linux-kernel - Re: [PATCH v4 0/4] Implement vdpasim stop operation

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: <20220531013913-mutt-send-email-mst@kernel.org>
Date:   Tue, 31 May 2022 01:40:28 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     Parav Pandit <parav@...dia.com>,
        Eugenio Pérez <eperezma@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "martinh@...inx.com" <martinh@...inx.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        "martinpo@...inx.com" <martinpo@...inx.com>,
        "lvivier@...hat.com" <lvivier@...hat.com>,
        "pabloc@...inx.com" <pabloc@...inx.com>,
        Eli Cohen <elic@...dia.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Xie Yongji <xieyongji@...edance.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Zhang Min <zhang.min9@....com.cn>,
        Wu Zongyong <wuzongyong@...ux.alibaba.com>,
        "lulu@...hat.com" <lulu@...hat.com>,
        Zhu Lingshan <lingshan.zhu@...el.com>,
        "Piotr.Uminski@...el.com" <Piotr.Uminski@...el.com>,
        Si-Wei Liu <si-wei.liu@...cle.com>,
        "ecree.xilinx@...il.com" <ecree.xilinx@...il.com>,
        "gautam.dawar@....com" <gautam.dawar@....com>,
        "habetsm.xilinx@...il.com" <habetsm.xilinx@...il.com>,
        "tanuj.kamde@....com" <tanuj.kamde@....com>,
        "hanand@...inx.com" <hanand@...inx.com>,
        "dinang@...inx.com" <dinang@...inx.com>,
        Longpeng <longpeng2@...wei.com>
Subject: Re: [PATCH v4 0/4] Implement vdpasim stop operation

On Mon, May 30, 2022 at 11:39:21AM +0800, Jason Wang wrote:
> On Fri, May 27, 2022 at 6:56 PM Michael S. Tsirkin <mst@...hat.com> wrote:
> >
> > On Thu, May 26, 2022 at 12:54:32PM +0000, Parav Pandit wrote:
> > >
> > >
> > > > From: Eugenio Pérez <eperezma@...hat.com>
> > > > Sent: Thursday, May 26, 2022 8:44 AM
> > >
> > > > Implement stop operation for vdpa_sim devices, so vhost-vdpa will offer
> > > >
> > > > that backend feature and userspace can effectively stop the device.
> > > >
> > > >
> > > >
> > > > This is a must before get virtqueue indexes (base) for live migration,
> > > >
> > > > since the device could modify them after userland gets them. There are
> > > >
> > > > individual ways to perform that action for some devices
> > > >
> > > > (VHOST_NET_SET_BACKEND, VHOST_VSOCK_SET_RUNNING, ...) but there
> > > > was no
> > > >
> > > > way to perform it for any vhost device (and, in particular, vhost-vdpa).
> > > >
> > > >
> > > >
> > > > After the return of ioctl with stop != 0, the device MUST finish any
> > > >
> > > > pending operations like in flight requests. It must also preserve all
> > > >
> > > > the necessary state (the virtqueue vring base plus the possible device
> > > >
> > > > specific states) that is required for restoring in the future. The
> > > >
> > > > device must not change its configuration after that point.
> > > >
> > > >
> > > >
> > > > After the return of ioctl with stop == 0, the device can continue
> > > >
> > > > processing buffers as long as typical conditions are met (vq is enabled,
> > > >
> > > > DRIVER_OK status bit is enabled, etc).
> > >
> > > Just to be clear, we are adding vdpa level new ioctl() that doesn’t map to any mechanism in the virtio spec.
> > >
> > > Why can't we use this ioctl() to indicate driver to start/stop the device instead of driving it through the driver_ok?
> > > This is in the context of other discussion we had in the LM series.
> >
> > If there's something in the spec that does this then let's use that.
> 
> Actually, we try to propose a independent feature here:
> 
> https://lists.oasis-open.org/archives/virtio-dev/202111/msg00020.html
> 
> Does it make sense to you?
> 
> Thanks

But I thought the LM patches are trying to replace all that?


> > Unfortunately the LM series seems to be stuck on moving
> > bits around with the admin virtqueue ...
> >
> > --
> > MST
> >