[ofa-general] [PATCH 1 of 2] IB/mlx4: For 64-bit systems, use large virtually contiguous queue buffers (vmap)

[Jack Morgenstein]

IB/mlx4: For 64-bit systems, use large virtually contiguous queue buffers (rather than 2-layer).

Since kernel virtual memory is not a problem on 64-bit systems, there is no
reason to use a 2-layer page mapping scheme on such systems. Instead,
map the page list to a single virtually contiguous buffer, so that
can access buffer memory via direct indexing.

Signed-off-by: Michael S. Tsirkin <mst at dev.mellanox.co.il>
Signed-off-by: Jack Morgenstein <jackm at dev.mellanox.co.il>

---

Roland, this 2-patch series is based on your for-2.6.25 tree,
commit 9b73e76f3cf63379dcf45fcd4f112f5812418d0a

Index: infiniband/drivers/net/mlx4/alloc.c
===================================================================
--- infiniband.orig/drivers/net/mlx4/alloc.c	2008-01-22 18:41:14.000000000 +0200
+++ infiniband/drivers/net/mlx4/alloc.c	2008-01-27 10:52:21.000000000 +0200
@@ -151,6 +151,19 @@ int mlx4_buf_alloc(struct mlx4_dev *dev,
 
 			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,
 		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,
Index: infiniband/include/linux/mlx4/device.h
===================================================================
--- infiniband.orig/include/linux/mlx4/device.h	2008-01-27 10:44:25.000000000 +0200
+++ infiniband/include/linux/mlx4/device.h	2008-01-27 10:52:21.000000000 +0200
@@ -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;
Index: infiniband/drivers/infiniband/hw/mlx4/qp.c
===================================================================
--- infiniband.orig/drivers/infiniband/hw/mlx4/qp.c	2008-01-27 10:44:25.000000000 +0200
+++ infiniband/drivers/infiniband/hw/mlx4/qp.c	2008-01-27 10:52:21.000000000 +0200
@@ -96,7 +96,7 @@ static int is_qp0(struct mlx4_ib_dev *de
 
 static void *get_wqe(struct mlx4_ib_qp *qp, int offset)
 {
-	if (qp->buf.nbufs == 1)
+	if (BITS_PER_LONG == 64 || qp->buf.nbufs == 1)
 		return qp->buf.u.direct.buf + offset;
 	else
 		return qp->buf.u.page_list[offset >> PAGE_SHIFT].buf +