[PATCH v9 03/13] xen/arm: if(pfn_valid(pfn)) call native dma_ops

Stefano Stabellini
2014-11-12T11:42:51Z

Remove code duplication in mm32.c by calling the native dma_ops if the
page is a local page (not a foreign page). Use a simple pfn_valid(pfn)
check to figure out if the page is local, exploiting the fact that dom0
is mapped 1:1, therefore pfn_valid always returns false when called on a
foreign mfn.

Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

---

Changes in v9:

- remove BUG_ON from the loop;
- add static inline for xen_dma_unmap_page, xen_dma_sync_single_for_cpu,
xen_dma_sync_single_for_device.
---
arch/arm/include/asm/xen/page-coherent.h | 49 +++++++++++++++++++++++++----
arch/arm/xen/mm32.c | 50 +++++++-----------------------
2 files changed, 54 insertions(+), 45 deletions(-)

diff --git a/arch/arm/include/asm/xen/page-coherent.h b/arch/arm/include/asm/xen/page-coherent.h
index e8275ea..9cfd895 100644
--- a/arch/arm/include/asm/xen/page-coherent.h
+++ b/arch/arm/include/asm/xen/page-coherent.h
@@ -5,6 +5,15 @@
#include <linux/dma-attrs.h>
#include <linux/dma-mapping.h>

+void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
+ size_t size, enum dma_data_direction dir,
+ struct dma_attrs *attrs);
+void __xen_dma_sync_single_for_cpu(struct device *hwdev,
+ dma_addr_t handle, size_t size, enum dma_data_direction dir);
+
+void __xen_dma_sync_single_for_device(struct device *hwdev,
+ dma_addr_t handle, size_t size, enum dma_data_direction dir);
+
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)
@@ -26,14 +35,42 @@ static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
__generic_dma_ops(hwdev)->map_page(hwdev, page, offset, size, dir, attrs);
}

-void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
+static inline void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
size_t size, enum dma_data_direction dir,
- struct dma_attrs *attrs);
+ struct dma_attrs *attrs)
+{
+ unsigned long pfn = PFN_DOWN(handle);
+ /* Dom0 is mapped 1:1, so calling pfn_valid on a foreign mfn will
+ * always return false. If the page is local we can safely call the
+ * native dma_ops function, otherwise we call the xen specific
+ * function. */
+ if (pfn_valid(pfn)) {
+ if (__generic_dma_ops(hwdev)->unmap_page)
+ __generic_dma_ops(hwdev)->unmap_page(hwdev, handle, size, dir, attrs);
+ } else
+ __xen_dma_unmap_page(hwdev, handle, size, dir, attrs);
+}

-void xen_dma_sync_single_for_cpu(struct device *hwdev,
- dma_addr_t handle, size_t size, enum dma_data_direction dir);
+static inline void xen_dma_sync_single_for_cpu(struct device *hwdev,
+ dma_addr_t handle, size_t size, enum dma_data_direction dir)
+{
+ unsigned long pfn = PFN_DOWN(handle);
+ if (pfn_valid(pfn)) {
+ if (__generic_dma_ops(hwdev)->sync_single_for_cpu)
+ __generic_dma_ops(hwdev)->sync_single_for_cpu(hwdev, handle, size, dir);
+ } else
+ __xen_dma_sync_single_for_cpu(hwdev, handle, size, dir);
+}

-void xen_dma_sync_single_for_device(struct device *hwdev,
- dma_addr_t handle, size_t size, enum dma_data_direction dir);
+static inline void xen_dma_sync_single_for_device(struct device *hwdev,
+ dma_addr_t handle, size_t size, enum dma_data_direction dir)
+{
+ unsigned long pfn = PFN_DOWN(handle);
+ if (pfn_valid(pfn)) {
+ if (__generic_dma_ops(hwdev)->sync_single_for_device)
+ __generic_dma_ops(hwdev)->sync_single_for_device(hwdev, handle, size, dir);
+ } else
+ __xen_dma_sync_single_for_device(hwdev, handle, size, dir);
+}

#endif /* _ASM_ARM_XEN_PAGE_COHERENT_H */
diff --git a/arch/arm/xen/mm32.c b/arch/arm/xen/mm32.c
index 6153d61..5bb8391 100644
--- a/arch/arm/xen/mm32.c
+++ b/arch/arm/xen/mm32.c
@@ -4,13 +4,15 @@
#include <linux/highmem.h>

#include <xen/features.h>
-
+enum dma_cache_op {
+ DMA_UNMAP,
+ DMA_MAP,
+};

/* functions called by SWIOTLB */

static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
- size_t size, enum dma_data_direction dir,
- void (*op)(const void *, size_t, int))
+ size_t size, enum dma_data_direction dir, enum dma_cache_op op)
{
unsigned long pfn;
size_t left = size;
@@ -20,34 +22,8 @@ static void dma_cache_maint(dma_addr_t handle, unsigned long offset,

do {
size_t len = left;
- void *vaddr;

- if (!pfn_valid(pfn))
- {
- /* TODO: cache flush */
- } else {
- struct page *page = pfn_to_page(pfn);
-
- if (PageHighMem(page)) {
- if (len + offset > PAGE_SIZE)
- len = PAGE_SIZE - offset;
-
- if (cache_is_vipt_nonaliasing()) {
- vaddr = kmap_atomic(page);
- op(vaddr + offset, len, dir);
- kunmap_atomic(vaddr);
- } else {
- vaddr = kmap_high_get(page);
- if (vaddr) {
- op(vaddr + offset, len, dir);
- kunmap_high(page);
- }
- }
- } else {
- vaddr = page_address(page) + offset;
- op(vaddr, len, dir);
- }
- }
+ /* TODO: cache flush */

offset = 0;
pfn++;
@@ -58,20 +34,16 @@ static void dma_cache_maint(dma_addr_t handle, unsigned long offset,
static void __xen_dma_page_dev_to_cpu(struct device *hwdev, dma_addr_t handle,
size_t size, enum dma_data_direction dir)
{
- /* Cannot use __dma_page_dev_to_cpu because we don't have a
- * struct page for handle */
-
- dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, dmac_unmap_area);
+ dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_UNMAP);
}

static void __xen_dma_page_cpu_to_dev(struct device *hwdev, dma_addr_t handle,
size_t size, enum dma_data_direction dir)
{
-
- dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, dmac_map_area);
+ dma_cache_maint(handle & PAGE_MASK, handle & ~PAGE_MASK, size, dir, DMA_MAP);
}

-void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
+void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
size_t size, enum dma_data_direction dir,
struct dma_attrs *attrs)

@@ -84,7 +56,7 @@ void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
__xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
}

-void xen_dma_sync_single_for_cpu(struct device *hwdev,
+void __xen_dma_sync_single_for_cpu(struct device *hwdev,
dma_addr_t handle, size_t size, enum dma_data_direction dir)
{
if (!__generic_dma_ops(hwdev)->sync_single_for_cpu)
@@ -92,7 +64,7 @@ void xen_dma_sync_single_for_cpu(struct device *hwdev,
__xen_dma_page_dev_to_cpu(hwdev, handle, size, dir);
}

-void xen_dma_sync_single_for_device(struct device *hwdev,
+void __xen_dma_sync_single_for_device(struct device *hwdev,
dma_addr_t handle, size_t size, enum dma_data_direction dir)
{
if (!__generic_dma_ops(hwdev)->sync_single_for_device)
--
1.7.10.4