linux-kernel - Re: [PATCH v6 00/20] Add VFIO mediated device support and DEV-MSI support for the idxd driver

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: <20210607191126.GP1002214@nvidia.com>
Date:   Mon, 7 Jun 2021 16:11:26 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Dave Jiang <dave.jiang@...el.com>
Cc:     "Tian, Kevin" <kevin.tian@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Kirti Wankhede <kwankhede@...dia.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "vkoul@...nel.org" <vkoul@...nel.org>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "Dey, Megha" <megha.dey@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>, "Lu, Baolu" <baolu.lu@...el.com>,
        "Kumar, Sanjay K" <sanjay.k.kumar@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        "eric.auger@...hat.com" <eric.auger@...hat.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH v6 00/20] Add VFIO mediated device support and DEV-MSI
 support for the idxd driver

On Mon, Jun 07, 2021 at 11:13:04AM -0700, Dave Jiang wrote:

> So in step 1, we 'tag' the wq to be dedicated to guest usage and put the
> hardware wq into enable state. For a dedicated mode wq, we can definitely
> just register directly and skip the mdev step. For a shared wq mode, we can
> have multiple mdev running on top of a single wq. So we need some way to
> create more mdevs. We can either go with the existing established creation
> path by mdev, or invent something custom for the driver as Jason suggested
> to accomodate additional virtual devices for guests. We implemented the mdev
> path originally with consideration of mdev is established and has a known
> interface already.

It sounds like you could just as easially have a 'create new vfio'
file under the idxd sysfs.. Especially since you already have a bus
and dynamic vfio specific things being created on this bus.

Have you gone over this with Dan?

> I think things become more complicated when we go from a dedicated wq to
> shared wq where the relationship of wq : mdev is 1 : 1 goes to 1 : N. Also
> needing to keep a consistent user config experience is desired, especially
> we already have such behavior since kernel 5.6 for host usages. So we really
> need try to avoid doing wq configuration differently just for "mdev" wqs. In
> the case suggested above, we basically just flipped the configuration steps.
> Mdev is first created through mdev sysfs interface. And then the device
> paramters are configured. Where for us, we configure the device parameter
> first, and then create the mdev. But in the end, it's still the hybrid mdev
> setup right?

So you don't even use mdev to configure anything? Yuk.

Jason