[PATCH v3] optee: add per cpu asynchronous notification

[Etienne Carriere]

Implements use of per-cpu irq for optee asynchronous notification.

Existing optee async notif implementation allows OP-TE world to
raise an interrupt for which Linux optee driver will query pending
events bound to waiting tasks in Linux world or threaded bottom half
tasks to be invoked in TEE world. This change allows the signaling
interrupt to be a per-cpu interrupt as with Arm GIC PPIs.

Cc: Jens Wiklander <jens.wiklander at linaro.org>
Cc: Sumit Garg <sumit.garg at linaro.org>
Cc: Marc Zyngier <maz at kernel.org>

Co-developed-by: Alexandre Torgue <alexandre.torgue at foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue at foss.st.com>
Signed-off-by: Etienne Carriere <etienne.carriere at linaro.org>
---
Changes since v2:
- Irq and per-cpu irq no more share the primary same handler function
  but have a common irq_handler() helper function.
- Removed useless spinlocks.
- Wrapped lines > 80 char.

Changes since v1:
- Fixed missing __percpu attribute reported by kernel test robot.
- Rephrased commit message and added Cc tags.
---
 drivers/tee/optee/optee_private.h | 22 +++++++
 drivers/tee/optee/smc_abi.c       | 97 +++++++++++++++++++++++++++++--
 2 files changed, 115 insertions(+), 4 deletions(-)

diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h
index 04ae58892608..e5bd3548691f 100644
--- a/drivers/tee/optee/optee_private.h
+++ b/drivers/tee/optee/optee_private.h
@@ -94,11 +94,33 @@ struct optee_supp {
 	struct completion reqs_c;
 };
 
+/*
+ * struct optee_pcpu - per cpu notif private struct passed to work functions
+ * @optee		optee device reference
+ */
+struct optee_pcpu {
+	struct optee *optee;
+};
+
+/*
+ * struct optee_smc - optee smc communication struct
+ * @invoke_fn		handler function to invoke secure monitor
+ * @memremaped_shm	virtual address of memory in shared memory pool
+ * @sec_caps:		secure world capabilities defined by
+ *			OPTEE_SMC_SEC_CAP_* in optee_smc.h
+ * @notif_irq		interrupt used as async notification by OP-TEE or 0
+ * @optee_pcpu		per_cpu optee instance for per cpu work or NULL
+ * @notif_pcpu_wq	workqueue for per cpu aynchronous notification or NULL
+ * @notif_pcpu_work	work for per cpu asynchronous notification
+ */
 struct optee_smc {
 	optee_invoke_fn *invoke_fn;
 	void *memremaped_shm;
 	u32 sec_caps;
 	unsigned int notif_irq;
+	struct optee_pcpu __percpu *optee_pcpu;
+	struct workqueue_struct *notif_pcpu_wq;
+	struct work_struct notif_pcpu_work;
 };
 
 /**
diff --git a/drivers/tee/optee/smc_abi.c b/drivers/tee/optee/smc_abi.c
index a1c1fa1a9c28..eff35f66399e 100644
--- a/drivers/tee/optee/smc_abi.c
+++ b/drivers/tee/optee/smc_abi.c
@@ -991,9 +991,8 @@ static u32 get_async_notif_value(optee_invoke_fn *invoke_fn, bool *value_valid,
 	return res.a1;
 }
 
-static irqreturn_t notif_irq_handler(int irq, void *dev_id)
+static irqreturn_t irq_handler(struct optee *optee)
 {
-	struct optee *optee = dev_id;
 	bool do_bottom_half = false;
 	bool value_valid;
 	bool value_pending;
@@ -1016,6 +1015,11 @@ static irqreturn_t notif_irq_handler(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static irqreturn_t notif_irq_handler(int irq, void *dev_id)
+{
+	return irq_handler((struct optee *)dev_id);
+}
+
 static irqreturn_t notif_irq_thread_fn(int irq, void *dev_id)
 {
 	struct optee *optee = dev_id;
@@ -1025,7 +1029,7 @@ static irqreturn_t notif_irq_thread_fn(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static int optee_smc_notif_init_irq(struct optee *optee, u_int irq)
+static int init_irq(struct optee *optee, u_int irq)
 {
 	int rc;
 
@@ -1040,12 +1044,97 @@ static int optee_smc_notif_init_irq(struct optee *optee, u_int irq)
 	return 0;
 }
 
+static irqreturn_t notif_pcpu_irq_handler(int irq, void *dev_id)
+{
+	struct optee_pcpu __percpu *pcpu = (struct optee_pcpu *)dev_id;
+	struct optee *optee = pcpu->optee;
+
+	if (irq_handler(optee) == IRQ_WAKE_THREAD)
+		queue_work(optee->smc.notif_pcpu_wq,
+			   &optee->smc.notif_pcpu_work);
+
+	return IRQ_HANDLED;
+}
+
+static void notif_pcpu_irq_work_fn(struct work_struct *work)
+{
+	struct optee_smc *optee_smc = container_of(work, struct optee_smc,
+						   notif_pcpu_work);
+	struct optee *optee = container_of(optee_smc, struct optee, smc);
+
+	optee_smc_do_bottom_half(optee->ctx);
+}
+
+static int init_pcpu_irq(struct optee *optee, u_int irq)
+{
+	struct optee_pcpu __percpu *optee_pcpu;
+	int cpu;
+	int rc;
+
+	optee_pcpu = alloc_percpu(struct optee_pcpu);
+	if (!optee_pcpu)
+		return -ENOMEM;
+
+	for_each_present_cpu(cpu) {
+		struct optee_pcpu __percpu *p = per_cpu_ptr(optee_pcpu, cpu);
+
+		p->optee = optee;
+	}
+
+	rc = request_percpu_irq(irq, notif_pcpu_irq_handler,
+				"optee_pcpu_notification", optee_pcpu);
+	if (rc)
+		goto err_free_pcpu;
+
+	enable_percpu_irq(irq, 0);
+
+	INIT_WORK(&optee->smc.notif_pcpu_work, notif_pcpu_irq_work_fn);
+	optee->smc.notif_pcpu_wq = create_workqueue("optee_pcpu_notification");
+	if (!optee->smc.notif_pcpu_wq) {
+		rc = -EINVAL;
+		goto err_free_pcpu_irq;
+	}
+
+	optee->smc.optee_pcpu = optee_pcpu;
+	optee->smc.notif_irq = irq;
+
+	return 0;
+
+err_free_pcpu_irq:
+	disable_percpu_irq(irq);
+	free_percpu_irq(irq, optee_pcpu);
+err_free_pcpu:
+	free_percpu(optee_pcpu);
+
+	return rc;
+}
+
+static int optee_smc_notif_init_irq(struct optee *optee, u_int irq)
+{
+	if (irq_is_percpu_devid(irq))
+		return init_pcpu_irq(optee, irq);
+	else
+		return init_irq(optee, irq);
+}
+
+static void uninit_pcpu_irq(struct optee *optee)
+{
+	disable_percpu_irq(optee->smc.notif_irq);
+
+	free_percpu_irq(optee->smc.notif_irq, optee->smc.optee_pcpu);
+	free_percpu(optee->smc.optee_pcpu);
+}
+
 static void optee_smc_notif_uninit_irq(struct optee *optee)
 {
 	if (optee->smc.sec_caps & OPTEE_SMC_SEC_CAP_ASYNC_NOTIF) {
 		optee_smc_stop_async_notif(optee->ctx);
 		if (optee->smc.notif_irq) {
-			free_irq(optee->smc.notif_irq, optee);
+			if (irq_is_percpu_devid(optee->smc.notif_irq))
+				uninit_pcpu_irq(optee);
+			else
+				free_irq(optee->smc.notif_irq, optee);
+
 			irq_dispose_mapping(optee->smc.notif_irq);
 		}
 	}
-- 
2.25.1