[PATCH 05/15] RDMA/mlx5: Rework implicit_mr_get_data

Jason Gunthorpe
2019-10-09T16:10:11Z

This function is intended to loop across each MTT chunk in the implicit
parent that intersects the range [io_virt, io_virt+bnct). But it is has a
confusing construction, so:

- Consistently use imr and odp_imr to refer to the implicit parent
to avoid confusion with the normal mr and odp of the child
- Directly compute the inclusive start/end indexes by shifting. This is
clearer to understand the intent and avoids any errors from unaligned
values of addr
- Iterate directly over the range of MTT indexes, do not make a loop
out of goto
- Follow 'success oriented flow', with goto error unwind
- Directly calculate the range of idx's that need update_xlt
- Ensure that any leaf MR added to the interval tree always results in an
update to the XLT

Reviewed-by: Artemy Kovalyov <artemyko@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
---
drivers/infiniband/hw/mlx5/odp.c | 123 +++++++++++++++++--------------
1 file changed, 69 insertions(+), 54 deletions(-)

diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index 3de30317891a23..a56c627e25ae58 100644
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -479,78 +479,93 @@ static struct mlx5_ib_mr *implicit_mr_alloc(struct ib_pd *pd,
return ERR_PTR(err);
}

-static struct ib_umem_odp *implicit_mr_get_data(struct mlx5_ib_mr *mr,
- u64 io_virt, size_t bcnt)
+static struct mlx5_ib_mr *implicit_get_child_mr(struct mlx5_ib_mr *imr,
+ unsigned long idx)
{
- struct mlx5_ib_dev *dev = to_mdev(mr->ibmr.pd->device);
- struct ib_umem_odp *odp, *result = NULL;
- struct ib_umem_odp *odp_mr = to_ib_umem_odp(mr->umem);
- u64 addr = io_virt & MLX5_IMR_MTT_MASK;
- int nentries = 0, start_idx = 0, ret;
+ struct ib_umem_odp *odp;
struct mlx5_ib_mr *mtt;

- mutex_lock(&odp_mr->umem_mutex);
- odp = odp_lookup(addr, 1, mr);
+ odp = ib_umem_odp_alloc_child(to_ib_umem_odp(imr->umem),
+ idx * MLX5_IMR_MTT_SIZE,
+ MLX5_IMR_MTT_SIZE);
+ if (IS_ERR(odp))
+ return ERR_CAST(odp);

- mlx5_ib_dbg(dev, "io_virt:%llx bcnt:%zx addr:%llx odp:%p\n",
- io_virt, bcnt, addr, odp);
+ mtt = implicit_mr_alloc(imr->ibmr.pd, odp, 0, imr->access_flags);
+ if (IS_ERR(mtt)) {
+ ib_umem_odp_release(odp);
+ return mtt;
+ }

-next_mr:
- if (likely(odp)) {
- if (nentries)
- nentries++;
- } else {
- odp = ib_umem_odp_alloc_child(odp_mr, addr, MLX5_IMR_MTT_SIZE);
- if (IS_ERR(odp)) {
- mutex_unlock(&odp_mr->umem_mutex);
- return ERR_CAST(odp);
- }
+ odp->private = mtt;
+ mtt->umem = &odp->umem;
+ mtt->mmkey.iova = idx * MLX5_IMR_MTT_SIZE;
+ mtt->parent = imr;
+ INIT_WORK(&odp->work, mr_leaf_free_action);

- mtt = implicit_mr_alloc(mr->ibmr.pd, odp, 0,
- mr->access_flags);
- if (IS_ERR(mtt)) {
- mutex_unlock(&odp_mr->umem_mutex);
- ib_umem_odp_release(odp);
- return ERR_CAST(mtt);
- }
+ xa_store(&mtt->dev->odp_mkeys, mlx5_base_mkey(mtt->mmkey.key),
+ &mtt->mmkey, GFP_ATOMIC);
+ return mtt;
+}

- odp->private = mtt;
- mtt->umem = &odp->umem;
- mtt->mmkey.iova = addr;
- mtt->parent = mr;
- INIT_WORK(&odp->work, mr_leaf_free_action);
+static struct ib_umem_odp *implicit_mr_get_data(struct mlx5_ib_mr *imr,
+ u64 io_virt, size_t bcnt)
+{
+ struct ib_umem_odp *odp_imr = to_ib_umem_odp(imr->umem);
+ unsigned long end_idx = (io_virt + bcnt - 1) >> MLX5_IMR_MTT_SHIFT;
+ unsigned long idx = io_virt >> MLX5_IMR_MTT_SHIFT;
+ unsigned long inv_start_idx = end_idx + 1;
+ unsigned long inv_len = 0;
+ struct ib_umem_odp *result = NULL;
+ struct ib_umem_odp *odp;
+ int ret;

- xa_store(&dev->odp_mkeys, mlx5_base_mkey(mtt->mmkey.key),
- &mtt->mmkey, GFP_ATOMIC);
+ mutex_lock(&odp_imr->umem_mutex);
+ odp = odp_lookup(idx * MLX5_IMR_MTT_SIZE, 1, imr);
+ for (idx = idx; idx <= end_idx; idx++) {
+ if (unlikely(!odp)) {
+ struct mlx5_ib_mr *mtt;

- if (!nentries)
- start_idx = addr >> MLX5_IMR_MTT_SHIFT;
- nentries++;
- }
+ mtt = implicit_get_child_mr(imr, idx);
+ if (IS_ERR(mtt)) {
+ result = ERR_CAST(mtt);
+ goto out;
+ }
+ odp = to_ib_umem_odp(mtt->umem);
+ inv_start_idx = min(inv_start_idx, idx);
+ inv_len = idx - inv_start_idx + 1;
+ }

- /* Return first odp if region not covered by single one */
- if (likely(!result))
- result = odp;
+ /* Return first odp if region not covered by single one */
+ if (likely(!result))
+ result = odp;

- addr += MLX5_IMR_MTT_SIZE;
- if (unlikely(addr < io_virt + bcnt)) {
odp = odp_next(odp);
- if (odp && ib_umem_start(odp) != addr)
+ if (odp && ib_umem_start(odp) != idx * MLX5_IMR_MTT_SIZE)
odp = NULL;
- goto next_mr;
}

- if (unlikely(nentries)) {
- ret = mlx5_ib_update_xlt(mr, start_idx, nentries, 0,
- MLX5_IB_UPD_XLT_INDIRECT |
+ /*
+ * Any time the children in the interval tree are changed we must
+ * perform an update of the xlt before exiting to ensure the HW and
+ * the tree remains synchronized.
+ */
+out:
+ if (likely(!inv_len))
+ goto out_unlock;
+
+ ret = mlx5_ib_update_xlt(imr, inv_start_idx, inv_len, 0,
+ MLX5_IB_UPD_XLT_INDIRECT |
MLX5_IB_UPD_XLT_ATOMIC);
- if (ret) {
- mlx5_ib_err(dev, "Failed to update PAS\n");
- result = ERR_PTR(ret);
- }
+ if (ret) {
+ mlx5_ib_err(to_mdev(imr->ibmr.pd->device),
+ "Failed to update PAS\n");
+ result = ERR_PTR(ret);
+ goto out_unlock;
}

- mutex_unlock(&odp_mr->umem_mutex);
+out_unlock:
+ mutex_unlock(&odp_imr->umem_mutex);
return result;
}

--
2.23.0