IB/mlx5: Added support for re-registration of MRs

This patch adds support for re-registration of memory regions in MLX5.
The functionality is basically the same as deregister followed by
register, but attempts to reuse the existing resources as much as
possible.
Original memory keys are kept if possible, saving the need to
communicate new ones to remote peers.

Signed-off-by: Noa Osherovich <noaos@mellanox.com>
Reviewed-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 168 insertions, 0 deletions

diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 9d6dade31b5f..cf26cd1f1fa2 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -77,6 +77,12 @@ static int order2idx(struct mlx5_ib_dev *dev, int order)
 		return order - cache->ent[0].order;
 }
 
+static bool use_umr_mtt_update(struct mlx5_ib_mr *mr, u64 start, u64 length)
+{
+	return ((u64)1 << mr->order) * MLX5_ADAPTER_PAGE_SIZE >=
+		length + (start & (MLX5_ADAPTER_PAGE_SIZE - 1));
+}
+
 #ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
 static void update_odp_mr(struct mlx5_ib_mr *mr)
 {
@@ -1127,6 +1133,7 @@ static void set_mr_fileds(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr,
 	mr->ibmr.lkey = mr->mmr.key;
 	mr->ibmr.rkey = mr->mmr.key;
 	mr->ibmr.length = length;
+	mr->access_flags = access_flags;
 }
 
 struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
@@ -1222,6 +1229,167 @@ error:
 	return err;
 }
 
+static int rereg_umr(struct ib_pd *pd, struct mlx5_ib_mr *mr, u64 virt_addr,
+		     u64 length, int npages, int page_shift, int order,
+		     int access_flags, int flags)
+{
+	struct mlx5_ib_dev *dev = to_mdev(pd->device);
+	struct device *ddev = dev->ib_dev.dma_device;
+	struct mlx5_ib_umr_context umr_context;
+	struct ib_send_wr *bad;
+	struct mlx5_umr_wr umrwr = {};
+	struct ib_sge sg;
+	struct umr_common *umrc = &dev->umrc;
+	dma_addr_t dma = 0;
+	__be64 *mr_pas = NULL;
+	int size;
+	int err;
+
+	umrwr.wr.wr_id = (u64)(unsigned long)&umr_context;
+	umrwr.wr.send_flags = MLX5_IB_SEND_UMR_FAIL_IF_FREE;
+
+	if (flags & IB_MR_REREG_TRANS) {
+		err = dma_map_mr_pas(dev, mr->umem, npages, page_shift, &size,
+				     &mr_pas, &dma);
+		if (err)
+			return err;
+
+		umrwr.target.virt_addr = virt_addr;
+		umrwr.length = length;
+		umrwr.wr.send_flags |= MLX5_IB_SEND_UMR_UPDATE_TRANSLATION;
+	}
+
+	prep_umr_wqe_common(pd, &umrwr.wr, &sg, dma, npages, mr->mmr.key,
+			    page_shift);
+
+	if (flags & IB_MR_REREG_PD) {
+		umrwr.pd = pd;
+		umrwr.wr.send_flags |= MLX5_IB_SEND_UMR_UPDATE_PD;
+	}
+
+	if (flags & IB_MR_REREG_ACCESS) {
+		umrwr.access_flags = access_flags;
+		umrwr.wr.send_flags |= MLX5_IB_SEND_UMR_UPDATE_ACCESS;
+	}
+
+	mlx5_ib_init_umr_context(&umr_context);
+
+	/* post send request to UMR QP */
+	down(&umrc->sem);
+	err = ib_post_send(umrc->qp, &umrwr.wr, &bad);
+
+	if (err) {
+		mlx5_ib_warn(dev, "post send failed, err %d\n", err);
+	} else {
+		wait_for_completion(&umr_context.done);
+		if (umr_context.status != IB_WC_SUCCESS) {
+			mlx5_ib_warn(dev, "reg umr failed (%u)\n",
+				     umr_context.status);
+			err = -EFAULT;
+		}
+	}
+
+	up(&umrc->sem);
+	if (flags & IB_MR_REREG_TRANS) {
+		dma_unmap_single(ddev, dma, size, DMA_TO_DEVICE);
+		kfree(mr_pas);
+	}
+	return err;
+}
+
+int mlx5_ib_rereg_user_mr(struct ib_mr *ib_mr, int flags, u64 start,
+			  u64 length, u64 virt_addr, int new_access_flags,
+			  struct ib_pd *new_pd, struct ib_udata *udata)
+{
+	struct mlx5_ib_dev *dev = to_mdev(ib_mr->device);
+	struct mlx5_ib_mr *mr = to_mmr(ib_mr);
+	struct ib_pd *pd = (flags & IB_MR_REREG_PD) ? new_pd : ib_mr->pd;
+	int access_flags = flags & IB_MR_REREG_ACCESS ?
+			    new_access_flags :
+			    mr->access_flags;
+	u64 addr = (flags & IB_MR_REREG_TRANS) ? virt_addr : mr->umem->address;
+	u64 len = (flags & IB_MR_REREG_TRANS) ? length : mr->umem->length;
+	int page_shift = 0;
+	int npages = 0;
+	int ncont = 0;
+	int order = 0;
+	int err;
+
+	mlx5_ib_dbg(dev, "start 0x%llx, virt_addr 0x%llx, length 0x%llx, access_flags 0x%x\n",
+		    start, virt_addr, length, access_flags);
+
+	if (flags != IB_MR_REREG_PD) {
+		/*
+		 * Replace umem. This needs to be done whether or not UMR is
+		 * used.
+		 */
+		flags |= IB_MR_REREG_TRANS;
+		ib_umem_release(mr->umem);
+		mr->umem = mr_umem_get(pd, addr, len, access_flags, &npages,
+				       &page_shift, &ncont, &order);
+		if (IS_ERR(mr->umem)) {
+			err = PTR_ERR(mr->umem);
+			mr->umem = NULL;
+			return err;
+		}
+	}
+
+	if (flags & IB_MR_REREG_TRANS && !use_umr_mtt_update(mr, addr, len)) {
+		/*
+		 * UMR can't be used - MKey needs to be replaced.
+		 */
+		if (mr->umred) {
+			err = unreg_umr(dev, mr);
+			if (err)
+				mlx5_ib_warn(dev, "Failed to unregister MR\n");
+		} else {
+			err = destroy_mkey(dev, mr);
+			if (err)
+				mlx5_ib_warn(dev, "Failed to destroy MKey\n");
+		}
+		if (err)
+			return err;
+
+		mr = reg_create(ib_mr, pd, addr, len, mr->umem, ncont,
+				page_shift, access_flags);
+
+		if (IS_ERR(mr))
+			return PTR_ERR(mr);
+
+		mr->umred = 0;
+	} else {
+		/*
+		 * Send a UMR WQE
+		 */
+		err = rereg_umr(pd, mr, addr, len, npages, page_shift,
+				order, access_flags, flags);
+		if (err) {
+			mlx5_ib_warn(dev, "Failed to rereg UMR\n");
+			return err;
+		}
+	}
+
+	if (flags & IB_MR_REREG_PD) {
+		ib_mr->pd = pd;
+		mr->mmr.pd = to_mpd(pd)->pdn;
+	}
+
+	if (flags & IB_MR_REREG_ACCESS)
+		mr->access_flags = access_flags;
+
+	if (flags & IB_MR_REREG_TRANS) {
+		atomic_sub(mr->npages, &dev->mdev->priv.reg_pages);
+		set_mr_fileds(dev, mr, npages, len, access_flags);
+		mr->mmr.iova = addr;
+		mr->mmr.size = len;
+	}
+#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
+	update_odp_mr(mr);
+#endif
+
+	return 0;
+}
+
 static int
 mlx5_alloc_priv_descs(struct ib_device *device,
 		      struct mlx5_ib_mr *mr,