Re: [PATCH rdma-next 02/10] RDMA/core: Enable Relaxed Ordering in __ib_alloc_pd()

Tom Talpey
2021-04-05T18:01:31Z

On 4/5/2021 1:23 AM, Leon Romanovsky wrote:
> From: Avihai Horon <avihaih@nvidia.com>
>
> Enable Relaxed Ordering in __ib_alloc_pd() allocation of the
> local_dma_lkey.
>
> This will take effect only for devices that don't pre-allocate the lkey
> but allocate it per PD allocation.
>
> Signed-off-by: Avihai Horon <avihaih@nvidia.com>
> Reviewed-by: Michael Guralnik <michaelgur@nvidia.com>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
> drivers/infiniband/core/verbs.c | 3 ++-
> drivers/infiniband/hw/vmw_pvrdma/pvrdma_mr.c | 1 +
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
> index a1782f8a6ca0..9b719f7d6fd5 100644
> --- a/drivers/infiniband/core/verbs.c
> +++ b/drivers/infiniband/core/verbs.c
> @@ -287,7 +287,8 @@ struct ib_pd *__ib_alloc_pd(struct ib_device *device, unsigned int flags,
> if (device->attrs.device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY)
> pd->local_dma_lkey = device->local_dma_lkey;
> else
> - mr_access_flags |= IB_ACCESS_LOCAL_WRITE;
> + mr_access_flags |=
> + IB_ACCESS_LOCAL_WRITE | IB_ACCESS_RELAXED_ORDERING;

So, do local_dma_lkey's get relaxed ordering unconditionally?

> if (flags & IB_PD_UNSAFE_GLOBAL_RKEY) {
> pr_warn("%s: enabling unsafe global rkey\n", caller);
> diff --git a/drivers/infiniband/hw/vmw_pvrdma/pvrdma_mr.c b/drivers/infiniband/hw/vmw_pvrdma/pvrdma_mr.c
> index b3fa783698a0..d74827694f92 100644
> --- a/drivers/infiniband/hw/vmw_pvrdma/pvrdma_mr.c
> +++ b/drivers/infiniband/hw/vmw_pvrdma/pvrdma_mr.c
> @@ -66,6 +66,7 @@ struct ib_mr *pvrdma_get_dma_mr(struct ib_pd *pd, int acc)
> int ret;
>
> /* Support only LOCAL_WRITE flag for DMA MRs */
> + acc &= ~IB_ACCESS_RELAXED_ORDERING;
> if (acc & ~IB_ACCESS_LOCAL_WRITE) {
> dev_warn(&dev->pdev->dev,
> "unsupported dma mr access flags %#x\n", acc);

Why does the pvrdma driver require relaxed ordering to be off?

Tom.