[PATCH 22/34] dma-mapping: add an arch_dma_supported hook

Christoph Hellwig
2018-01-12T08:42:20Z

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-jcswGhMUV9g@public.gmane.org>
---
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 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