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Date: Wed, 21 Mar 2018 06:58:04 -0600
From: Alex Williamson <alex.williamson@redhat.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: intel-gvt-dev@lists.freedesktop.org,
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Subject: Re: [PATCH v2] drm/i915/gvt: throw error on unhandled vfio ioctls
Message-ID: <20180321065804.5f818765@t450s.home>
In-Reply-To: <20180321090804.22430-1-kraxel@redhat.com>
References: <20180321090804.22430-1-kraxel@redhat.com>
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On Wed, 21 Mar 2018 10:08:03 +0100
Gerd Hoffmann <kraxel@redhat.com> wrote:

> On unknown/unhandled ioctls the driver should return an error, so
> userspace knows it tried to use something unsupported.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  drivers/gpu/drm/i915/gvt/kvmgt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index 021f722e24..be881d53c2 100644
> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> @@ -1284,7 +1284,7 @@ static long intel_vgpu_ioctl(struct mdev_device *mdev, unsigned int cmd,
>  
>  	}
>  
> -	return 0;
> +	return -EINVAL;
>  }
>  
>  static ssize_t

Absolutely, but I'd prefer to continue the standard behavior among
other vfio drivers, and adopted from elsewhere in the kernel, to use
-ENOTTY for an unhandled ioctl, reserving -EINVAL as an error in
options for a supported ioctl.  Thanks,

Alex