linux-kernel - Re: [PATCH v6 15/18] drm/virtio: rework virtio_gpu_transfer_to_host

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Message-ID: <20190705140746.czs2e5ffryx2slxf@sirius.home.kraxel.org>
Date:   Fri, 5 Jul 2019 16:07:46 +0200
From:   Gerd Hoffmann <kraxel@...hat.com>
To:     Chia-I Wu <olvaffe@...il.com>
Cc:     ML dri-devel <dri-devel@...ts.freedesktop.org>,
        Gurchetan Singh <gurchetansingh@...omium.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:VIRTIO GPU DRIVER" 
        <virtualization@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 15/18] drm/virtio: rework
 virtio_gpu_transfer_to_host_ioctl fencing

> > > ... 3d case passes the objs list to virtio_gpu_cmd_transfer_to_host_3d,
> > > so it gets added to the vbuf and released when the command is finished.
> > Why doesn't this apply to virtio_gpu_cmd_transfer_to_host_2d?
> 
> Hmm, yes, makes sense to handle both the same way.
> 
> With virgl=off qemu processes the commands from the guest
> synchronously, so it'll work fine as-is.  So you can't hit
> the theoretical race window in practice.  But depending
> on that host-side implementation detail isn't a good idea
> indeed.

Branch with incremental fixes:
https://git.kraxel.org/cgit/linux/log/?h=drm-virtio-kill-ttm

I'll be offline three weeks now, will resume this when I'm back.

cheers,
  Gerd