drm/i915/pxp: Implement PXP irq handler

The HW will generate a teardown interrupt when session termination is
required, which requires i915 to submit a terminating batch. Once the HW
is done with the termination it will generate another interrupt, at
which point it is safe to re-create the session.

Since the termination and re-creation flow is something we want to
trigger from the driver as well, use a common work function that can be
called both from the irq handler and from the driver set-up flows, which
has the addded benefit of allowing us to skip any extra locks because
the work itself serializes the operations.

v2: use struct completion instead of bool (Chris)
v3: drop locks, clean up functions and improve comments (Chris),
    move to common work function.
v4: improve comments, simplify wait logic (Rodrigo)
v5: unconditionally set interrupts, rename state_attacked var (Rodrigo)
v10: remove inclusion of intel_gt_types.h from intel_pxp.h (Jani)

Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Signed-off-by: Huang, Sean Z <sean.z.huang@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210924191452.1539378-10-alan.previn.teres.alexis@intel.com

1 files changed, 60 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp.c b/drivers/gpu/drm/i915/pxp/intel_pxp.c
index 6afa87f90eef..2e188217c3b7 100644
--- a/drivers/gpu/drm/i915/pxp/intel_pxp.c
+++ b/drivers/gpu/drm/i915/pxp/intel_pxp.c
@@ -2,7 +2,9 @@
 /*
  * Copyright(c) 2020 Intel Corporation.
  */
+#include <linux/workqueue.h>
 #include "intel_pxp.h"
+#include "intel_pxp_irq.h"
 #include "intel_pxp_session.h"
 #include "intel_pxp_tee.h"
 #include "gt/intel_context.h"
@@ -80,6 +82,16 @@ void intel_pxp_init(struct intel_pxp *pxp)
 
 	mutex_init(&pxp->tee_mutex);
 
+	/*
+	 * we'll use the completion to check if there is a termination pending,
+	 * so we start it as completed and we reinit it when a termination
+	 * is triggered.
+	 */
+	init_completion(&pxp->termination);
+	complete_all(&pxp->termination);
+
+	INIT_WORK(&pxp->session_work, intel_pxp_session_work);
+
 	ret = create_vcs_context(pxp);
 	if (ret)
 		return;
@@ -108,19 +120,61 @@ void intel_pxp_fini(struct intel_pxp *pxp)
 	destroy_vcs_context(pxp);
 }
 
-void intel_pxp_init_hw(struct intel_pxp *pxp)
+void intel_pxp_mark_termination_in_progress(struct intel_pxp *pxp)
 {
-	int ret;
+	pxp->arb_is_valid = false;
+	reinit_completion(&pxp->termination);
+}
+
+static void intel_pxp_queue_termination(struct intel_pxp *pxp)
+{
+	struct intel_gt *gt = pxp_to_gt(pxp);
+
+	/*
+	 * We want to get the same effect as if we received a termination
+	 * interrupt, so just pretend that we did.
+	 */
+	spin_lock_irq(&gt->irq_lock);
+	intel_pxp_mark_termination_in_progress(pxp);
+	pxp->session_events |= PXP_TERMINATION_REQUEST;
+	queue_work(system_unbound_wq, &pxp->session_work);
+	spin_unlock_irq(&gt->irq_lock);
+}
 
+/*
+ * the arb session is restarted from the irq work when we receive the
+ * termination completion interrupt
+ */
+int intel_pxp_wait_for_arb_start(struct intel_pxp *pxp)
+{
+	if (!intel_pxp_is_enabled(pxp))
+		return 0;
+
+	if (!wait_for_completion_timeout(&pxp->termination,
+					 msecs_to_jiffies(100)))
+		return -ETIMEDOUT;
+
+	if (!pxp->arb_is_valid)
+		return -EIO;
+
+	return 0;
+}
+
+void intel_pxp_init_hw(struct intel_pxp *pxp)
+{
 	kcr_pxp_enable(pxp_to_gt(pxp));
+	intel_pxp_irq_enable(pxp);
 
-	/* always emit a full termination to clean the state */
-	ret = intel_pxp_terminate_arb_session_and_global(pxp);
-	if (!ret)
-		intel_pxp_create_arb_session(pxp);
+	/*
+	 * the session could've been attacked while we weren't loaded, so
+	 * handle it as if it was and re-create it.
+	 */
+	intel_pxp_queue_termination(pxp);
 }
 
 void intel_pxp_fini_hw(struct intel_pxp *pxp)
 {
 	kcr_pxp_disable(pxp_to_gt(pxp));
+
+	intel_pxp_irq_disable(pxp);
 }