drm/i915: Assert that the context-switch completion matches our context

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.
v3: Only check against lrc_desc (as this contains the hw_id check)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170123113132.18665-2-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 432ee495dec2288a33e47b893476fbaaf3d76a28..eceffe25c0221e02d9dcfbbaef7a9e2aaa8d44e9 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -595,6 +595,11 @@ 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) !=
+                                  upper_32_bits(intel_lr_context_descriptor(port[0].request->ctx,
+                                                                            engine)));
+
                        GEM_BUG_ON(port[0].count == 0);
                        if (--port[0].count == 0) {
                                GEM_BUG_ON(status & GEN8_CTX_STATUS_PREEMPTED);