From: Yonatan Maman <yma...@nvidia.com>
Add support for P2P for MLX5 NIC devices with automatic fallback to
standard DMA when P2P mapping fails.
The change introduces P2P DMA requests by default using the
HMM_PFN_ALLOW_P2P flag. If P2P mapping fails with -EFAULT error, the
operation is retried without the P2P flag, ensuring a fallback to
standard DMA flow (using host memory).
Signed-off-by: Yonatan Maman <yma...@nvidia.com>
Signed-off-by: Gal Shalom <galsha...@nvidia.com>
---
drivers/infiniband/hw/mlx5/odp.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index f6abd64f07f7..6a0171117f48 100644
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -715,6 +715,10 @@ static int pagefault_real_mr(struct mlx5_ib_mr *mr, struct
ib_umem_odp *odp,
if (odp->umem.writable && !downgrade)
access_mask |= HMM_PFN_WRITE;
+ /*
+ * try fault with HMM_PFN_ALLOW_P2P flag
+ */
+ access_mask |= HMM_PFN_ALLOW_P2P;
np = ib_umem_odp_map_dma_and_lock(odp, user_va, bcnt, access_mask,
fault);
if (np < 0)
return np;
@@ -724,6 +728,18 @@ static int pagefault_real_mr(struct mlx5_ib_mr *mr, struct
ib_umem_odp *odp,
* ib_umem_odp_map_dma_and_lock already checks this.
*/
ret = mlx5r_umr_update_xlt(mr, start_idx, np, page_shift, xlt_flags);
+ if (ret == -EFAULT) {
+ /*
+ * Indicate P2P Mapping Error, retry with no HMM_PFN_ALLOW_P2P
+ */
+ mutex_unlock(&odp->umem_mutex);
+ access_mask &= ~(HMM_PFN_ALLOW_P2P);
+ np = ib_umem_odp_map_dma_and_lock(odp, user_va, bcnt,
access_mask, fault);
+ if (np < 0)
+ return np;
+ ret = mlx5r_umr_update_xlt(mr, start_idx, np, page_shift,
xlt_flags);
+ }
+
mutex_unlock(&odp->umem_mutex);
if (ret < 0) {
--
2.34.1
