linux-kernel - Re: [PATCH 09/12] nvme-pci: Use PCI p2pmem subsystem to manage the CMB

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: <a284e33f-c10d-0540-cd24-ad1993a042b6@deltatee.com>
Date:   Fri, 5 Jan 2018 11:14:38 -0700
From:   Logan Gunthorpe <logang@...tatee.com>
To:     Marta Rybczynska <mrybczyn@...ray.eu>
Cc:     linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-nvme@...ts.infradead.org, linux-rdma@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-block@...r.kernel.org,
        Stephen Bates <sbates@...thlin.com>,
        Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Keith Busch <keith.busch@...el.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Max Gurtovoy <maxg@...lanox.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCH 09/12] nvme-pci: Use PCI p2pmem subsystem to manage the
 CMB



On 05/01/18 08:30 AM, Marta Rybczynska wrote:
>> @@ -429,10 +429,7 @@ static void __nvme_submit_cmd(struct nvme_queue *nvmeq,
>> {
>> 	u16 tail = nvmeq->sq_tail;
>>
>> -	if (nvmeq->sq_cmds_io)
>> -		memcpy_toio(&nvmeq->sq_cmds_io[tail], cmd, sizeof(*cmd));
>> -	else
>> -		memcpy(&nvmeq->sq_cmds[tail], cmd, sizeof(*cmd));
>> +	memcpy(&nvmeq->sq_cmds[tail], cmd, sizeof(*cmd));
>>
> 
> Why is it always memcpy() and not memcpy_toio()? I'd expect something like
> if (nvmeq->sq_cmds_is_io)
> 	memcpy_toio(&nvmeq->sq_cmds_io[tail], cmd, sizeof(*cmd));
> else
> 	memcpy(&nvmeq->sq_cmds[tail], cmd, sizeof(*cmd));

We're going on the assumption that memory mapped with 
devm_memremap_pages() can be treated as regular memory. So memcpy_toio 
is not necessary for P2P memory.

Logan