[PATCH 23/67] dma-mapping: add an arch_dma_supported hook

[Christoph Hellwig <hch@lst.de>]

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 <hch@lst.de>
---
 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 > 0xffffffff && 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 fd5197af882a..72568bf4fc12 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -583,6 +583,14 @@ 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)))
@@ -595,6 +603,9 @@ 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