linux-kernel - Re: [for-next PATCH v5 03/11] RDMA: Extend RDMA kernel verbs ABI to support flush

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <942fdca3-2cd4-88d2-033c-6bd3f7bb258a@fujitsu.com>
Date:   Thu, 29 Sep 2022 14:21:24 +0800
From:   Li Zhijian <lizhijian@...itsu.com>
To:     Bob Pearson <rpearsonhpe@...il.com>,
        Leon Romanovsky <leon@...nel.org>,
        Jason Gunthorpe <jgg@...pe.ca>, linux-rdma@...r.kernel.org
Cc:     Zhu Yanjun <zyjzyj2000@...il.com>, yangx.jy@...itsu.com,
        y-goto@...itsu.com, mbloch@...dia.com, liangwenpeng@...wei.com,
        tom@...pey.com, tomasz.gromadzki@...el.com,
        dan.j.williams@...el.com, linux-kernel@...r.kernel.org
Subject: Re: [for-next PATCH v5 03/11] RDMA: Extend RDMA kernel verbs ABI to
 support flush

Leon, Jason


On 27/09/2022 13:53, Li Zhijian wrote:
>   /*
> @@ -4321,6 +4330,8 @@ int ib_dealloc_xrcd_user(struct ib_xrcd *xrcd, struct ib_udata *udata);
>   static inline int ib_check_mr_access(struct ib_device *ib_dev,
>   				     unsigned int flags)
>   {
> +	u64 device_cap = ib_dev->attrs.device_cap_flags;
> +
>   	/*
>   	 * Local write permission is required if remote write or
>   	 * remote atomic permission is also requested.
> @@ -4335,6 +4346,13 @@ static inline int ib_check_mr_access(struct ib_device *ib_dev,
>   	if (flags & IB_ACCESS_ON_DEMAND &&
>   	    !(ib_dev->attrs.kernel_cap_flags & IBK_ON_DEMAND_PAGING))
>   		return -EINVAL;
> +
> +	if ((flags & IB_ACCESS_FLUSH_GLOBAL &&
> +	    !(device_cap & IB_DEVICE_FLUSH_GLOBAL)) ||
> +	    (flags & IB_ACCESS_FLUSH_PERSISTENT &&
> +	    !(device_cap & IB_DEVICE_FLUSH_PERSISTENT)))
> +		return -EINVAL;
> +
Regarding of the return value of ib_check_mr_access. While updating the man page of ibv_reg_mr(3) of rdma-core,
```
        IBV_ACCESS_REMOTE_READ Enable Remote Read Access
        IBV_ACCESS_REMOTE_ATOMIC Enable Remote Atomic Operation Access (if supported)
        IBV_ACCESS_MW_BIND Enable Memory Window Binding
        IBV_ACCESS_ZERO_BASED  Use  byte offset from beginning of MR to access this MR, instead of a pointer address
        IBV_ACCESS_ON_DEMAND Create an on-demand paging MR (if supported)
...
RETURN VALUE
        ibv_reg_mr() / ibv_reg_mr_iova() / ibv_reg_dmabuf_mr() returns a pointer to the registered MR, or NULL if the request fails.  The local key (L_Key) field lkey is used as the lkey field of struct  ibv_sge  when  posting
        buffers  with  ibv_post_* verbs, and the the remote key (R_Key) field rkey is used by remote processes to perform Atomic and RDMA operations.  The remote process places this rkey as the rkey field of struct ibv_send_wr
        passed to the ibv_post_send function.
```
we can see, IBV_ACCESS_REMOTE_ATOMIC and IBV_ACCESS_ON_DEMAND are tagged "if supported" . but currently kernel
just returns EINVAL when user registers a MR with IB_ACCESS_ON_DEMAND to RXE.

I wonder we should return -EOPNOTSUPP if the device doesn't support requested capabilities

Thanks
Li


>   	return 0;
>   }
>