[Intel-gfx] [PATCH 2/3] drm/i915/opregion: rvda is relative from opregion base in opregion 2.1+

[Jani Nikula]

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.

Fixes: 04ebaadb9f2d ("drm/i915/opregion: handle VBT sizes bigger than 6 KB")
Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
Cc: Imre Deak <imre.d...@intel.com>
Signed-off-by: Jani Nikula <jani.nik...@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 7e4152d97c45..c7d523da6631 100644
--- a/drivers/gpu/drm/i915/intel_opregion.c
+++ b/drivers/gpu/drm/i915/intel_opregion.c
@@ -121,7 +121,8 @@ 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;
@@ -961,9 +962,24 @@ int intel_opregion_setup(struct drm_i915_private *dev_priv)
 
        if (opregion->header->opregion_ver >= OPREGION_VERSION(2, 0) &&
            opregion->asle && 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->opregion_ver >= OPREGION_VERSION(2, 1)) {
+                       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)) {
@@ -973,6 +989,8 @@ 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

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