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: <6e1280c5-4b22-ebb3-3912-6c72bc169982@arm.com>
Date:   Wed, 22 Jun 2022 08:54:45 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Nicolin Chen <nicolinc@...dia.com>,
        "Tian, Kevin" <kevin.tian@...el.com>
Cc:     "joro@...tes.org" <joro@...tes.org>,
        "will@...nel.org" <will@...nel.org>,
        "marcan@...can.st" <marcan@...can.st>,
        "sven@...npeter.dev" <sven@...npeter.dev>,
        "robdclark@...il.com" <robdclark@...il.com>,
        "baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "orsonzhai@...il.com" <orsonzhai@...il.com>,
        "baolin.wang7@...il.com" <baolin.wang7@...il.com>,
        "zhang.lyra@...il.com" <zhang.lyra@...il.com>,
        "jean-philippe@...aro.org" <jean-philippe@...aro.org>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "jgg@...dia.com" <jgg@...dia.com>,
        "suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
        "alyssa@...enzweig.io" <alyssa@...enzweig.io>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "yong.wu@...iatek.com" <yong.wu@...iatek.com>,
        "mjrosato@...ux.ibm.com" <mjrosato@...ux.ibm.com>,
        "gerald.schaefer@...ux.ibm.com" <gerald.schaefer@...ux.ibm.com>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "vdumpa@...dia.com" <vdumpa@...dia.com>,
        "jonathanh@...dia.com" <jonathanh@...dia.com>,
        "cohuck@...hat.com" <cohuck@...hat.com>,
        "thunder.leizhen@...wei.com" <thunder.leizhen@...wei.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "christophe.jaillet@...adoo.fr" <christophe.jaillet@...adoo.fr>,
        "john.garry@...wei.com" <john.garry@...wei.com>,
        "chenxiang66@...ilicon.com" <chenxiang66@...ilicon.com>,
        "saiprakash.ranjan@...eaurora.org" <saiprakash.ranjan@...eaurora.org>,
        "isaacm@...eaurora.org" <isaacm@...eaurora.org>,
        "yangyingliang@...wei.com" <yangyingliang@...wei.com>,
        "jordan@...micpenguin.net" <jordan@...micpenguin.net>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH v2 3/5] vfio/iommu_type1: Remove the domain->ops
 comparison

On 2022-06-16 23:23, Nicolin Chen wrote:
> On Thu, Jun 16, 2022 at 06:40:14AM +0000, Tian, Kevin wrote:
> 
>>> The domain->ops validation was added, as a precaution, for mixed-driver
>>> systems. However, at this moment only one iommu driver is possible. So
>>> remove it.
>>
>> It's true on a physical platform. But I'm not sure whether a virtual platform
>> is allowed to include multiple e.g. one virtio-iommu alongside a virtual VT-d
>> or a virtual smmu. It might be clearer to claim that (as Robin pointed out)
>> there is plenty more significant problems than this to solve instead of simply
>> saying that only one iommu driver is possible if we don't have explicit code
>> to reject such configuration. 😊
> 
> Will edit this part. Thanks!

Oh, physical platforms with mixed IOMMUs definitely exist already. The 
main point is that while bus_set_iommu still exists, the core code 
effectively *does* prevent multiple drivers from registering - even in 
emulated cases like the example above, virtio-iommu and VT-d would both 
try to bus_set_iommu(&pci_bus_type), and one of them will lose. The 
aspect which might warrant clarification is that there's no combination 
of supported drivers which claim non-overlapping buses *and* could 
appear in the same system - even if you tried to contrive something by 
emulating, say, VT-d (PCI) alongside rockchip-iommu (platform), you 
could still only describe one or the other due to ACPI vs. Devicetree.

Thanks,
Robin.

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ