mlx4_core: For 64-bit systems, vmap() kernel queue buffers

Since kernel virtual memory is not a problem on 64-bit systems, there
is no reason to use our own 2-layer page mapping scheme for large
kernel queue buffers on such systems.  Instead, map the page list to a
single virtually contiguous buffer with vmap(), so that can we access
buffer memory via direct indexing.

Signed-off-by: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/net/mlx4/alloc.c b/drivers/net/mlx4/alloc.c
index b226e01..2da2c2e 100644 (file)
--- a/drivers/net/mlx4/alloc.c
+++ b/drivers/net/mlx4/alloc.c
@@ -151,6 +151,19 @@ int mlx4_buf_alloc(struct mlx4_dev *dev, int size, int max_direct,
 
                        memset(buf->u.page_list[i].buf, 0, PAGE_SIZE);
                }
+
+               if (BITS_PER_LONG == 64) {
+                       struct page **pages;
+                       pages = kmalloc(sizeof *pages * buf->nbufs, GFP_KERNEL);
+                       if (!pages)
+                               goto err_free;
+                       for (i = 0; i < buf->nbufs; ++i)
+                               pages[i] = virt_to_page(buf->u.page_list[i].buf);
+                       buf->u.direct.buf = vmap(pages, buf->nbufs, VM_MAP, PAGE_KERNEL);
+                       kfree(pages);
+                       if (!buf->u.direct.buf)
+                               goto err_free;
+               }
        }
 
        return 0;
@@ -170,6 +183,9 @@ void mlx4_buf_free(struct mlx4_dev *dev, int size, struct mlx4_buf *buf)
                dma_free_coherent(&dev->pdev->dev, size, buf->u.direct.buf,
                                  buf->u.direct.map);
        else {
+               if (BITS_PER_LONG == 64)
+                       vunmap(buf->u.direct.buf);
+
                for (i = 0; i < buf->nbufs; ++i)
                        if (buf->u.page_list[i].buf)
                                dma_free_coherent(&dev->pdev->dev, PAGE_SIZE,

diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
index a0afa75..6316077 100644 (file)
--- a/include/linux/mlx4/device.h
+++ b/include/linux/mlx4/device.h
@@ -189,7 +189,7 @@ struct mlx4_buf_list {
 };
 
 struct mlx4_buf {
-       union {
+       struct {
                struct mlx4_buf_list    direct;
                struct mlx4_buf_list   *page_list;
        } u;
@@ -310,7 +310,7 @@ int mlx4_buf_alloc(struct mlx4_dev *dev, int size, int max_direct,
 void mlx4_buf_free(struct mlx4_dev *dev, int size, struct mlx4_buf *buf);
 static inline void *mlx4_buf_offset(struct mlx4_buf *buf, int offset)
 {
-       if (buf->nbufs == 1)
+       if (BITS_PER_LONG == 64 || buf->nbufs == 1)
                return buf->u.direct.buf + offset;
        else
                return buf->u.page_list[offset >> PAGE_SHIFT].buf +