[Intel-gfx] [PATCH 1/2] drm/i915: Detect page faults during hangcheck

[Chris Wilson]

On Sandybridge+, the GPU provides the ERROR register for detecting page
faults. Hook this up to our hangcheck so that we can dump the error
state soon after such an event occurs. This would be better inside an
interrupt handler, but it serves a purpose here as it detects that our
initial context setup is invalid...

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_irq.c     | 5 +++++
 drivers/gpu/drm/i915/intel_uncore.c | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 7913a72ce30a..eb2149b941e4 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2969,6 +2969,11 @@ static void i915_hangcheck_elapsed(unsigned long data)
 	if (!i915.enable_hangcheck)
 		return;
 
+	if (INTEL_INFO(dev_priv)->gen >= 6 && I915_READ(ERROR_GEN6)) {
+		i915_handle_error(dev, false, "GPU reported a page fault");
+		I915_WRITE(ERROR_GEN6, 0);
+	}
+
 	for_each_ring(ring, dev_priv, i) {
 		u64 acthd;
 		u32 seqno;
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 0655b44651a7..67f2e24c5bc5 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -535,6 +535,8 @@ static void __intel_uncore_early_sanitize(struct drm_device *dev,
 	if (IS_GEN6(dev) || IS_GEN7(dev))
 		__raw_i915_write32(dev_priv, GTFIFODBG,
 				   __raw_i915_read32(dev_priv, GTFIFODBG));
+	if (INTEL_INFO(dev)->gen >= 6)
+		__raw_i915_write32(dev_priv, ERROR_GEN6, 0);
 
 	intel_uncore_forcewake_reset(dev, restore_forcewake);
 }
-- 
2.1.3