[Intel-gfx] [PATCH v2] drm/i915: Assert that the context-switch completion matches our context

[Chris Wilson]

When execlists signals the context completion, it also provides the
context id for the status event. Assert that id matches the one we expect.

v2: The upper dword of the context status is a duplicate of the upper
dword from elsp submission (i.e. includes the group id as well as the
context id). Include this check as well.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 432ee495dec2..963b1888d8a0 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -595,6 +595,12 @@ static void intel_lrc_irq_handler(unsigned long data)
 			if (!(status & GEN8_CTX_STATUS_COMPLETED_MASK))
 				continue;
 
+			/* Check the context/desc id for this event matches */
+			GEM_BUG_ON(((readl(buf + 2 * idx + 1) & (MAX_CONTEXT_HW_ID-1)) !=
+				    port[0].request->ctx->hw_id));
+			GEM_BUG_ON(readl(buf + 2 * idx + 1) !=
+				   upper_32_bits(port[0].request->ctx->engine[engine->id].lrc_desc));
+
 			GEM_BUG_ON(port[0].count == 0);
 			if (--port[0].count == 0) {
 				GEM_BUG_ON(status & GEN8_CTX_STATUS_PREEMPTED);
-- 
2.11.0