Re: [RFC PATCH v2 2/2] RDMA/rxe: Support RDMA Atomic Write operation

From: "yangx.jy@fujitsu.com" <yangx.jy@fujitsu.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
	"tom@talpey.com" <tom@talpey.com>,
	"yanjun.zhu@linux.dev" <yanjun.zhu@linux.dev>,
	"rpearsonhpe@gmail.com" <rpearsonhpe@gmail.com>,
	"y-goto@fujitsu.com" <y-goto@fujitsu.com>,
	"lizhijian@fujitsu.com" <lizhijian@fujitsu.com>,
	"tomasz.gromadzki@intel.com" <tomasz.gromadzki@intel.com>
Subject: Re: [RFC PATCH v2 2/2] RDMA/rxe: Support RDMA Atomic Write operation
Date: Tue, 18 Jan 2022 09:03:55 +0000	[thread overview]
Message-ID: <61E68279.7040406@fujitsu.com> (raw)
In-Reply-To: <61E67499.4010408@fujitsu.com>

Hi,

Sorry for the duplicate replies.

Best Regards,
Xiao Yang
On 2022/1/18 16:04, yangx.jy@fujitsu.com wrote:
> On 2022/1/17 21:16, Jason Gunthorpe wrote:
>> On Thu, Jan 13, 2022 at 11:03:50AM +0800, Xiao Yang wrote:
>>> +static enum resp_states process_atomic_write(struct rxe_qp *qp,
>>> +					     struct rxe_pkt_info *pkt)
>>> +{
>>> +	struct rxe_mr *mr = qp->resp.mr;
>>> +
>>> +	u64 *src = payload_addr(pkt);
>>> +
>>> +	u64 *dst = iova_to_vaddr(mr, qp->resp.va + qp->resp.offset, sizeof(u64));
>>> +	if (!dst || (uintptr_t)dst&  7)
>>> +		return RESPST_ERR_MISALIGNED_ATOMIC;
>> It looks to me like iova_to_vaddr is completely broken, where is the
>> kmap on that flow?
> Hi Jason,
>
> I think rxe_mr_init_user() maps the user addr space to the kernel addr 
> space during memory region registration, the mapping records are saved 
> into mr->cur_map_set->map[x].
> Why do you think iova_to_vaddr() is completely broken?
>
> Best Regards,
> Xiao Yang
>> Jason