[Xen-devel] [PATCH v6 10/19] xen: introduce xen_alloc/free_coherent_pages

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

xen_swiotlb_alloc_coherent needs to allocate a coherent buffer for cpu
and devices. On native x86 and ARMv8 is sufficient to call
__get_free_pages in order to get a coherent buffer, while on ARM we need
to call the native dma_ops->alloc implementation.

When arm64 stops using the swiotlb by default and starts having multiple
dma_ops implementations, we'll use __get_dma_ops there too.

Introduce xen_alloc_coherent_pages to abstract the arch specific buffer
allocation.

Similarly introduce xen_free_coherent_pages to free a coherent buffer:
on x86 and ARM64 is simply a call to free_pages while on ARM is
arm_dma_ops.free.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>


Changes in v6:
- call __get_dma_ops to get the native dma_ops pointer on arm.
---
 arch/arm/include/asm/xen/page-coherent.h   |   22 ++++++++++++++++++++++
 arch/arm64/include/asm/xen/page-coherent.h |   24 ++++++++++++++++++++++++
 arch/ia64/include/asm/xen/page-coherent.h  |   24 ++++++++++++++++++++++++
 arch/x86/include/asm/xen/page-coherent.h   |   24 ++++++++++++++++++++++++
 4 files changed, 94 insertions(+), 0 deletions(-)
 create mode 100644 arch/arm/include/asm/xen/page-coherent.h
 create mode 100644 arch/arm64/include/asm/xen/page-coherent.h
 create mode 100644 arch/ia64/include/asm/xen/page-coherent.h
 create mode 100644 arch/x86/include/asm/xen/page-coherent.h

diff --git a/arch/arm/include/asm/xen/page-coherent.h 
b/arch/arm/include/asm/xen/page-coherent.h
new file mode 100644
index 0000000..92b7a8a
--- /dev/null
+++ b/arch/arm/include/asm/xen/page-coherent.h
@@ -0,0 +1,22 @@
+#ifndef _ASM_ARM_XEN_PAGE_COHERENT_H
+#define _ASM_ARM_XEN_PAGE_COHERENT_H
+
+#include <asm/page.h>
+#include <linux/dma-attrs.h>
+#include <linux/dma-mapping.h>
+
+static inline void *xen_alloc_coherent_pages(struct device *hwdev, size_t size,
+               dma_addr_t *dma_handle, gfp_t flags,
+               struct dma_attrs *attrs)
+{
+       return __get_dma_ops(hwdev)->alloc(hwdev, size, dma_handle, flags, 
attrs);
+}
+
+static inline void xen_free_coherent_pages(struct device *hwdev, size_t size,
+               void *cpu_addr, dma_addr_t dma_handle,
+               struct dma_attrs *attrs)
+{
+       __get_dma_ops(hwdev)->free(hwdev, size, cpu_addr, dma_handle, attrs);
+}
+
+#endif /* _ASM_ARM_XEN_PAGE_COHERENT_H */
diff --git a/arch/arm64/include/asm/xen/page-coherent.h 
b/arch/arm64/include/asm/xen/page-coherent.h
new file mode 100644
index 0000000..0d6ad25
--- /dev/null
+++ b/arch/arm64/include/asm/xen/page-coherent.h
@@ -0,0 +1,24 @@
+#ifndef _ASM_ARM64_XEN_PAGE_COHERENT_H
+#define _ASM_ARM64_XEN_PAGE_COHERENT_H
+
+#include <asm/page.h>
+#include <linux/dma-attrs.h>
+#include <linux/dma-mapping.h>
+
+static inline void *xen_alloc_coherent_pages(struct device *hwdev, size_t size,
+               dma_addr_t *dma_handle, gfp_t flags,
+               struct dma_attrs *attrs)
+{
+       void *vstart = (void*)__get_free_pages(flags, get_order(size));
+       *dma_handle = virt_to_phys(vstart);
+       return vstart;
+}
+
+static inline void xen_free_coherent_pages(struct device *hwdev, size_t size,
+               void *cpu_addr, dma_addr_t dma_handle,
+               struct dma_attrs *attrs)
+{
+       free_pages((unsigned long) cpu_addr, get_order(size));
+}
+
+#endif /* _ASM_ARM64_XEN_PAGE_COHERENT_H */
diff --git a/arch/ia64/include/asm/xen/page-coherent.h 
b/arch/ia64/include/asm/xen/page-coherent.h
new file mode 100644
index 0000000..37b929c
--- /dev/null
+++ b/arch/ia64/include/asm/xen/page-coherent.h
@@ -0,0 +1,24 @@
+#ifndef _ASM_IA64_XEN_PAGE_COHERENT_H
+#define _ASM_IA64_XEN_PAGE_COHERENT_H
+
+#include <asm/page.h>
+#include <linux/dma-attrs.h>
+#include <linux/dma-mapping.h>
+
+static inline void *xen_alloc_coherent_pages(struct device *hwdev, size_t size,
+               dma_addr_t *dma_handle, gfp_t flags,
+               struct dma_attrs *attrs)
+{
+       void *vstart = (void*)__get_free_pages(flags, get_order(size));
+       *dma_handle = virt_to_phys(vstart);
+       return vstart;
+}
+
+static inline void xen_free_coherent_pages(struct device *hwdev, size_t size,
+               void *cpu_addr, dma_addr_t dma_handle,
+               struct dma_attrs *attrs)
+{
+       free_pages((unsigned long) cpu_addr, get_order(size));
+}
+
+#endif /* _ASM_IA64_XEN_PAGE_COHERENT_H */
diff --git a/arch/x86/include/asm/xen/page-coherent.h 
b/arch/x86/include/asm/xen/page-coherent.h
new file mode 100644
index 0000000..31de2e0
--- /dev/null
+++ b/arch/x86/include/asm/xen/page-coherent.h
@@ -0,0 +1,24 @@
+#ifndef _ASM_X86_XEN_PAGE_COHERENT_H
+#define _ASM_X86_XEN_PAGE_COHERENT_H
+
+#include <asm/page.h>
+#include <linux/dma-attrs.h>
+#include <linux/dma-mapping.h>
+
+static inline void *xen_alloc_coherent_pages(struct device *hwdev, size_t size,
+               dma_addr_t *dma_handle, gfp_t flags,
+               struct dma_attrs *attrs)
+{
+       void *vstart = (void*)__get_free_pages(flags, get_order(size));
+       *dma_handle = virt_to_phys(vstart);
+       return vstart;
+}
+
+static inline void xen_free_coherent_pages(struct device *hwdev, size_t size,
+               void *cpu_addr, dma_addr_t dma_handle,
+               struct dma_attrs *attrs)
+{
+       free_pages((unsigned long) cpu_addr, get_order(size));
+}
+
+#endif /* _ASM_X86_XEN_PAGE_COHERENT_H */
-- 
1.7.2.5


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