linux-kernel - Re: [RFC PATCH 00/28] Removing struct page from P2PDMA

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: <20190627090154.GA11548@lst.de>
Date:   Thu, 27 Jun 2019 11:01:54 +0200
From:   Christoph Hellwig <hch@....de>
To:     Logan Gunthorpe <logang@...tatee.com>
Cc:     Christoph Hellwig <hch@....de>, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org, linux-nvme@...ts.infradead.org,
        linux-pci@...r.kernel.org, linux-rdma@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Keith Busch <kbusch@...nel.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Stephen Bates <sbates@...thlin.com>
Subject: Re: [RFC PATCH 00/28] Removing struct page from P2PDMA

On Wed, Jun 26, 2019 at 12:31:08PM -0600, Logan Gunthorpe wrote:
> > we have a hole behind len where we could store flag.  Preferably
> > optionally based on a P2P or other magic memory types config
> > option so that 32-bit systems with 32-bit phys_addr_t actually
> > benefit from the smaller and better packing structure.
> 
> That seems sensible. The one thing that's unclear though is how to get
> the PCI Bus address when appropriate. Can we pass that in instead of the
> phys_addr with an appropriate flag? Or will we need to pass the actual
> physical address and then, at the map step, the driver has to some how
> lookup the PCI device to figure out the bus offset?

Yes, I think we'll need a lookup mechanism of some kind.