drm/i915: fix TLB invalidation for Gen12 video and compute engines

In case of Gen12 video and compute engines, TLB_INV registers are masked -
to modify one bit, corresponding bit in upper half of the register must
be enabled, otherwise nothing happens.

CVE: CVE-2022-4139
Suggested-by: Chris Wilson <[email protected]>
Signed-off-by: Andrzej Hajda <[email protected]>
Acked-by: Daniel Vetter <[email protected]>
Fixes: 7938d61 ("drm/i915: Flush TLBs before releasing backing store")
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>

Author: ahajda

drivers/gpu/drm/i915/gt/intel_gt.c

@@ -1017,6 +1017,11 @@ static void mmio_invalidate_full(struct intel_gt *gt)
 		if (!i915_mmio_reg_offset(rb.reg))
 			continue;
 
+		if (GRAPHICS_VER(i915) == 12 && (engine->class == VIDEO_DECODE_CLASS ||
+		    engine->class == VIDEO_ENHANCEMENT_CLASS ||
+		    engine->class == COMPUTE_CLASS))
+			rb.bit = _MASKED_BIT_ENABLE(rb.bit);
+
 		intel_uncore_write_fw(uncore, rb.reg, rb.bit);
 		awake |= engine->mask;
 	}