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

From: Tom Talpey
Date: Mon Apr 05 2021 - 14:01:31 EST


On 4/5/2021 1:23 AM, Leon Romanovsky wrote:
From: Avihai Horon <avihaih@xxxxxxxxxx>

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@xxxxxxxxxx>
Reviewed-by: Michael Guralnik <michaelgur@xxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>
---
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.