Re: [PATCH] drm/i915: Sanitize the enable_ppgtt module option once

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Apr 22, 2014 at 10:22:15PM +0100, Chris Wilson wrote:
> On Tue, Apr 22, 2014 at 10:17:50PM +0200, Daniel Vetter wrote:
> > Otherwise we'll end up spamming dmesg on every context creation on snb
> > with vt-d enabled. This regression was introduced in
> > 
> > commit 246cbfb5fb9a1ca0997fbb135464c1ff5bb9c549
> > Author: Ben Widawsky <benjamin.widawsky@intel.com>
> > Date:   Fri Dec 6 14:11:14 2013 -0800
> > 
> >     drm/i915: Reorganize intel_enable_ppgtt
> 
> I started to consider what would happen if i915.enable_ppgtt changed on
> the fly, but then saw that it is 0400 and this pre-initialisation makes
> a lot of sense. So maybe we could mention that here:
> 
> As the i915.enable_ppgtt is read-only it cannot be changed after the
> module is loaded and so we can perform an early sanitization of the
> values.
> 
> > References: https://lkml.org/lkml/2014/4/17/599
> > Cc: Alessandro Suardi <alessandro.suardi@gmail.com>
> > Cc: Ben Widawsky <ben@bwidawsk.net>
> > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> If you care to add in some of the comments,
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

Fully agreed on both since the first thing I've checked is that the
enable_ppgtt option is indeed 0400 ;-)

Jani, can you please apply Chris' commit message text and comment when
merging?
-Daniel

> 
> >  drivers/gpu/drm/i915/i915_gem_gtt.c | 26 +++++++++++++++++++-------
> >  1 file changed, 19 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> > index 0d514ff9b94c..47491c4a1181 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> > @@ -34,25 +34,35 @@ static void gen8_setup_private_ppat(struct drm_i915_private *dev_priv);
> >  
> >  bool intel_enable_ppgtt(struct drm_device *dev, bool full)
> >  {
> > -	if (i915.enable_ppgtt == 0 || !HAS_ALIASING_PPGTT(dev))
> > +	if (i915.enable_ppgtt == 0)
> >  		return false;
> >  
> >  	if (i915.enable_ppgtt == 1 && full)
> >  		return false;
> >  
> > +	return true;
> > +}
> > +
> 
> /* i915.enable_ppgtt is read-only, so do an early pass to validate
>  * the user's requested state against the hardware/driver capabilities.
>  * We do this now so that we can print out any log messages once rather
>  * than every time we check intel_enable_ppgtt().
>  */
> > +static int sanitize_enable_ppgtt(struct drm_device *dev, int enable_ppgtt)
> > +{
> -Chris
> 
> -- 
> Chris Wilson, Intel Open Source Technology Centre

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch