linux-kernel - RE: [PATCH v4 08/17] iommufd: Always setup MSI and anforce cc on kernel-managed domains

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: <BL1PR11MB527173DCAFA9DD1D9270A8D78CD8A@BL1PR11MB5271.namprd11.prod.outlook.com>
Date:   Mon, 23 Oct 2023 02:53:20 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Nicolin Chen <nicolinc@...dia.com>,
        Jason Gunthorpe <jgg@...dia.com>
CC:     "Liu, Yi L" <yi.l.liu@...el.com>,
        "joro@...tes.org" <joro@...tes.org>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>,
        "cohuck@...hat.com" <cohuck@...hat.com>,
        "eric.auger@...hat.com" <eric.auger@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "mjrosato@...ux.ibm.com" <mjrosato@...ux.ibm.com>,
        "chao.p.peng@...ux.intel.com" <chao.p.peng@...ux.intel.com>,
        "yi.y.sun@...ux.intel.com" <yi.y.sun@...ux.intel.com>,
        "peterx@...hat.com" <peterx@...hat.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "shameerali.kolothum.thodi@...wei.com" 
        <shameerali.kolothum.thodi@...wei.com>,
        "lulu@...hat.com" <lulu@...hat.com>,
        "suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
        "Duan, Zhenzhong" <zhenzhong.duan@...el.com>,
        "Martins, Joao" <joao.m.martins@...cle.com>
Subject: RE: [PATCH v4 08/17] iommufd: Always setup MSI and anforce cc on
 kernel-managed domains

> From: Nicolin Chen <nicolinc@...dia.com>
> Sent: Monday, October 23, 2023 8:18 AM
> 
> On Sat, Oct 21, 2023 at 01:38:04PM -0300, Jason Gunthorpe wrote:
> > On Fri, Oct 20, 2023 at 11:59:13AM -0700, Nicolin Chen wrote:
> > > On Fri, Oct 20, 2023 at 10:55:01AM -0300, Jason Gunthorpe wrote:
> > > > On Fri, Oct 20, 2023 at 02:43:58AM +0000, Tian, Kevin wrote:
> > > >
> > > > > But the user shouldn't assume such explicit consistency since it's not
> > > > > defined in our uAPI. All we defined is that the attaching may
> > > > > fail due to incompatibility for whatever reason then the user can
> > > > > always try creating a new hwpt for the to-be-attached device. From
> > > > > this regard I don't see providing consistency of result is
> > > > > necessary. 😊
> > > >
> > > > Anyhow, OK, lets add a comment summarizing your points and remove
> the
> > > > cc upgrade at attach time (sorry Nicolin/Yi!)
> > >
> > > Ack. I will send a small removal series. I assume it should CC
> > > stable tree also?
> >
> > No, it seems more like tidying that fixing a functional issue, do I
> > misunderstand?
> 
> Hmm. Maybe the misunderstanding is mine -- Kevin was asking if
> it was already a bug and you answered yes:
> https://lore.kernel.org/linux-iommu/20231016115736.GP3952@nvidia.com/
> 

currently intel-iommu driver already rejects 1) enforcing CC on
a domain which is already attached to non-CC device and
2) attaching a non-CC device to a domain which has enforce_cc.

so there is no explorable bug to fix in stable tree.

Just logically intel-iommu driver doesn't support enforcing Cc
on a domain which is capable of enforce-cc and already has
valid mappings. Then it should add proper check to prevent
it from being attempted by future usages.