Re: [PATCH 21/33] dma-mapping: add an arch_dma_supported hook

[Konrad Rzeszutek Wilk]

On Wed, Jan 10, 2018 at 09:00:15AM +0100, Christoph Hellwig wrote:
> To implement the x86 forbid_dac and iommu_sac_force we want an arch hook
> so that it can apply the global options across all dma_map_ops
> implementations.
> 
> Signed-off-by: Christoph Hellwig 

Reviewed-by: Konrad Rzeszutek Wilk 
> ---
>  arch/x86/include/asm/dma-mapping.h |  3 +++
>  arch/x86/kernel/pci-dma.c  | 19 ---
>  include/linux/dma-mapping.h| 11 +++
>  3 files changed, 26 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/include/asm/dma-mapping.h 
> b/arch/x86/include/asm/dma-mapping.h
> index dfdc9357a349..6277c83c0eb1 100644
> --- a/arch/x86/include/asm/dma-mapping.h
> +++ b/arch/x86/include/asm/dma-mapping.h
> @@ -30,6 +30,9 @@ static inline const struct dma_map_ops 
> *get_arch_dma_ops(struct bus_type *bus)
>   return dma_ops;
>  }
>  
> +int arch_dma_supported(struct device *dev, u64 mask);
> +#define arch_dma_supported arch_dma_supported
> +
>  bool arch_dma_alloc_attrs(struct device **dev, gfp_t *gfp);
>  #define arch_dma_alloc_attrs arch_dma_alloc_attrs
>  
> diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
> index 61a8f1cb3829..df7ab02f959f 100644
> --- a/arch/x86/kernel/pci-dma.c
> +++ b/arch/x86/kernel/pci-dma.c
> @@ -215,7 +215,7 @@ static __init int iommu_setup(char *p)
>  }
>  early_param("iommu", iommu_setup);
>  
> -int x86_dma_supported(struct device *dev, u64 mask)
> +int arch_dma_supported(struct device *dev, u64 mask)
>  {
>  #ifdef CONFIG_PCI
>   if (mask > 0x && forbid_dac > 0) {
> @@ -224,12 +224,6 @@ int x86_dma_supported(struct device *dev, u64 mask)
>   }
>  #endif
>  
> - /* Copied from i386. Doesn't make much sense, because it will
> -only work for pci_alloc_coherent.
> -The caller just has to use GFP_DMA in this case. */
> - if (mask < DMA_BIT_MASK(24))
> - return 0;
> -
>   /* Tell the device to use SAC when IOMMU force is on.  This
>  allows the driver to use cheaper accesses in some cases.
>  
> @@ -249,6 +243,17 @@ int x86_dma_supported(struct device *dev, u64 mask)
>  
>   return 1;
>  }
> +EXPORT_SYMBOL(arch_dma_supported);
> +
> +int x86_dma_supported(struct device *dev, u64 mask)
> +{
> + /* Copied from i386. Doesn't make much sense, because it will
> +only work for pci_alloc_coherent.
> +The caller just has to use GFP_DMA in this case. */
> + if (mask < DMA_BIT_MASK(24))
> + return 0;
> + return 1;
> +}
>  
>  static int __init pci_iommu_init(void)
>  {
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index 88bcb1a8211d..d67742dad904 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -576,6 +576,14 @@ static inline int dma_mapping_error(struct device *dev, 
> dma_addr_t dma_addr)
>   return 0;
>  }
>  
> +/*
> + * This is a hack for the legacy x86 forbid_dac and iommu_sac_force. Please
> + * don't use this is new code.
> + */
> +#ifndef arch_dma_supported
> +#define arch_dma_supported(dev, mask)(1)
> +#endif
> +
>  static inline void dma_check_mask(struct device *dev, u64 mask)
>  {
>   if (sme_active() && (mask < (((u64)sme_get_me_mask() << 1) - 1)))
> @@ -588,6 +596,9 @@ static inline int dma_supported(struct device *dev, u64 
> mask)
>  
>   if (!ops)
>   return 0;
> + if (!arch_dma_supported(dev, mask))
> + return 0;
> +
>   if (!ops->dma_supported)
>   return 1;
>   return ops->dma_supported(dev, mask);
> -- 
> 2.14.2
> 

[PATCH 21/33] dma-mapping: add an arch_dma_supported hook

[Christoph Hellwig]

To implement the x86 forbid_dac and iommu_sac_force we want an arch hook
so that it can apply the global options across all dma_map_ops
implementations.

Signed-off-by: Christoph Hellwig 
---
 arch/x86/include/asm/dma-mapping.h |  3 +++
 arch/x86/kernel/pci-dma.c  | 19 ---
 include/linux/dma-mapping.h| 11 +++
 3 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/dma-mapping.h 
b/arch/x86/include/asm/dma-mapping.h
index dfdc9357a349..6277c83c0eb1 100644
--- a/arch/x86/include/asm/dma-mapping.h
+++ b/arch/x86/include/asm/dma-mapping.h
@@ -30,6 +30,9 @@ static inline const struct dma_map_ops 
*get_arch_dma_ops(struct bus_type *bus)
return dma_ops;
 }
 
+int arch_dma_supported(struct device *dev, u64 mask);
+#define arch_dma_supported arch_dma_supported
+
 bool arch_dma_alloc_attrs(struct device **dev, gfp_t *gfp);
 #define arch_dma_alloc_attrs arch_dma_alloc_attrs
 
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 61a8f1cb3829..df7ab02f959f 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -215,7 +215,7 @@ static __init int iommu_setup(char *p)
 }
 early_param("iommu", iommu_setup);
 
-int x86_dma_supported(struct device *dev, u64 mask)
+int arch_dma_supported(struct device *dev, u64 mask)
 {
 #ifdef CONFIG_PCI
if (mask > 0x && forbid_dac > 0) {
@@ -224,12 +224,6 @@ int x86_dma_supported(struct device *dev, u64 mask)
}
 #endif
 
-   /* Copied from i386. Doesn't make much sense, because it will
-  only work for pci_alloc_coherent.
-  The caller just has to use GFP_DMA in this case. */
-   if (mask < DMA_BIT_MASK(24))
-   return 0;
-
/* Tell the device to use SAC when IOMMU force is on.  This
   allows the driver to use cheaper accesses in some cases.
 
@@ -249,6 +243,17 @@ int x86_dma_supported(struct device *dev, u64 mask)
 
return 1;
 }
+EXPORT_SYMBOL(arch_dma_supported);
+
+int x86_dma_supported(struct device *dev, u64 mask)
+{
+   /* Copied from i386. Doesn't make much sense, because it will
+  only work for pci_alloc_coherent.
+  The caller just has to use GFP_DMA in this case. */
+   if (mask < DMA_BIT_MASK(24))
+   return 0;
+   return 1;
+}
 
 static int __init pci_iommu_init(void)
 {
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 88bcb1a8211d..d67742dad904 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -576,6 +576,14 @@ static inline int dma_mapping_error(struct device *dev, 
dma_addr_t dma_addr)
return 0;
 }
 
+/*
+ * This is a hack for the legacy x86 forbid_dac and iommu_sac_force. Please
+ * don't use this is new code.
+ */
+#ifndef arch_dma_supported
+#define arch_dma_supported(dev, mask)  (1)
+#endif
+
 static inline void dma_check_mask(struct device *dev, u64 mask)
 {
if (sme_active() && (mask < (((u64)sme_get_me_mask() << 1) - 1)))
@@ -588,6 +596,9 @@ static inline int dma_supported(struct device *dev, u64 
mask)
 
if (!ops)
return 0;
+   if (!arch_dma_supported(dev, mask))
+   return 0;
+
if (!ops->dma_supported)
return 1;
return ops->dma_supported(dev, mask);
-- 
2.14.2