Re: [PATCH v2 5/6] drm/i915: Don't clobber the GTT when it's within stolen memory

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Jun 30, 2014 at 01:25:29PM +0300, Jani Nikula wrote:
> On Thu, 05 Jun 2014, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > On most gen2-4 platforms the GTT can be (or maybe always is?)
> > inside the stolen memory region. If that's the case, reduce the
> > size of the stolen memory appropriately to make make sure we
> > don't clobber the GTT.
> >
> > v2: Deal with gen4 36 bit physical address
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=80151

Picked up for -fixes (with Chris' irc-ack and cc: stable), thanks for the
patch.
-Daniel

> 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_gem_stolen.c | 44 ++++++++++++++++++++++++++++++++++
> >  drivers/gpu/drm/i915/i915_reg.h        |  3 +++
> >  2 files changed, 47 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
> > index 62ef55b..7465ab0 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_stolen.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
> > @@ -74,6 +74,50 @@ static unsigned long i915_stolen_to_physical(struct drm_device *dev)
> >  	if (base == 0)
> >  		return 0;
> >  
> > +	/* make sure we don't clobber the GTT if it's within stolen memory */
> > +	if (INTEL_INFO(dev)->gen <= 4 && !IS_G33(dev) && !IS_G4X(dev)) {
> > +		struct {
> > +			u32 start, end;
> > +		} stolen[2] = {
> > +			{ .start = base, .end = base + dev_priv->gtt.stolen_size, },
> > +			{ .start = base, .end = base + dev_priv->gtt.stolen_size, },
> > +		};
> > +		u64 gtt_start, gtt_end;
> > +
> > +		gtt_start = I915_READ(PGTBL_CTL);
> > +		if (IS_GEN4(dev))
> > +			gtt_start = (gtt_start & PGTBL_ADDRESS_LO_MASK) |
> > +				(gtt_start & PGTBL_ADDRESS_HI_MASK) << 28;
> > +		else
> > +			gtt_start &= PGTBL_ADDRESS_LO_MASK;
> > +		gtt_end = gtt_start + gtt_total_entries(dev_priv->gtt) * 4;
> > +
> > +		if (gtt_start >= stolen[0].start && gtt_start < stolen[0].end)
> > +			stolen[0].end = gtt_start;
> > +		if (gtt_end > stolen[1].start && gtt_end <= stolen[1].end)
> > +			stolen[1].start = gtt_end;
> > +
> > +		/* pick the larger of the two chunks */
> > +		if (stolen[0].end - stolen[0].start >
> > +		    stolen[1].end - stolen[1].start) {
> > +			base = stolen[0].start;
> > +			dev_priv->gtt.stolen_size = stolen[0].end - stolen[0].start;
> > +		} else {
> > +			base = stolen[1].start;
> > +			dev_priv->gtt.stolen_size = stolen[1].end - stolen[1].start;
> > +		}
> > +
> > +		if (stolen[0].start != stolen[1].start ||
> > +		    stolen[0].end != stolen[1].end) {
> > +			DRM_DEBUG_KMS("GTT within stolen memory at 0x%llx-0x%llx\n",
> > +				      (unsigned long long) gtt_start,
> > +				      (unsigned long long) gtt_end - 1);
> > +			DRM_DEBUG_KMS("Stolen memory adjusted to 0x%x-0x%x\n",
> > +				      base, base + (u32) dev_priv->gtt.stolen_size - 1);
> > +		}
> > +	}
> > +
> > +
> >  	/* Verify that nothing else uses this physical address. Stolen
> >  	 * memory should be reserved by the BIOS and hidden from the
> >  	 * kernel. So if the region is already marked as busy, something
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 247be2a..619924b 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -978,6 +978,9 @@ enum punit_power_well {
> >  /*
> >   * Instruction and interrupt control regs
> >   */
> > +#define PGTBL_CTL	0x02020
> > +#define   PGTBL_ADDRESS_LO_MASK	0xfffff000 /* bits [31:12] */
> > +#define   PGTBL_ADDRESS_HI_MASK	0x000000f0 /* bits [35:32] (gen4) */
> >  #define PGTBL_ER	0x02024
> >  #define RENDER_RING_BASE	0x02000
> >  #define BSD_RING_BASE		0x04000
> > -- 
> > 1.8.5.5
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

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