ static inline unsigned long plat_dma_addr_to_phys(struct device *dev,
>   	dma_addr_t dma_addr)
>   {
>   #if defined(CONFIG_CPU_LOONGSON3) && defined(CONFIG_64BIT)
> -	return dma_to_phys(dev, dma_addr);
> +	return __dma_to_phys(dev, dma_addr);
>   #elif defined(CONFIG_CPU_LOONGSON2F) && defined(CONFIG_64BIT)
>   	return (dma_addr > 0x8fffffff) ? dma_addr : (dma_addr & 0x0fffffff);
>   #else
> diff --git a/arch/mips/loongson64/common/dma-swiotlb.c b/arch/mips/loongson64/common/dma-swiotlb.c
> index 7bbcf89475f3..6a739f8ae110 100644
> --- a/arch/mips/loongson64/common/dma-swiotlb.c
> +++ b/arch/mips/loongson64/common/dma-swiotlb.c
> @@ -63,7 +63,7 @@ static int loongson_dma_supported(struct device *dev, u64 mask)
>   	return swiotlb_dma_supported(dev, mask);
>   }
>   
> -dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> +dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
>   {
>   	long nid;
>   #ifdef CONFIG_PHYS48_TO_HT40
> @@ -75,7 +75,7 @@ dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
>   	return paddr;
>   }
>   
> -phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
> +phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t daddr)
>   {
>   	long nid;
>   #ifdef CONFIG_PHYS48_TO_HT40
> diff --git a/arch/powerpc/include/asm/dma-direct.h b/arch/powerpc/include/asm/dma-direct.h
> index a5b59c765426..7702875aabb7 100644
> --- a/arch/powerpc/include/asm/dma-direct.h
> +++ b/arch/powerpc/include/asm/dma-direct.h
> @@ -17,12 +17,12 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
>   	return addr + size - 1 <= *dev->dma_mask;
>   }
>   
> -static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> +static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
>   {
>   	return paddr + get_dma_offset(dev);
>   }
>   
> -static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
> +static inline phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t daddr)
>   {
>   	return daddr - get_dma_offset(dev);
>   }
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 10f482beda1b..1ca4f0874517 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -54,7 +54,6 @@ config X86
>   	select ARCH_HAS_FORTIFY_SOURCE
>   	select ARCH_HAS_GCOV_PROFILE_ALL
>   	select ARCH_HAS_KCOV			if X86_64
> -	select ARCH_HAS_PHYS_TO_DMA
>   	select ARCH_HAS_MEMBARRIER_SYNC_CORE
>   	select ARCH_HAS_PMEM_API		if X86_64
>   	select ARCH_HAS_REFCOUNT
> @@ -692,6 +691,7 @@ config X86_SUPPORTS_MEMORY_FAILURE
>   config STA2X11
>   	bool "STA2X11 Companion Chip Support"
>   	depends on X86_32_NON_STANDARD && PCI
> +	select ARCH_HAS_PHYS_TO_DMA
>   	select X86_DEV_DMA_OPS
>   	select X86_DMA_REMAP
>   	select SWIOTLB
> diff --git a/arch/x86/include/asm/dma-direct.h b/arch/x86/include/asm/dma-direct.h
> index 1295bc622ebe..1a19251eaac9 100644
> --- a/arch/x86/include/asm/dma-direct.h
> +++ b/arch/x86/include/asm/dma-direct.h
> @@ -2,29 +2,8 @@
>   #ifndef ASM_X86_DMA_DIRECT_H
>   #define ASM_X86_DMA_DIRECT_H 1
>   
> -#include <linux/mem_encrypt.h>
> -
> -#ifdef CONFIG_X86_DMA_REMAP /* Platform code defines bridge-specific code */
>   bool dma_capable(struct device *dev, dma_addr_t addr, size_t size);
> -dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr);
> -phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr);
> -#else
> -static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
> -{
> -	if (!dev->dma_mask)
> -		return 0;
> -
> -	return addr + size - 1 <= *dev->dma_mask;
> -}
> -
> -static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> -{
> -	return __sme_set(paddr);
> -}
> +dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr);
> +phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t daddr);
>   
> -static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
> -{
> -	return __sme_clr(daddr);
> -}
> -#endif /* CONFIG_X86_DMA_REMAP */
>   #endif /* ASM_X86_DMA_DIRECT_H */
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index d3b80d5f9828..1a05bea831a8 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -216,7 +216,7 @@ static void *sev_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
>   		 * Since we will be clearing the encryption bit, check the
>   		 * mask with it already cleared.
>   		 */
> -		addr = __sme_clr(phys_to_dma(dev, page_to_phys(page)));
> +		addr = __phys_to_dma(dev, page_to_phys(page));
>   		if ((addr + size) > dev->coherent_dma_mask) {
>   			__free_pages(page, get_order(size));
>   		} else {
> diff --git a/arch/x86/pci/sta2x11-fixup.c b/arch/x86/pci/sta2x11-fixup.c
> index eac58e03f43c..7a5bafb76d77 100644
> --- a/arch/x86/pci/sta2x11-fixup.c
> +++ b/arch/x86/pci/sta2x11-fixup.c
> @@ -207,11 +207,11 @@ bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
>   }
>   
>   /**
> - * phys_to_dma - Return the DMA AMBA address used for this STA2x11 device
> + * __phys_to_dma - Return the DMA AMBA address used for this STA2x11 device
>    * @dev: device for a PCI device
>    * @paddr: Physical address
>    */
> -dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> +dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
>   {
>   	if (!dev->archdata.is_sta2x11)
>   		return paddr;
> @@ -223,7 +223,7 @@ dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
>    * @dev: device for a PCI device
>    * @daddr: STA2x11 AMBA DMA address
>    */
> -phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
> +phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t daddr)
>   {
>   	if (!dev->archdata.is_sta2x11)
>   		return daddr;
> diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
> index bcdb1a3e4b1f..53ad6a47f513 100644
> --- a/include/linux/dma-direct.h
> +++ b/include/linux/dma-direct.h
> @@ -3,18 +3,19 @@
>   #define _LINUX_DMA_DIRECT_H 1
>   
>   #include <linux/dma-mapping.h>
> +#include <linux/mem_encrypt.h>
>   
>   #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
>   #include <asm/dma-direct.h>
>   #else
> -static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> +static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
>   {
>   	dma_addr_t dev_addr = (dma_addr_t)paddr;
>   
>   	return dev_addr - ((dma_addr_t)dev->dma_pfn_offset << PAGE_SHIFT);
>   }
>   
> -static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr)
> +static inline phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t dev_addr)
>   {
>   	phys_addr_t paddr = (phys_addr_t)dev_addr;
>   
> @@ -30,6 +31,22 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
>   }
>   #endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */
>   
> +/*
> + * If memory encryption is supported, phys_to_dma will set the memory encryption
> + * bit in the DMA address, and dma_to_phys will clear it.  The raw __phys_to_dma
> + * and __dma_to_phys versions should only be used on non-encrypted memory for
> + * special occasions like DMA coherent buffers.
> + */
> +static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> +{
> +	return __sme_set(__phys_to_dma(dev, paddr));
> +}
> +
> +static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
> +{
> +	return __sme_clr(__dma_to_phys(dev, daddr));
> +}
> +
>   #ifdef CONFIG_ARCH_HAS_DMA_MARK_CLEAN
>   void dma_mark_clean(void *addr, size_t size);
>   #else
> diff --git a/lib/swiotlb.c b/lib/swiotlb.c
> index 005d1d87bb2e..8b06b4485e65 100644
> --- a/lib/swiotlb.c
> +++ b/lib/swiotlb.c
> @@ -157,13 +157,6 @@ unsigned long swiotlb_size_or_default(void)
>   	return size ? size : (IO_TLB_DEFAULT_SIZE);
>   }
>   
> -/* For swiotlb, clear memory encryption mask from dma addresses */
> -static dma_addr_t swiotlb_phys_to_dma(struct device *hwdev,
> -				      phys_addr_t address)
> -{
> -	return __sme_clr(phys_to_dma(hwdev, address));
> -}
> -
>   /* Note that this doesn't work with highmem page */
>   static dma_addr_t swiotlb_virt_to_bus(struct device *hwdev,
>   				      volatile void *address)
> @@ -622,7 +615,7 @@ map_single(struct device *hwdev, phys_addr_t phys, size_t size,
>   		return SWIOTLB_MAP_ERROR;
>   	}
>   
> -	start_dma_addr = swiotlb_phys_to_dma(hwdev, io_tlb_start);
> +	start_dma_addr = __phys_to_dma(hwdev, io_tlb_start);
>   	return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size,
>   				      dir, attrs);
>   }
> @@ -726,12 +719,12 @@ swiotlb_alloc_buffer(struct device *dev, size_t size, dma_addr_t *dma_handle,
>   		goto out_warn;
>   
>   	phys_addr = swiotlb_tbl_map_single(dev,
> -			swiotlb_phys_to_dma(dev, io_tlb_start),
> +			__phys_to_dma(dev, io_tlb_start),
>   			0, size, DMA_FROM_DEVICE, 0);
>   	if (phys_addr == SWIOTLB_MAP_ERROR)
>   		goto out_warn;
>   
> -	*dma_handle = swiotlb_phys_to_dma(dev, phys_addr);
> +	*dma_handle = __phys_to_dma(dev, phys_addr);
>   	if (dma_coherent_ok(dev, *dma_handle, size))
>   		goto out_unmap;
>   
> @@ -867,10 +860,10 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
>   	map = map_single(dev, phys, size, dir, attrs);
>   	if (map == SWIOTLB_MAP_ERROR) {
>   		swiotlb_full(dev, size, dir, 1);
> -		return swiotlb_phys_to_dma(dev, io_tlb_overflow_buffer);
> +		return __phys_to_dma(dev, io_tlb_overflow_buffer);
>   	}
>   
> -	dev_addr = swiotlb_phys_to_dma(dev, map);
> +	dev_addr = __phys_to_dma(dev, map);
>   
>   	/* Ensure that the address returned is DMA'ble */
>   	if (dma_capable(dev, dev_addr, size))
> @@ -879,7 +872,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
>   	attrs |= DMA_ATTR_SKIP_CPU_SYNC;
>   	swiotlb_tbl_unmap_single(dev, map, size, dir, attrs);
>   
> -	return swiotlb_phys_to_dma(dev, io_tlb_overflow_buffer);
> +	return __phys_to_dma(dev, io_tlb_overflow_buffer);
>   }
>   
>   /*
> @@ -1009,7 +1002,7 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
>   				sg_dma_len(sgl) = 0;
>   				return 0;
>   			}
> -			sg->dma_address = swiotlb_phys_to_dma(hwdev, map);
> +			sg->dma_address = __phys_to_dma(hwdev, map);
>   		} else
>   			sg->dma_address = dev_addr;
>   		sg_dma_len(sg) = sg->length;
> @@ -1073,7 +1066,7 @@ swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
>   int
>   swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
>   {
> -	return (dma_addr == swiotlb_phys_to_dma(hwdev, io_tlb_overflow_buffer));
> +	return (dma_addr == __phys_to_dma(hwdev, io_tlb_overflow_buffer));
>   }
>   
>   /*
> @@ -1085,7 +1078,7 @@ swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
>   int
>   swiotlb_dma_supported(struct device *hwdev, u64 mask)
>   {
> -	return swiotlb_phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
> +	return __phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
>   }
>   
>   #ifdef CONFIG_DMA_DIRECT_OPS
>