[PATCH v2] 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 the Linux optee driver to 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@xxxxxxxxxx>
Cc: Sumit Garg <sumit.garg@xxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>

Co-developed-by: Alexandre Torgue <alexandre.torgue@xxxxxxxxxxx>
Signed-off-by: Alexandre Torgue <alexandre.torgue@xxxxxxxxxxx>
Signed-off-by: Etienne Carriere <etienne.carriere@xxxxxxxxxx>
---
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       | 107 ++++++++++++++++++++++++++++--
 2 files changed, 124 insertions(+), 5 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..ffa3f3aa7244 100644
--- a/drivers/tee/optee/smc_abi.c
+++ b/drivers/tee/optee/smc_abi.c
@@ -993,12 +993,20 @@ static u32 get_async_notif_value(optee_invoke_fn *invoke_fn, bool *value_valid,
 
 static irqreturn_t notif_irq_handler(int irq, void *dev_id)
 {
-	struct optee *optee = dev_id;
+	struct optee *optee;
 	bool do_bottom_half = false;
 	bool value_valid;
 	bool value_pending;
 	u32 value;
 
+	if (irq_is_percpu_devid(irq)) {
+		struct optee_pcpu __percpu *pcpu = (struct optee_pcpu *)dev_id;
+
+		optee = pcpu->optee;
+	} else {
+		optee = dev_id;
+	}
+
 	do {
 		value = get_async_notif_value(optee->smc.invoke_fn,
 					      &value_valid, &value_pending);
@@ -1011,8 +1019,13 @@ static irqreturn_t notif_irq_handler(int irq, void *dev_id)
 			optee_notif_send(optee, value);
 	} while (value_pending);
 
-	if (do_bottom_half)
-		return IRQ_WAKE_THREAD;
+	if (do_bottom_half) {
+		if (irq_is_percpu_devid(irq))
+			queue_work(optee->smc.notif_pcpu_wq, &optee->smc.notif_pcpu_work);
+		else
+			return IRQ_WAKE_THREAD;
+	}
+
 	return IRQ_HANDLED;
 }
 
@@ -1025,7 +1038,7 @@ 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 +1053,96 @@ static int optee_smc_notif_init_irq(struct optee *optee, u_int irq)
 	return 0;
 }
 
+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;
+	spinlock_t lock;
+	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_irq_handler,
+				"optee_pcpu_notification", optee_pcpu);
+	if (rc)
+		goto err_free_pcpu;
+
+	spin_lock_init(&lock);
+
+	spin_lock(&lock);
+	enable_percpu_irq(irq, 0);
+	spin_unlock(&lock);
+
+	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:
+	spin_lock(&lock);
+	disable_percpu_irq(irq);
+	spin_unlock(&lock);
+	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)
+{
+	spinlock_t lock;
+
+	spin_lock_init(&lock);
+	spin_lock(&lock);
+	disable_percpu_irq(optee->smc.notif_irq);
+	spin_unlock(&lock);
+
+	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