1 files changed, 411 insertions, 0 deletions
diff --git a/drivers/misc/mic/cosm/cosm_scif_server.c b/drivers/misc/mic/cosm/cosm_scif_server.c
new file mode 100644
index 000000000..e94b7eac4
--- /dev/null
+++ b/drivers/misc/mic/cosm/cosm_scif_server.c
@@ -0,0 +1,411 @@
+/*
+ * Intel MIC Platform Software Stack (MPSS)
+ *
+ * Copyright(c) 2015 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * The full GNU General Public License is included in this distribution in
+ * the file called "COPYING".
+ *
+ * Intel MIC Coprocessor State Management (COSM) Driver
+ *
+ */
+#include <linux/kthread.h>
+#include <linux/sched/signal.h>
+
+#include "cosm_main.h"
+
+/*
+ * The COSM driver uses SCIF to communicate between the management node and the
+ * MIC cards. SCIF is used to (a) Send a shutdown command to the card (b)
+ * receive a shutdown status back from the card upon completion of shutdown and
+ * (c) receive periodic heartbeat messages from the card used to deduce if the
+ * card has crashed.
+ *
+ * A COSM server consisting of a SCIF listening endpoint waits for incoming
+ * connections from the card. Upon acceptance of the connection, a separate
+ * work-item is scheduled to handle SCIF message processing for that card. The
+ * life-time of this work-item is therefore the time from which the connection
+ * from a card is accepted to the time at which the connection is closed. A new
+ * work-item starts each time the card boots and is alive till the card (a)
+ * shuts down (b) is reset (c) crashes (d) cosm_client driver on the card is
+ * unloaded.
+ *
+ * From the point of view of COSM interactions with SCIF during card
+ * shutdown, reset and crash are as follows:
+ *
+ * Card shutdown
+ * -------------
+ * 1. COSM client on the card invokes orderly_poweroff() in response to SHUTDOWN
+ *    message from the host.
+ * 2. Card driver shutdown callback invokes scif_unregister_device(..) resulting
+ *    in scif_remove(..) getting called on the card
+ * 3. scif_remove -> scif_stop -> scif_handle_remove_node ->
+ *    scif_peer_unregister_device -> device_unregister for the host peer device
+ * 4. During device_unregister remove(..) method of cosm_client is invoked which
+ *    closes the COSM SCIF endpoint on the card. This results in a SCIF_DISCNCT
+ *    message being sent to host SCIF. SCIF_DISCNCT message processing on the
+ *    host SCIF sets the host COSM SCIF endpoint state to DISCONNECTED and wakes
+ *    up the host COSM thread blocked in scif_poll(..) resulting in
+ *    scif_poll(..)  returning EPOLLHUP.
+ * 5. On the card, scif_peer_release_dev is next called which results in an
+ *    SCIF_EXIT message being sent to the host and after receiving the
+ *    SCIF_EXIT_ACK from the host the peer device teardown on the card is
+ *    complete.
+ * 6. As part of the SCIF_EXIT message processing on the host, host sends a
+ *    SCIF_REMOVE_NODE to itself corresponding to the card being removed. This
+ *    starts a similar SCIF peer device teardown sequence on the host
+ *    corresponding to the card being shut down.
+ *
+ * Card reset
+ * ----------
+ * The case of interest here is when the card has not been previously shut down
+ * since most of the steps below are skipped in that case:
+
+ * 1. cosm_stop(..) invokes hw_ops->stop(..) method of the base PCIe driver
+ *    which unregisters the SCIF HW device resulting in scif_remove(..) being
+ *    called on the host.
+ * 2. scif_remove(..) calls scif_disconnect_node(..) which results in a
+ *    SCIF_EXIT message being sent to the card.
+ * 3. The card executes scif_stop() as part of SCIF_EXIT message
+ *    processing. This results in the COSM endpoint on the card being closed and
+ *    the SCIF host peer device on the card getting unregistered similar to
+ *    steps 3, 4 and 5 for the card shutdown case above. scif_poll(..) on the
+ *    host returns EPOLLHUP as a result.
+ * 4. On the host, card peer device unregister and SCIF HW remove(..) also
+ *    subsequently complete.
+ *
+ * Card crash
+ * ----------
+ * If a reset is issued after the card has crashed, there is no SCIF_DISCNT
+ * message from the card which would result in scif_poll(..) returning
+ * EPOLLHUP. In this case when the host SCIF driver sends a SCIF_REMOVE_NODE
+ * message to itself resulting in the card SCIF peer device being unregistered,
+ * this results in a scif_peer_release_dev -> scif_cleanup_scifdev->
+ * scif_invalidate_ep call sequence which sets the endpoint state to
+ * DISCONNECTED and results in scif_poll(..) returning EPOLLHUP.
+ */
+
+#define COSM_SCIF_BACKLOG 16
+#define COSM_HEARTBEAT_CHECK_DELTA_SEC 10
+#define COSM_HEARTBEAT_TIMEOUT_SEC \
+		(COSM_HEARTBEAT_SEND_SEC + COSM_HEARTBEAT_CHECK_DELTA_SEC)
+#define COSM_HEARTBEAT_TIMEOUT_MSEC (COSM_HEARTBEAT_TIMEOUT_SEC * MSEC_PER_SEC)
+
+static struct task_struct *server_thread;
+static scif_epd_t listen_epd;
+
+/* Publish MIC card's shutdown status to user space MIC daemon */
+static void cosm_update_mic_status(struct cosm_device *cdev)
+{
+	if (cdev->shutdown_status_int != MIC_NOP) {
+		cosm_set_shutdown_status(cdev, cdev->shutdown_status_int);
+		cdev->shutdown_status_int = MIC_NOP;
+	}
+}
+
+/* Store MIC card's shutdown status internally when it is received */
+static void cosm_shutdown_status_int(struct cosm_device *cdev,
+				     enum mic_status shutdown_status)
+{
+	switch (shutdown_status) {
+	case MIC_HALTED:
+	case MIC_POWER_OFF:
+	case MIC_RESTART:
+	case MIC_CRASHED:
+		break;
+	default:
+		dev_err(&cdev->dev, "%s %d Unexpected shutdown_status %d\n",
+			__func__, __LINE__, shutdown_status);
+		return;
+	};
+	cdev->shutdown_status_int = shutdown_status;
+	cdev->heartbeat_watchdog_enable = false;
+
+	if (cdev->state != MIC_SHUTTING_DOWN)
+		cosm_set_state(cdev, MIC_SHUTTING_DOWN);
+}
+
+/* Non-blocking recv. Read and process all available messages */
+static void cosm_scif_recv(struct cosm_device *cdev)
+{
+	struct cosm_msg msg;
+	int rc;
+
+	while (1) {
+		rc = scif_recv(cdev->epd, &msg, sizeof(msg), 0);
+		if (!rc) {
+			break;
+		} else if (rc < 0) {
+			dev_dbg(&cdev->dev, "%s: %d rc %d\n",
+				__func__, __LINE__, rc);
+			break;
+		}
+		dev_dbg(&cdev->dev, "%s: %d rc %d id 0x%llx\n",
+			__func__, __LINE__, rc, msg.id);
+
+		switch (msg.id) {
+		case COSM_MSG_SHUTDOWN_STATUS:
+			cosm_shutdown_status_int(cdev, msg.shutdown_status);
+			break;
+		case COSM_MSG_HEARTBEAT:
+			/* Nothing to do, heartbeat only unblocks scif_poll */
+			break;
+		default:
+			dev_err(&cdev->dev, "%s: %d unknown msg.id %lld\n",
+				__func__, __LINE__, msg.id);
+			break;
+		}
+	}
+}
+
+/* Publish crashed status for this MIC card */
+static void cosm_set_crashed(struct cosm_device *cdev)
+{
+	dev_err(&cdev->dev, "node alive timeout\n");
+	cosm_shutdown_status_int(cdev, MIC_CRASHED);
+	cosm_update_mic_status(cdev);
+}
+
+/* Send host time to the MIC card to sync system time between host and MIC */
+static void cosm_send_time(struct cosm_device *cdev)
+{
+	struct cosm_msg msg = { .id = COSM_MSG_SYNC_TIME };
+	struct timespec64 ts;
+	int rc;
+
+	ktime_get_real_ts64(&ts);
+	msg.timespec.tv_sec = ts.tv_sec;
+	msg.timespec.tv_nsec = ts.tv_nsec;
+
+	rc = scif_send(cdev->epd, &msg, sizeof(msg), SCIF_SEND_BLOCK);
+	if (rc < 0)
+		dev_err(&cdev->dev, "%s %d scif_send failed rc %d\n",
+			__func__, __LINE__, rc);
+}
+
+/*
+ * Close this cosm_device's endpoint after its peer endpoint on the card has
+ * been closed. In all cases except MIC card crash EPOLLHUP on the host is
+ * triggered by the client's endpoint being closed.
+ */
+static void cosm_scif_close(struct cosm_device *cdev)
+{
+	/*
+	 * Because SHUTDOWN_STATUS message is sent by the MIC cards in the
+	 * reboot notifier when shutdown is still not complete, we notify mpssd
+	 * to reset the card when SCIF endpoint is closed.
+	 */
+	cosm_update_mic_status(cdev);
+	scif_close(cdev->epd);
+	cdev->epd = NULL;
+	dev_dbg(&cdev->dev, "%s %d\n", __func__, __LINE__);
+}
+
+/*
+ * Set card state to ONLINE when a new SCIF connection from a MIC card is
+ * received. Normally the state is BOOTING when the connection comes in, but can
+ * be ONLINE if cosm_client driver on the card was unloaded and then reloaded.
+ */
+static int cosm_set_online(struct cosm_device *cdev)
+{
+	int rc = 0;
+
+	if (MIC_BOOTING == cdev->state || MIC_ONLINE == cdev->state) {
+		cdev->heartbeat_watchdog_enable = cdev->sysfs_heartbeat_enable;
+		cdev->epd = cdev->newepd;
+		if (cdev->state == MIC_BOOTING)
+			cosm_set_state(cdev, MIC_ONLINE);
+		cosm_send_time(cdev);
+		dev_dbg(&cdev->dev, "%s %d\n", __func__, __LINE__);
+	} else {
+		dev_warn(&cdev->dev, "%s %d not going online in state: %s\n",
+			 __func__, __LINE__, cosm_state_string[cdev->state]);
+		rc = -EINVAL;
+	}
+	/* Drop reference acquired by bus_find_device in the server thread */
+	put_device(&cdev->dev);
+	return rc;
+}
+
+/*
+ * Work function for handling work for a SCIF connection from a particular MIC
+ * card. It first sets the card state to ONLINE and then calls scif_poll to
+ * block on activity such as incoming messages on the SCIF endpoint. When the
+ * endpoint is closed, the work function exits, completing its life cycle, from
+ * MIC card boot to card shutdown/reset/crash.
+ */
+void cosm_scif_work(struct work_struct *work)
+{
+	struct cosm_device *cdev = container_of(work, struct cosm_device,
+						scif_work);
+	struct scif_pollepd pollepd;
+	int rc;
+
+	mutex_lock(&cdev->cosm_mutex);
+	if (cosm_set_online(cdev))
+		goto exit;
+
+	while (1) {
+		pollepd.epd = cdev->epd;
+		pollepd.events = EPOLLIN;
+
+		/* Drop the mutex before blocking in scif_poll(..) */
+		mutex_unlock(&cdev->cosm_mutex);
+		/* poll(..) with timeout on our endpoint */
+		rc = scif_poll(&pollepd, 1, COSM_HEARTBEAT_TIMEOUT_MSEC);
+		mutex_lock(&cdev->cosm_mutex);
+		if (rc < 0) {
+			dev_err(&cdev->dev, "%s %d scif_poll rc %d\n",
+				__func__, __LINE__, rc);
+			continue;
+		}
+
+		/* There is a message from the card */
+		if (pollepd.revents & EPOLLIN)
+			cosm_scif_recv(cdev);
+
+		/* The peer endpoint is closed or this endpoint disconnected */
+		if (pollepd.revents & EPOLLHUP) {
+			cosm_scif_close(cdev);
+			break;
+		}
+
+		/* Did we timeout from poll? */
+		if (!rc && cdev->heartbeat_watchdog_enable)
+			cosm_set_crashed(cdev);
+	}
+exit:
+	dev_dbg(&cdev->dev, "%s %d exiting\n", __func__, __LINE__);
+	mutex_unlock(&cdev->cosm_mutex);
+}
+
+/*
+ * COSM SCIF server thread function. Accepts incoming SCIF connections from MIC
+ * cards, finds the correct cosm_device to associate that connection with and
+ * schedules individual work items for each MIC card.
+ */
+static int cosm_scif_server(void *unused)
+{
+	struct cosm_device *cdev;
+	scif_epd_t newepd;
+	struct scif_port_id port_id;
+	int rc;
+
+	allow_signal(SIGKILL);
+
+	while (!kthread_should_stop()) {
+		rc = scif_accept(listen_epd, &port_id, &newepd,
+				 SCIF_ACCEPT_SYNC);
+		if (rc < 0) {
+			if (-ERESTARTSYS != rc)
+				pr_err("%s %d rc %d\n", __func__, __LINE__, rc);
+			continue;
+		}
+
+		/*
+		 * Associate the incoming connection with a particular
+		 * cosm_device, COSM device ID == SCIF node ID - 1
+		 */
+		cdev = cosm_find_cdev_by_id(port_id.node - 1);
+		if (!cdev)
+			continue;
+		cdev->newepd = newepd;
+		schedule_work(&cdev->scif_work);
+	}
+
+	pr_debug("%s %d Server thread stopped\n", __func__, __LINE__);
+	return 0;
+}
+
+static int cosm_scif_listen(void)
+{
+	int rc;
+
+	listen_epd = scif_open();
+	if (!listen_epd) {
+		pr_err("%s %d scif_open failed\n", __func__, __LINE__);
+		return -ENOMEM;
+	}
+
+	rc = scif_bind(listen_epd, SCIF_COSM_LISTEN_PORT);
+	if (rc < 0) {
+		pr_err("%s %d scif_bind failed rc %d\n",
+		       __func__, __LINE__, rc);
+		goto err;
+	}
+
+	rc = scif_listen(listen_epd, COSM_SCIF_BACKLOG);
+	if (rc < 0) {
+		pr_err("%s %d scif_listen rc %d\n", __func__, __LINE__, rc);
+		goto err;
+	}
+	pr_debug("%s %d listen_epd set up\n", __func__, __LINE__);
+	return 0;
+err:
+	scif_close(listen_epd);
+	listen_epd = NULL;
+	return rc;
+}
+
+static void cosm_scif_listen_exit(void)
+{
+	pr_debug("%s %d closing listen_epd\n", __func__, __LINE__);
+	if (listen_epd) {
+		scif_close(listen_epd);
+		listen_epd = NULL;
+	}
+}
+
+/*
+ * Create a listening SCIF endpoint and a server kthread which accepts incoming
+ * SCIF connections from MIC cards
+ */
+int cosm_scif_init(void)
+{
+	int rc = cosm_scif_listen();
+
+	if (rc) {
+		pr_err("%s %d cosm_scif_listen rc %d\n",
+		       __func__, __LINE__, rc);
+		goto err;
+	}
+
+	server_thread = kthread_run(cosm_scif_server, NULL, "cosm_server");
+	if (IS_ERR(server_thread)) {
+		rc = PTR_ERR(server_thread);
+		pr_err("%s %d kthread_run rc %d\n", __func__, __LINE__, rc);
+		goto listen_exit;
+	}
+	return 0;
+listen_exit:
+	cosm_scif_listen_exit();
+err:
+	return rc;
+}
+
+/* Stop the running server thread and close the listening SCIF endpoint */
+void cosm_scif_exit(void)
+{
+	int rc;
+
+	if (!IS_ERR_OR_NULL(server_thread)) {
+		rc = send_sig(SIGKILL, server_thread, 0);
+		if (rc) {
+			pr_err("%s %d send_sig rc %d\n",
+			       __func__, __LINE__, rc);
+			return;
+		}
+		kthread_stop(server_thread);
+	}
+
+	cosm_scif_listen_exit();
+}