linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] vdpa_sim: do not reset IOTLB during device reset
Date: Thu, 14 May 2020 05:35:27 -0400	[thread overview]
Message-ID: <20200514053233-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20200514072549.29694-1-jasowang@redhat.com>

On Thu, May 14, 2020 at 03:25:49PM +0800, Jason Wang wrote:
> We reset IOTLB during device reset this breaks the assumption that the
> mapping needs to be controlled via vDPA DMA ops explicitly in a
> incremental way. So the networking will be broken after e.g a guest
> reset.
> 
> Fix this by not resetting the IOTLB during device reset.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>


That's a bit weird, and can be a security risk if state
leaks between security domains through this.
And there's 0 chance any hardware implementation can
keep the translations around across resets - there
is simply nowhere to keep them.

IMHO we need a different way to make this work, simulator
needs to look like a hardware device as much as possible.


> ---
>  drivers/vdpa/vdpa_sim/vdpa_sim.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> index 7957d2d41fc4..cc5525743a25 100644
> --- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
> +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> @@ -119,8 +119,6 @@ static void vdpasim_reset(struct vdpasim *vdpasim)
>  	for (i = 0; i < VDPASIM_VQ_NUM; i++)
>  		vdpasim_vq_reset(&vdpasim->vqs[i]);
>  
> -	vhost_iotlb_reset(vdpasim->iommu);
> -
>  	vdpasim->features = 0;
>  	vdpasim->status = 0;
>  	++vdpasim->generation;
> -- 
> 2.20.1


  reply	other threads:[~2020-05-14  9:35 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-14  7:25 Jason Wang
2020-05-14  9:35 ` Michael S. Tsirkin [this message]
2020-05-15  3:02   ` Jason Wang

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200514053233-mutt-send-email-mst@kernel.org \
    --to=mst@redhat.com \
    --cc=jasowang@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=virtualization@lists.linux-foundation.org \
    --subject='Re: [PATCH] vdpa_sim: do not reset IOTLB during device reset' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).