drm/i915: Serialise access to GFX_FLSH_CNTL

Now that many threads may try to use the same mmio to flush the global
buffers after updating the PTE, serialise access to the mmio to prevent
concurrent access on gen7.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191130162320.1683424-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -123,6 +123,16 @@ static void gen6_ggtt_invalidate(struct i915_ggtt *ggtt)
 {
 	struct intel_uncore *uncore = ggtt->vm.gt->uncore;
 
+	spin_lock_irq(&uncore->lock);
+	intel_uncore_write_fw(uncore, GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
+	intel_uncore_read_fw(uncore, GFX_FLSH_CNTL_GEN6);
+	spin_unlock_irq(&uncore->lock);
+}
+
+static void gen8_ggtt_invalidate(struct i915_ggtt *ggtt)
+{
+	struct intel_uncore *uncore = ggtt->vm.gt->uncore;
+
 	/*
 	 * Note that as an uncached mmio write, this will flush the
 	 * WCB of the writes into the GGTT before it triggers the invalidate.
@@ -135,7 +145,7 @@ static void guc_ggtt_invalidate(struct i915_ggtt *ggtt)
 	struct intel_uncore *uncore = ggtt->vm.gt->uncore;
 	struct drm_i915_private *i915 = ggtt->vm.i915;
 
-	gen6_ggtt_invalidate(ggtt);
+	gen8_ggtt_invalidate(ggtt);
 
 	if (INTEL_GEN(i915) >= 12)
 		intel_uncore_write_fw(uncore, GEN12_GUC_TLB_INV_CR,
@@ -3048,7 +3058,7 @@ static int gen8_gmch_probe(struct i915_ggtt *ggtt)
 			ggtt->vm.clear_range = bxt_vtd_ggtt_clear_range__BKL;
 	}
 
-	ggtt->invalidate = gen6_ggtt_invalidate;
+	ggtt->invalidate = gen8_ggtt_invalidate;
 
 	ggtt->vm.vma_ops.bind_vma    = ggtt_bind_vma;
 	ggtt->vm.vma_ops.unbind_vma  = ggtt_unbind_vma;
@@ -3288,7 +3298,7 @@ int i915_ggtt_enable_hw(struct drm_i915_private *dev_priv)
 
 void i915_ggtt_enable_guc(struct i915_ggtt *ggtt)
 {
-	GEM_BUG_ON(ggtt->invalidate != gen6_ggtt_invalidate);
+	GEM_BUG_ON(ggtt->invalidate != gen8_ggtt_invalidate);
 
 	ggtt->invalidate = guc_ggtt_invalidate;
 
@@ -3298,13 +3308,13 @@ void i915_ggtt_enable_guc(struct i915_ggtt *ggtt)
 void i915_ggtt_disable_guc(struct i915_ggtt *ggtt)
 {
 	/* XXX Temporary pardon for error unload */
-	if (ggtt->invalidate == gen6_ggtt_invalidate)
+	if (ggtt->invalidate == gen8_ggtt_invalidate)
 		return;
 
 	/* We should only be called after i915_ggtt_enable_guc() */
 	GEM_BUG_ON(ggtt->invalidate != guc_ggtt_invalidate);
 
-	ggtt->invalidate = gen6_ggtt_invalidate;
+	ggtt->invalidate = gen8_ggtt_invalidate;
 
 	ggtt->invalidate(ggtt);
 }