linux-kernel - Re: [PATCH v6] drm/virtio: Add option to disable KMS support

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Message-ID: <20230303072705.55fbvt4c4uu4i2i7@sirius.home.kraxel.org>
Date:   Fri, 3 Mar 2023 08:27:05 +0100
From:   Gerd Hoffmann <kraxel@...hat.com>
To:     Rob Clark <robdclark@...il.com>
Cc:     dri-devel@...ts.freedesktop.org, Chia-I Wu <olvaffe@...il.com>,
        Ryan Neph <ryanneph@...omium.org>,
        Dmitry Osipenko <dmitry.osipenko@...labora.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Clark <robdclark@...omium.org>,
        Javier Martinez Canillas <javierm@...hat.com>,
        David Airlie <airlied@...hat.com>,
        Gurchetan Singh <gurchetansingh@...omium.org>,
        "open list:VIRTIO GPU DRIVER" 
        <virtualization@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6] drm/virtio: Add option to disable KMS support

On Thu, Mar 02, 2023 at 03:35:06PM -0800, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.org>
> 
> Add a build option to disable modesetting support.  This is useful in
> cases where the guest only needs to use the GPU in a headless mode, or
> (such as in the CrOS usage) window surfaces are proxied to a host
> compositor.
> 
> As the modesetting ioctls are a big surface area for potential security
> bugs to be found (it's happened in the past, we should assume it will
> again in the future), it makes sense to have a build option to disable
> those ioctls in cases where they serve no legitimate purpose.
> 
> v2: Use more if (IS_ENABLED(...))
> v3: Also permit the host to advertise no scanouts
> v4: Spiff out commit msg
> v5: Make num_scanouts==0 and DRM_VIRTIO_GPU_KMS=n behave the same
> v6: Drop conditionally building virtgpu_display.c and early-out of
>     it's init/fini fxns instead

Reviewed-by: Gerd Hoffmann <kraxel@...hat.com>