[media] vmalloc_sg: make sure all pages in vmalloc area are really DMA-ready

Patch originally written by Konrad. Rebased on current linux media tree.

Under Xen, vmalloc_32() isn't guaranteed to return pages which are really
under 4G in machine physical addresses (only in virtual pseudo-physical
addresses).  To work around this, implement a vmalloc variant which
allocates each page with dma_alloc_coherent() to guarantee that each
page is suitable for the device in question.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: James Harper <james.harper@ejbdigital.com.au>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

2 files changed, 61 insertions, 4 deletions

diff --git a/drivers/media/v4l2-core/videobuf-dma-sg.c b/drivers/media/v4l2-core/videobuf-dma-sg.c
index 828e7c10bd70..3c8cc023a5a5 100644
--- a/drivers/media/v4l2-core/videobuf-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf-dma-sg.c
@@ -211,13 +211,36 @@ EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
                              int nr_pages)
 {
+        int i;
+
         dprintk(1, "init kernel [%d pages]\n", nr_pages);
 
         dma->direction = direction;
-        dma->vaddr = vmalloc_32(nr_pages << PAGE_SHIFT);
+        dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
+                                   GFP_KERNEL);
+        if (!dma->vaddr_pages)
+                return -ENOMEM;
+
+        dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
+        if (!dma->dma_addr) {
+                kfree(dma->vaddr_pages);
+                return -ENOMEM;
+        }
+        for (i = 0; i < nr_pages; i++) {
+                void *addr;
+
+                addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
+                                          &(dma->dma_addr[i]), GFP_KERNEL);
+                if (addr == NULL)
+                        goto out_free_pages;
+
+                dma->vaddr_pages[i] = virt_to_page(addr);
+        }
+        dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP | VM_IOREMAP,
+                          PAGE_KERNEL);
         if (NULL == dma->vaddr) {
                 dprintk(1, "vmalloc_32(%d pages) failed\n", nr_pages);
-                return -ENOMEM;
+                goto out_free_pages;
         }
 
         dprintk(1, "vmalloc is at addr 0x%08lx, size=%d\n",
@@ -228,6 +251,19 @@ int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
         dma->nr_pages = nr_pages;
 
         return 0;
+out_free_pages:
+        while (i > 0) {
+                void *addr = page_address(dma->vaddr_pages[i]);
+                dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
+                i--;
+        }
+        kfree(dma->dma_addr);
+        dma->dma_addr = NULL;
+        kfree(dma->vaddr_pages);
+        dma->vaddr_pages = NULL;
+
+        return -ENOMEM;
+
 }
 EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
 
@@ -322,8 +358,21 @@ int videobuf_dma_free(struct videobuf_dmabuf *dma)
                 dma->pages = NULL;
         }
 
-        vfree(dma->vaddr);
-        dma->vaddr = NULL;
+        if (dma->dma_addr) {
+                for (i = 0; i < dma->nr_pages; i++) {
+                        void *addr;
+
+                        addr = page_address(dma->vaddr_pages[i]);
+                        dma_free_coherent(dma->dev, PAGE_SIZE, addr,
+                                          dma->dma_addr[i]);
+                }
+                kfree(dma->dma_addr);
+                dma->dma_addr = NULL;
+                kfree(dma->vaddr_pages);
+                dma->vaddr_pages = NULL;
+                vunmap(dma->vaddr);
+                dma->vaddr = NULL;
+        }
 
         if (dma->bus_addr)
                 dma->bus_addr = 0;
@@ -461,6 +510,11 @@ static int __videobuf_iolock(struct videobuf_queue *q,
 
         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 
+        if (!mem->dma.dev)
+                mem->dma.dev = q->dev;
+        else
+                WARN_ON(mem->dma.dev != q->dev);
+
         switch (vb->memory) {
         case V4L2_MEMORY_MMAP:
         case V4L2_MEMORY_USERPTR:
diff --git a/include/media/videobuf-dma-sg.h b/include/media/videobuf-dma-sg.h
index d8fb6012c10d..fb6fd4d8f4ed 100644
--- a/include/media/videobuf-dma-sg.h
+++ b/include/media/videobuf-dma-sg.h
@@ -53,6 +53,9 @@ struct videobuf_dmabuf {
 
         /* for kernel buffers */
         void                *vaddr;
+        struct page         **vaddr_pages;
+        dma_addr_t          *dma_addr;
+        struct device       *dev;
 
         /* for overlay buffers (pci-pci dma) */
         dma_addr_t          bus_addr;