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Subject: Re: [PATCH rdma-next 02/10] RDMA/core: Enable Relaxed Ordering in
 __ib_alloc_pd()
To:     Leon Romanovsky <leon@kernel.org>,
        Doug Ledford <dledford@redhat.com>,
        Jason Gunthorpe <jgg@nvidia.com>
Cc:     Avihai Horon <avihaih@nvidia.com>,
        Adit Ranadive <aditr@vmware.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        Ariel Elior <aelior@marvell.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Bernard Metzler <bmt@zurich.ibm.com>,
        Christoph Hellwig <hch@lst.de>,
        Chuck Lever <chuck.lever@oracle.com>,
        "David S. Miller" <davem@davemloft.net>,
        Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
        Devesh Sharma <devesh.sharma@broadcom.com>,
        Faisal Latif <faisal.latif@intel.com>,
        Jack Wang <jinpu.wang@ionos.com>,
        Jakub Kicinski <kuba@kernel.org>,
        "J. Bruce Fields" <bfields@fieldses.org>,
        Jens Axboe <axboe@fb.com>,
        Karsten Graul <kgraul@linux.ibm.com>,
        Keith Busch <kbusch@kernel.org>, Lijun Ou <oulijun@huawei.com>,
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        linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org,
        Max Gurtovoy <maxg@mellanox.com>,
        Max Gurtovoy <mgurtovoy@nvidia.com>,
        "Md. Haris Iqbal" <haris.iqbal@ionos.com>,
        Michael Guralnik <michaelgur@nvidia.com>,
        Michal Kalderon <mkalderon@marvell.com>,
        Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>,
        Naresh Kumar PBS <nareshkumar.pbs@broadcom.com>,
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        Steve French <sfrench@samba.org>,
        Trond Myklebust <trond.myklebust@hammerspace.com>,
        VMware PV-Drivers <pv-drivers@vmware.com>,
        Weihang Li <liweihang@huawei.com>,
        Yishai Hadas <yishaih@nvidia.com>,
        Zhu Yanjun <zyjzyj2000@gmail.com>
References: <20210405052404.213889-1-leon@kernel.org>
 <20210405052404.213889-3-leon@kernel.org>
From:   Tom Talpey <tom@talpey.com>
Message-ID: <befc60f3-d28a-5420-b381-0f408bd7cca9@talpey.com>
Date:   Mon, 5 Apr 2021 14:01:16 -0400
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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.