linux-kernel - Re: [PATCH v3 3/6] iommu: Add return value rules to attach

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: <YyoT/M+mFVqI5Y1T@Asurada-Nvidia>
Date:   Tue, 20 Sep 2022 12:26:52 -0700
From:   Nicolin Chen <nicolinc@...dia.com>
To:     "Tian, Kevin" <kevin.tian@...el.com>
CC:     "joro@...tes.org" <joro@...tes.org>,
        "suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
        "will@...nel.org" <will@...nel.org>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "robdclark@...il.com" <robdclark@...il.com>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "baolu.lu@...ux.intel.com" <baolu.lu@...ux.intel.com>,
        "agross@...nel.org" <agross@...nel.org>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "orsonzhai@...il.com" <orsonzhai@...il.com>,
        "baolin.wang@...ux.alibaba.com" <baolin.wang@...ux.alibaba.com>,
        "zhang.lyra@...il.com" <zhang.lyra@...il.com>,
        "jean-philippe@...aro.org" <jean-philippe@...aro.org>,
        "sricharan@...eaurora.org" <sricharan@...eaurora.org>,
        "jgg@...dia.com" <jgg@...dia.com>,
        "konrad.dybcio@...ainline.org" <konrad.dybcio@...ainline.org>,
        "yong.wu@...iatek.com" <yong.wu@...iatek.com>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "vdumpa@...dia.com" <vdumpa@...dia.com>,
        "jonathanh@...dia.com" <jonathanh@...dia.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "shameerali.kolothum.thodi@...wei.com" 
        <shameerali.kolothum.thodi@...wei.com>,
        "christophe.jaillet@...adoo.fr" <christophe.jaillet@...adoo.fr>,
        "thunder.leizhen@...wei.com" <thunder.leizhen@...wei.com>,
        "quic_saipraka@...cinc.com" <quic_saipraka@...cinc.com>,
        "jon@...id-run.com" <jon@...id-run.com>,
        "yangyingliang@...wei.com" <yangyingliang@...wei.com>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
        "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-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>
Subject: Re: [PATCH v3 3/6] iommu: Add return value rules to attach_dev op
 and APIs

On Tue, Sep 20, 2022 at 06:24:58AM +0000, Tian, Kevin wrote:
> External email: Use caution opening links or attachments
> 
> 
> > From: Nicolin Chen <nicolinc@...dia.com>
> > Sent: Thursday, September 15, 2022 3:54 PM
> >
> > +/**
> > + * iommu_attach_device - Attach a device to an IOMMU domain
> > + * @domain: IOMMU domain to attach
> > + * @dev: Device that will be attached
> > + *
> > + * Returns 0 on success and error code on failure
> > + *
> > + * Note that EINVAL may be returned as a soft failure if the domain and
> > device
> > + * are incompatible: if the domain has already been used or configured in
> > some
> 
> I didn't get the meaning of the 'if' part.

It means that the failure of attaching the device to the domain is
due to the domain configuration.

> > + * way, attaching the same device to a different domain may succeed.
> > Otherwise,
> > + * it may still represent some fundamental problem.
> 
> I'm not sure what the sentence after 'otherwise' actually adds to the
> caller. There is no way to differentiate incompatibility vs. fundamental
> problem, hence pointless for the caller to know this fact.
> 
> IMHO just state that the caller can treat -EINVAL as soft failure indicating
> incompatibility issue between domain and device.

OK. I changed to:
+ * Note that EINVAL may be returned as a soft failure if the domain and device
+ * are incompatible due to some previous configuration of the domain, in which
+ * case attaching the same device to a different domain may succeed.

> Later for @attach_dev you can add that driver may return (but not
> recommend) -EINVAL for some fundamental problems.

OK.