Re: [PATCH v2 06/10] IB/core: Add optional PCI P2P flag to rdma_rw_ctx_[init|destroy]()

From: Sagi Grimberg
Date: Thu Mar 01 2018 - 05:32:59 EST




On 03/01/2018 01:40 AM, Logan Gunthorpe wrote:
In order to use PCI P2P memory pci_p2pmem_[un]map_sg() functions must be
called to map the correct DMA address. To do this, we add a flags
variable and the RDMA_RW_CTX_FLAG_PCI_P2P flag. When the flag is
specified use the appropriate map function.

Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
---
drivers/infiniband/core/rw.c | 21 +++++++++++++++++----
drivers/infiniband/ulp/isert/ib_isert.c | 5 +++--
drivers/infiniband/ulp/srpt/ib_srpt.c | 7 ++++---
drivers/nvme/target/rdma.c | 6 +++---
include/rdma/rw.h | 7 +++++--
net/sunrpc/xprtrdma/svc_rdma_rw.c | 6 +++---
6 files changed, 35 insertions(+), 17 deletions(-)

diff --git a/drivers/infiniband/core/rw.c b/drivers/infiniband/core/rw.c
index c8963e91f92a..775a9f8b15a6 100644
--- a/drivers/infiniband/core/rw.c
+++ b/drivers/infiniband/core/rw.c
@@ -12,6 +12,7 @@
*/
#include <linux/moduleparam.h>
#include <linux/slab.h>
+#include <linux/pci-p2pdma.h>
#include <rdma/mr_pool.h>
#include <rdma/rw.h>
@@ -269,18 +270,24 @@ static int rdma_rw_init_single_wr(struct rdma_rw_ctx *ctx, struct ib_qp *qp,
* @remote_addr:remote address to read/write (relative to @rkey)
* @rkey: remote key to operate on
* @dir: %DMA_TO_DEVICE for RDMA WRITE, %DMA_FROM_DEVICE for RDMA READ
+ * @flags: any of the RDMA_RW_CTX_FLAG_* flags
*
* Returns the number of WQEs that will be needed on the workqueue if
* successful, or a negative error code.
*/
int rdma_rw_ctx_init(struct rdma_rw_ctx *ctx, struct ib_qp *qp, u8 port_num,
struct scatterlist *sg, u32 sg_cnt, u32 sg_offset,
- u64 remote_addr, u32 rkey, enum dma_data_direction dir)
+ u64 remote_addr, u32 rkey, enum dma_data_direction dir,
+ unsigned int flags)
{
struct ib_device *dev = qp->pd->device;
int ret;
- ret = ib_dma_map_sg(dev, sg, sg_cnt, dir);
+ if (flags & RDMA_RW_CTX_FLAG_PCI_P2PDMA)
+ ret = pci_p2pdma_map_sg(dev->dma_device, sg, sg_cnt, dir);
+ else
+ ret = ib_dma_map_sg(dev, sg, sg_cnt, dir);
+

Why not use is_pci_p2pdma_page(sg) instead of a flag? It would be so
much cleaner...