netdev - Re: [PATCH] vdpa/mlx5: Setup driver only if VIRTIO_CONFIG_S_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] [day] [month] [year] [list]

Date:   Tue, 8 Sep 2020 22:06:50 -0400 (EDT)
From:   Jason Wang <jasowang@...hat.com>
To:     Eli Cohen <elic@...dia.com>
Cc:     "Michael S. Tsirkin" <mst@...hat.com>, Cindy Lu <lulu@...hat.com>,
        virtualization@...ts.linux-foundation.org,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] vdpa/mlx5: Setup driver only if
 VIRTIO_CONFIG_S_DRIVER_OK



----- Original Message -----
> On Mon, Sep 07, 2020 at 06:53:23AM -0400, Jason Wang wrote:
> > 
> > 
> > ----- Original Message -----
> > > If the memory map changes before the driver status is
> > > VIRTIO_CONFIG_S_DRIVER_OK, don't attempt to create resources because it
> > > may fail. For example, if the VQ is not ready there is no point in
> > > creating resources.
> > > 
> > > Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5
> > > devices")
> > > Signed-off-by: Eli Cohen <elic@...dia.com>
> > > ---
> > >  drivers/vdpa/mlx5/net/mlx5_vnet.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > index 9df69d5efe8c..c89cd48a0aab 100644
> > > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > @@ -1645,6 +1645,9 @@ static int mlx5_vdpa_change_map(struct
> > > mlx5_vdpa_net
> > > *ndev, struct vhost_iotlb *
> > >  	if (err)
> > >  		goto err_mr;
> > >  
> > > +	if (!(ndev->mvdev.status & VIRTIO_CONFIG_S_DRIVER_OK))
> > > +		return 0;
> > > +
> > 
> > I'm not sure I get this.
> > 
> > It looks to me if set_map() is called before DRIVER_OK, we won't build
> > any mapping?
> > 
> What would prevent that? Is it some qemu logic you're relying upon?

Ok, I think the map is still there, we just avoid to create some
resources.

> With current qemu 5.1 with lack of batching support, I get plenty calls
> to set_map which result in calls to mlx5_vdpa_change_map().
> If that happens before VIRTIO_CONFIG_S_DRIVER_OK then Imay fail (in case
> I was not called to set VQs ready).

Right, this could be solved by adding the batched IOTLB updating.

Thanks

> 
> > 
> > >  	restore_channels_info(ndev);
> > >  	err = setup_driver(ndev);
> > >  	if (err)
> > > --
> > > 2.26.0
> > > 
> > > 
> > 
> 
>