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

[Ben Widawsky <ben@bwidawsk.net>]

On Wed, Apr 23, 2014 at 09:18:03AM +0200, Daniel Vetter wrote:
> 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

Here as well:
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>



> 
> > 
> > >  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

-- 
Ben Widawsky, Intel Open Source Technology Center