xen/arm,arm64: fix xen_dma_ops after 815dd18 "Consolidate get_dma_ops..."

The following commit:

  commit 815dd18788fe0d41899f51b91d0560279cf16b0d
  Author: Bart Van Assche <bart.vanassche@sandisk.com>
  Date:   Fri Jan 20 13:04:04 2017 -0800

      treewide: Consolidate get_dma_ops() implementations

rearranges get_dma_ops in a way that xen_dma_ops are not returned when
running on Xen anymore, dev->dma_ops is returned instead (see
arch/arm/include/asm/dma-mapping.h:get_arch_dma_ops and
include/linux/dma-mapping.h:get_dma_ops).

Fix the problem by storing dev->dma_ops in dev_archdata, and setting
dev->dma_ops to xen_dma_ops. This way, xen_dma_ops is returned naturally
by get_dma_ops. The Xen code can retrieve the original dev->dma_ops from
dev_archdata when needed. It also allows us to remove __generic_dma_ops
from common headers.

Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
Tested-by: Julien Grall <julien.grall@arm.com>
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org>        [4.11+]
CC: linux@armlinux.org.uk
CC: catalin.marinas@arm.com
CC: will.deacon@arm.com
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
CC: Julien Grall <julien.grall@arm.com>

arch/arm/include/asm/device.h

@@ -15,6 +15,9 @@ struct dev_archdata {
 #endif
 #ifdef CONFIG_ARM_DMA_USE_IOMMU
 	struct dma_iommu_mapping	*mapping;
+#endif
+#ifdef CONFIG_XEN
+	const struct dma_map_ops *dev_dma_ops;
 #endif
 	bool dma_coherent;
 };

arch/arm/include/asm/dma-mapping.h

@@ -16,19 +16,9 @@
 extern const struct dma_map_ops arm_dma_ops;
 extern const struct dma_map_ops arm_coherent_dma_ops;
 
-static inline const struct dma_map_ops *__generic_dma_ops(struct device *dev)
-{
-	if (dev && dev->dma_ops)
-		return dev->dma_ops;
-	return &arm_dma_ops;
-}
-
 static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 {
-	if (xen_initial_domain())
-		return xen_dma_ops;
-	else
-		return __generic_dma_ops(NULL);
+	return &arm_dma_ops;
 }
 
 #define HAVE_ARCH_DMA_SUPPORTED 1

arch/arm/mm/dma-mapping.c

@@ -2414,6 +2414,13 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 		dma_ops = arm_get_dma_map_ops(coherent);
 
 	set_dma_ops(dev, dma_ops);
+
+#ifdef CONFIG_XEN
+	if (xen_initial_domain()) {
+		dev->archdata.dev_dma_ops = dev->dma_ops;
+		dev->dma_ops = xen_dma_ops;
+	}
+#endif
 }
 
 void arch_teardown_dma_ops(struct device *dev)

arch/arm64/include/asm/device.h

@@ -19,6 +19,9 @@
 struct dev_archdata {
 #ifdef CONFIG_IOMMU_API
 	void *iommu;			/* private IOMMU data */
+#endif
+#ifdef CONFIG_XEN
+	const struct dma_map_ops *dev_dma_ops;
 #endif
 	bool dma_coherent;
 };

arch/arm64/include/asm/dma-mapping.h

@@ -27,11 +27,8 @@
 #define DMA_ERROR_CODE	(~(dma_addr_t)0)
 extern const struct dma_map_ops dummy_dma_ops;
 
-static inline const struct dma_map_ops *__generic_dma_ops(struct device *dev)
+static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 {
-	if (dev && dev->dma_ops)
-		return dev->dma_ops;
-
 	/*
 	 * We expect no ISA devices, and all other DMA masters are expected to
 	 * have someone call arch_setup_dma_ops at device creation time.
@@ -39,14 +36,6 @@ static inline const struct dma_map_ops *__generic_dma_ops(struct device *dev)
 	return &dummy_dma_ops;
 }
 
-static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
-{
-	if (xen_initial_domain())
-		return xen_dma_ops;
-	else
-		return __generic_dma_ops(NULL);
-}
-
 void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 			const struct iommu_ops *iommu, bool coherent);
 #define arch_setup_dma_ops	arch_setup_dma_ops

arch/arm64/mm/dma-mapping.c

@@ -977,4 +977,11 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 
 	dev->archdata.dma_coherent = coherent;
 	__iommu_setup_dma_ops(dev, dma_base, size, iommu);
+
+#ifdef CONFIG_XEN
+	if (xen_initial_domain()) {
+		dev->archdata.dev_dma_ops = dev->dma_ops;
+		dev->dma_ops = xen_dma_ops;
+	}
+#endif
 }

include/xen/arm/page-coherent.h

@@ -2,8 +2,16 @@
 #define _ASM_ARM_XEN_PAGE_COHERENT_H
 
 #include <asm/page.h>
+#include <asm/dma-mapping.h>
 #include <linux/dma-mapping.h>
 
+static inline const struct dma_map_ops *__generic_dma_ops(struct device *dev)
+{
+	if (dev && dev->archdata.dev_dma_ops)
+		return dev->archdata.dev_dma_ops;
+	return get_arch_dma_ops(NULL);
+}
+
 void __xen_dma_map_page(struct device *hwdev, struct page *page,
 	     dma_addr_t dev_addr, unsigned long offset, size_t size,
 	     enum dma_data_direction dir, unsigned long attrs);