On 2020-09-08 17:47, Christoph Hellwig wrote:
The __phys_to_dma vs phys_to_dma distinction isn't exactly obvious.  Try
to improve the situation by renaming __phys_to_dma to
phys_to_dma_unencryped, and not forcing architectures that want to
override phys_to_dma to actually provide __phys_to_dma.

Reviewed-by: Robin Murphy <robin.mur...@arm.com>

Signed-off-by: Christoph Hellwig <h...@lst.de>
---
  arch/arm/include/asm/dma-direct.h      |  2 +-
  arch/mips/bmips/dma.c                  |  2 +-
  arch/mips/cavium-octeon/dma-octeon.c   |  2 +-
  arch/mips/include/asm/dma-direct.h     |  2 +-
  arch/mips/loongson2ef/fuloong-2e/dma.c |  2 +-
  arch/mips/loongson2ef/lemote-2f/dma.c  |  2 +-
  arch/mips/loongson64/dma.c             |  2 +-
  arch/mips/pci/pci-ar2315.c             |  2 +-
  arch/mips/pci/pci-xtalk-bridge.c       |  2 +-
  arch/mips/sgi-ip32/ip32-dma.c          |  2 +-
  arch/powerpc/include/asm/dma-direct.h  |  2 +-
  drivers/iommu/intel/iommu.c            |  2 +-
  include/linux/dma-direct.h             | 28 +++++++++++++++-----------
  kernel/dma/direct.c                    |  8 ++++----
  kernel/dma/swiotlb.c                   |  4 ++--
  15 files changed, 34 insertions(+), 30 deletions(-)

diff --git a/arch/arm/include/asm/dma-direct.h 
b/arch/arm/include/asm/dma-direct.h
index a8cee87a93e8ab..bca0de56753439 100644
--- a/arch/arm/include/asm/dma-direct.h
+++ b/arch/arm/include/asm/dma-direct.h
@@ -2,7 +2,7 @@
  #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;
diff --git a/arch/mips/bmips/dma.c b/arch/mips/bmips/dma.c
index ba2a5d33dfd3fa..49061b870680b9 100644
--- a/arch/mips/bmips/dma.c
+++ b/arch/mips/bmips/dma.c
@@ -40,7 +40,7 @@ static struct bmips_dma_range *bmips_dma_ranges;
#define FLUSH_RAC 0x100 -dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t pa)
+dma_addr_t phys_to_dma(struct device *dev, phys_addr_t pa)
  {
        struct bmips_dma_range *r;
diff --git a/arch/mips/cavium-octeon/dma-octeon.c b/arch/mips/cavium-octeon/dma-octeon.c
index 388b13ba2558c2..232fa1017b1ec9 100644
--- a/arch/mips/cavium-octeon/dma-octeon.c
+++ b/arch/mips/cavium-octeon/dma-octeon.c
@@ -168,7 +168,7 @@ void __init octeon_pci_dma_init(void)
  }
  #endif /* CONFIG_PCI */
-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)
  {
  #ifdef CONFIG_PCI
        if (dev && dev_is_pci(dev))
diff --git a/arch/mips/include/asm/dma-direct.h 
b/arch/mips/include/asm/dma-direct.h
index 8e178651c638c2..9a640118316c9d 100644
--- a/arch/mips/include/asm/dma-direct.h
+++ b/arch/mips/include/asm/dma-direct.h
@@ -2,7 +2,7 @@
  #ifndef _MIPS_DMA_DIRECT_H
  #define _MIPS_DMA_DIRECT_H 1
-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);
  phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr);
#endif /* _MIPS_DMA_DIRECT_H */
diff --git a/arch/mips/loongson2ef/fuloong-2e/dma.c 
b/arch/mips/loongson2ef/fuloong-2e/dma.c
index 83fadeb3fd7d56..cea167d8aba8db 100644
--- a/arch/mips/loongson2ef/fuloong-2e/dma.c
+++ b/arch/mips/loongson2ef/fuloong-2e/dma.c
@@ -1,7 +1,7 @@
  // SPDX-License-Identifier: GPL-2.0
  #include <linux/dma-direct.h>
-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)
  {
        return paddr | 0x80000000;
  }
diff --git a/arch/mips/loongson2ef/lemote-2f/dma.c 
b/arch/mips/loongson2ef/lemote-2f/dma.c
index 302b43a14eee74..3c9e994563578c 100644
--- a/arch/mips/loongson2ef/lemote-2f/dma.c
+++ b/arch/mips/loongson2ef/lemote-2f/dma.c
@@ -1,7 +1,7 @@
  // SPDX-License-Identifier: GPL-2.0
  #include <linux/dma-direct.h>
-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)
  {
        return paddr | 0x80000000;
  }
diff --git a/arch/mips/loongson64/dma.c b/arch/mips/loongson64/dma.c
index b3dc5d0bd2b113..364f2f27c8723f 100644
--- a/arch/mips/loongson64/dma.c
+++ b/arch/mips/loongson64/dma.c
@@ -4,7 +4,7 @@
  #include <linux/swiotlb.h>
  #include <boot_param.h>
-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)
  {
        /* We extract 2bit node id (bit 44~47, only bit 44~45 used now) from
         * Loongson-3's 48bit address space and embed it into 40bit */
diff --git a/arch/mips/pci/pci-ar2315.c b/arch/mips/pci/pci-ar2315.c
index d88395684f487d..cef4a47ab06311 100644
--- a/arch/mips/pci/pci-ar2315.c
+++ b/arch/mips/pci/pci-ar2315.c
@@ -170,7 +170,7 @@ static inline dma_addr_t ar2315_dev_offset(struct device 
*dev)
        return 0;
  }
-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)
  {
        return paddr + ar2315_dev_offset(dev);
  }
diff --git a/arch/mips/pci/pci-xtalk-bridge.c b/arch/mips/pci/pci-xtalk-bridge.c
index f1b37f32b55395..50f7d42cca5a78 100644
--- a/arch/mips/pci/pci-xtalk-bridge.c
+++ b/arch/mips/pci/pci-xtalk-bridge.c
@@ -25,7 +25,7 @@
  /*
   * Common phys<->dma mapping for platforms using pci xtalk bridge
   */
-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 pci_dev *pdev = to_pci_dev(dev);
        struct bridge_controller *bc = BRIDGE_CONTROLLER(pdev->bus);
diff --git a/arch/mips/sgi-ip32/ip32-dma.c b/arch/mips/sgi-ip32/ip32-dma.c
index 160317294d97a9..20c6da9d76bc5e 100644
--- a/arch/mips/sgi-ip32/ip32-dma.c
+++ b/arch/mips/sgi-ip32/ip32-dma.c
@@ -18,7 +18,7 @@
#define RAM_OFFSET_MASK 0x3fffffffUL -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)
  {
        dma_addr_t dma_addr = paddr & RAM_OFFSET_MASK;
diff --git a/arch/powerpc/include/asm/dma-direct.h b/arch/powerpc/include/asm/dma-direct.h
index 95b09313d2a4cf..128304cbee1d87 100644
--- a/arch/powerpc/include/asm/dma-direct.h
+++ b/arch/powerpc/include/asm/dma-direct.h
@@ -2,7 +2,7 @@
  #ifndef ASM_POWERPC_DMA_DIRECT_H
  #define ASM_POWERPC_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)
  {
        return paddr + dev->archdata.dma_offset;
  }
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index f8177c59d229a6..7983c13b9eef7d 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3736,7 +3736,7 @@ bounce_map_single(struct device *dev, phys_addr_t paddr, 
size_t size,
         */
        if (!IS_ALIGNED(paddr | size, VTD_PAGE_SIZE)) {
                tlb_addr = swiotlb_tbl_map_single(dev,
-                               __phys_to_dma(dev, io_tlb_start),
+                               phys_to_dma_unencrypted(dev, io_tlb_start),
                                paddr, size, aligned_size, dir, attrs);
                if (tlb_addr == DMA_MAPPING_ERROR) {
                        goto swiotlb_error;
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index f00e262ab6b154..805010ea5346f9 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -16,14 +16,29 @@ extern unsigned int zone_dma_bits;
#ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
  #include <asm/dma-direct.h>
+#ifndef phys_to_dma_unencrypted
+#define phys_to_dma_unencrypted                phys_to_dma
+#endif
  #else
-static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
+static inline dma_addr_t phys_to_dma_unencrypted(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);
  }
+/*
+ * 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.
+ * phys_to_dma_unencrypted is for use on special unencrypted memory like 
swiotlb
+ * buffers.
+ */
+static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
+{
+       return __sme_set(phys_to_dma_unencrypted(dev, paddr));
+}
+
  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 +
@@ -42,17 +57,6 @@ static inline bool force_dma_unencrypted(struct device *dev)
  }
  #endif /* CONFIG_ARCH_HAS_FORCE_DMA_UNENCRYPTED */
-/*
- * 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
- * version 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 bool dma_capable(struct device *dev, dma_addr_t addr, size_t 
size,
                bool is_ram)
  {
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index bfb479c8a370fa..54db9cfdaecc6d 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -25,7 +25,7 @@ static inline dma_addr_t phys_to_dma_direct(struct device 
*dev,
                phys_addr_t phys)
  {
        if (force_dma_unencrypted(dev))
-               return __phys_to_dma(dev, phys);
+               return phys_to_dma_unencrypted(dev, phys);
        return phys_to_dma(dev, phys);
  }
@@ -438,13 +438,13 @@ int dma_direct_supported(struct device *dev, u64 mask)
                return 1;
/*
-        * This check needs to be against the actual bit mask value, so
-        * use __phys_to_dma() here so that the SME encryption mask isn't
+        * This check needs to be against the actual bit mask value, so use
+        * phys_to_dma_unencrypted() here so that the SME encryption mask isn't
         * part of the check.
         */
        if (IS_ENABLED(CONFIG_ZONE_DMA))
                min_mask = min_t(u64, min_mask, DMA_BIT_MASK(zone_dma_bits));
-       return mask >= __phys_to_dma(dev, min_mask);
+       return mask >= phys_to_dma_unencrypted(dev, min_mask);
  }
size_t dma_direct_max_mapping_size(struct device *dev)
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index c19379fabd200e..4ea72d145cd27d 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -670,13 +670,13 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t 
paddr, size_t size,
                              swiotlb_force);
swiotlb_addr = swiotlb_tbl_map_single(dev,
-                       __phys_to_dma(dev, io_tlb_start),
+                       phys_to_dma_unencrypted(dev, io_tlb_start),
                        paddr, size, size, dir, attrs);
        if (swiotlb_addr == (phys_addr_t)DMA_MAPPING_ERROR)
                return DMA_MAPPING_ERROR;
/* Ensure that the address returned is DMA'ble */
-       dma_addr = __phys_to_dma(dev, swiotlb_addr);
+       dma_addr = phys_to_dma_unencrypted(dev, swiotlb_addr);
        if (unlikely(!dma_capable(dev, dma_addr, size, true))) {
                swiotlb_tbl_unmap_single(dev, swiotlb_addr, size, size, dir,
                        attrs | DMA_ATTR_SKIP_CPU_SYNC);

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