Re: [PATCH v3 2/3] drm/i915/opregion: rvda is relative from opregion base in opregion 2.1+

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Feb 08, 2019 at 09:00:59PM +0200, Jani Nikula wrote:
> On Fri, 08 Feb 2019, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> > On Fri, Feb 08, 2019 at 08:42:53PM +0200, Jani Nikula wrote:
> >> Starting from opregion version 2.1 (roughly corresponding to ICL+) the
> >> RVDA field is relative from the beginning of opregion, not absolute
> >> address.
> >> 
> >> Fix the error path while at it.
> >> 
> >> v2: Make relative vs. absolute conditional on the opregion version,
> >>     bumped for the purpose. Turned out there are machines relying on
> >>     absolute RVDA in the wild.
> >> 
> >> v3: Fix the version checks
> >> 
> >> Fixes: 04ebaadb9f2d ("drm/i915/opregion: handle VBT sizes bigger than 6 KB")
> >> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >> Cc: Imre Deak <imre.deak@intel.com>
> >> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> >> ---
> >>  drivers/gpu/drm/i915/intel_opregion.c | 24 +++++++++++++++++++++---
> >>  1 file changed, 21 insertions(+), 3 deletions(-)
> >> 
> >> diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
> >> index f1b841580521..5e00ee9270b5 100644
> >> --- a/drivers/gpu/drm/i915/intel_opregion.c
> >> +++ b/drivers/gpu/drm/i915/intel_opregion.c
> >> @@ -123,7 +123,8 @@ struct opregion_asle {
> >>  	u64 fdss;
> >>  	u32 fdsp;
> >>  	u32 stat;
> >> -	u64 rvda;	/* Physical address of raw vbt data */
> >> +	u64 rvda;	/* Physical (2.0) or relative from opregion (2.1+)
> >> +			 * address of raw VBT data. */
> >>  	u32 rvds;	/* Size of raw vbt data */
> >>  	u8 rsvd[58];
> >>  } __packed;
> >> @@ -964,9 +965,24 @@ int intel_opregion_setup(struct drm_i915_private *dev_priv)
> >>  
> >>  	if (opregion->header->over.major >= 2 && opregion->asle &&
> 
> Push this line to short term memory.

Stack overflow.

Series is
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> 
> >>  	    opregion->asle->rvda && opregion->asle->rvds) {
> >> -		opregion->rvda = memremap(opregion->asle->rvda,
> >> -					  opregion->asle->rvds,
> >> +		resource_size_t rvda = opregion->asle->rvda;
> >> +
> >> +		/*
> >> +		 * opregion 2.0: rvda is the physical VBT address.
> >> +		 *
> >> +		 * opregion 2.1+: rvda is unsigned, relative offset from
> >> +		 * opregion base, and should never point within opregion.
> >> +		 */
> >> +		if (opregion->header->over.major > 2 ||
> >> +		    opregion->header->over.minor >= 1) {
> >
> > What happens with version 1.1?
> 
> Pop. ;)
> 
> BR,
> Jani.
> 
> >
> >> +			WARN_ON(rvda < OPREGION_SIZE);
> >> +
> >> +			rvda += asls;
> >> +		}
> >> +
> >> +		opregion->rvda = memremap(rvda, opregion->asle->rvds,
> >>  					  MEMREMAP_WB);
> >> +
> >>  		vbt = opregion->rvda;
> >>  		vbt_size = opregion->asle->rvds;
> >>  		if (intel_bios_is_valid_vbt(vbt, vbt_size)) {
> >> @@ -976,6 +992,8 @@ int intel_opregion_setup(struct drm_i915_private *dev_priv)
> >>  			goto out;
> >>  		} else {
> >>  			DRM_DEBUG_KMS("Invalid VBT in ACPI OpRegion (RVDA)\n");
> >> +			memunmap(opregion->rvda);
> >> +			opregion->rvda = NULL;
> >>  		}
> >>  	}
> >>  
> >> -- 
> >> 2.20.1
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center

-- 
Ville Syrjälä
Intel
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