[PATCH V2 2/6] dma-mapping: Add vmap/vunmap_noncontiguous() callback in dma ops

[Tianyu Lan <ltykernel@xxxxxxxxx>]

From: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>

Hyper-V netvsc driver needs to allocate noncontiguous DMA memory and
remap it into unencrypted address space before sharing with host. Add
vmap/vunmap_noncontiguous() callback and handle the remap in the Hyper-V
dma ops callback.

Signed-off-by: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
---
 include/linux/dma-map-ops.h |  3 +++
 kernel/dma/mapping.c        | 18 ++++++++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 0d5b06b3a4a6..f7b9958ca20a 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -27,6 +27,9 @@ struct dma_map_ops {
                        unsigned long attrs);
        void (*free_noncontiguous)(struct device *dev, size_t size,
                        struct sg_table *sgt, enum dma_data_direction dir);
+       void *(*vmap_noncontiguous)(struct device *dev, size_t size,
+                       struct sg_table *sgt);
+       void (*vunmap_noncontiguous)(struct device *dev, void *addr);
        int (*mmap)(struct device *, struct vm_area_struct *,
                        void *, dma_addr_t, size_t, unsigned long attrs);
 
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 9478eccd1c8e..7fd751d866cc 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -674,8 +674,14 @@ void *dma_vmap_noncontiguous(struct device *dev, size_t 
size,
        const struct dma_map_ops *ops = get_dma_ops(dev);
        unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 
-       if (ops && ops->alloc_noncontiguous)
-               return vmap(sgt_handle(sgt)->pages, count, VM_MAP, PAGE_KERNEL);
+       if (ops) {
+               if (ops->vmap_noncontiguous)
+                       return ops->vmap_noncontiguous(dev, size, sgt);
+               else if (ops->alloc_noncontiguous)
+                       return vmap(sgt_handle(sgt)->pages, count, VM_MAP,
+                                   PAGE_KERNEL);
+       }
+
        return page_address(sg_page(sgt->sgl));
 }
 EXPORT_SYMBOL_GPL(dma_vmap_noncontiguous);
@@ -684,8 +690,12 @@ void dma_vunmap_noncontiguous(struct device *dev, void 
*vaddr)
 {
        const struct dma_map_ops *ops = get_dma_ops(dev);
 
-       if (ops && ops->alloc_noncontiguous)
-               vunmap(vaddr);
+       if (ops) {
+               if (ops->vunmap_noncontiguous)
+                       ops->vunmap_noncontiguous(dev, vaddr);
+               else if (ops->alloc_noncontiguous)
+                       vunmap(vaddr);
+       }
 }
 EXPORT_SYMBOL_GPL(dma_vunmap_noncontiguous);
 
-- 
2.25.1