linux-kernel - RE: [RFC 16/20] vfio/type1: Export symbols for dma [un]map code sharing

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 for Android: free password hash cracker in your pocket

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

Message-ID: <BN9PR11MB54333F7E43C4A69E58DE5D978CA29@BN9PR11MB5433.namprd11.prod.outlook.com>
Date:   Wed, 22 Sep 2021 03:57:58 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Jason Gunthorpe <jgg@...dia.com>, "Liu, Yi L" <yi.l.liu@...el.com>
CC:     "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "hch@....de" <hch@....de>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "joro@...tes.org" <joro@...tes.org>,
        "jean-philippe@...aro.org" <jean-philippe@...aro.org>,
        "parav@...lanox.com" <parav@...lanox.com>,
        "lkml@...ux.net" <lkml@...ux.net>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "lushenming@...wei.com" <lushenming@...wei.com>,
        "eric.auger@...hat.com" <eric.auger@...hat.com>,
        "corbet@....net" <corbet@....net>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "yi.l.liu@...ux.intel.com" <yi.l.liu@...ux.intel.com>,
        "Tian, Jun J" <jun.j.tian@...el.com>, "Wu, Hao" <hao.wu@...el.com>,
        "Jiang, Dave" <dave.jiang@...el.com>,
        "jacob.jun.pan@...ux.intel.com" <jacob.jun.pan@...ux.intel.com>,
        "kwankhede@...dia.com" <kwankhede@...dia.com>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>,
        "david@...son.dropbear.id.au" <david@...son.dropbear.id.au>,
        "nicolinc@...dia.com" <nicolinc@...dia.com>
Subject: RE: [RFC 16/20] vfio/type1: Export symbols for dma [un]map code
 sharing

> From: Jason Gunthorpe <jgg@...dia.com>
> Sent: Wednesday, September 22, 2021 2:15 AM
> 
> On Sun, Sep 19, 2021 at 02:38:44PM +0800, Liu Yi L wrote:
> > [HACK. will fix in v2]
> >
> > There are two options to impelement vfio type1v2 mapping semantics in
> > /dev/iommu.
> >
> > One is to duplicate the related code from vfio as the starting point,
> > and then merge with vfio type1 at a later time. However
> vfio_iommu_type1.c
> > has over 3000LOC with ~80% related to dma management logic, including:
> 
> I can't really see a way forward like this. I think some scheme to
> move the vfio datastructure is going to be necessary.
> 
> > - the dma map/unmap metadata management
> > - page pinning, and related accounting
> > - iova range reporting
> > - dirty bitmap retrieving
> > - dynamic vaddr update, etc.
> 
> All of this needs to be part of the iommufd anyhow..

yes

> 
> > The alternative is to consolidate type1v2 logic in /dev/iommu immediately,
> > which requires converting vfio_iommu_type1 to be a shim driver.
> 
> Another choice is the the datastructure coulde move and the two
> drivers could share its code and continue to exist more independently
> 

where to put the shared code?

btw this is one major open that I plan to discuss in LPC. 😊