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Violators will be prosecuted for from ; Sun, 20 May 2018 20:04:51 -0600 From: Deb McLemore To: linuxppc-dev@lists.ozlabs.org Cc: Deb McLemore Subject: [PATCH v3] powerpc/powernv: Add queue mechanism for early messages Date: Sun, 20 May 2018 21:04:38 -0500 In-Reply-To: <87bmdfoh8x.fsf@concordia.ellerman.id.au> References: <87bmdfoh8x.fsf@concordia.ellerman.id.au> Message-Id: <1526868278-4204-1-git-send-email-debmc@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Problem being solved is when issuing a BMC soft poweroff during IPL, the poweroff was being lost so the machine would not poweroff. Opal messages were being received before the opal-power code registered its notifiers. Alternatives discussed (option #3 was chosen): 1 - Have opal_message_init() explicitly call opal_power_control_init() before it dequeues any OPAL messages (i.e. before we register the opal-msg IRQ handler). 2 - Introduce concept of critical message types and when we register handlers we track which message types have a registered handler, then defer the opal-msg IRQ registration until we have a handler registered for all the critical types. 3 - Buffering messages, if we receive a message and do not yet have a handler for that type, store the message and replay when a handler for that type is registered. Signed-off-by: Deb McLemore --- arch/powerpc/platforms/powernv/opal.c | 89 ++++++++++++++++++++++++++++++++++- 1 file changed, 87 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c index 48fbb41..b8cae0d 100644 --- a/arch/powerpc/platforms/powernv/opal.c +++ b/arch/powerpc/platforms/powernv/opal.c @@ -40,6 +40,16 @@ #include "powernv.h" +#define OPAL_MSG_QUEUE_MAX 16 + +struct opal_msg_node { + struct list_head list; + struct opal_msg msg; +}; + +static DEFINE_SPINLOCK(msg_list_lock); +static LIST_HEAD(msg_list); + /* /sys/firmware/opal */ struct kobject *opal_kobj; @@ -55,6 +65,8 @@ struct mcheck_recoverable_range { u64 recover_addr; }; +static int msg_list_size; + static struct mcheck_recoverable_range *mc_recoverable_range; static int mc_recoverable_range_len; @@ -231,6 +243,44 @@ static int __init opal_register_exception_handlers(void) } machine_early_initcall(powernv, opal_register_exception_handlers); +static void queue_replay_msg(void *msg) +{ + struct opal_msg_node *msg_node; + + if (msg_list_size < OPAL_MSG_QUEUE_MAX) { + msg_node = kzalloc(sizeof(*msg_node), GFP_ATOMIC); + if (msg_node) { + INIT_LIST_HEAD(&msg_node->list); + memcpy(&msg_node->msg, msg, sizeof(struct opal_msg)); + list_add_tail(&msg_node->list, &msg_list); + msg_list_size++; + } else + pr_warn_once("message queue no memory\n"); + + if (msg_list_size >= OPAL_MSG_QUEUE_MAX) + pr_warn_once("message queue full\n"); + } +} + +static void dequeue_replay_msg(enum opal_msg_type msg_type) +{ + /* msg_list_lock held in register to allow operation to complete */ + /* prior to any subsequent messages */ + + struct opal_msg_node *msg_node, *tmp; + + list_for_each_entry_safe(msg_node, tmp, &msg_list, list) { + if (be32_to_cpu(msg_node->msg.msg_type) != msg_type) + continue; + atomic_notifier_call_chain(&opal_msg_notifier_head[msg_type], + msg_type, + &msg_node->msg); + list_del(&msg_node->list); + kfree(msg_node); + msg_list_size--; + } +} + /* * Opal message notifier based on message type. Allow subscribers to get * notified for specific messgae type. @@ -238,14 +288,32 @@ machine_early_initcall(powernv, opal_register_exception_handlers); int opal_message_notifier_register(enum opal_msg_type msg_type, struct notifier_block *nb) { + int ret; + unsigned long flags; + if (!nb || msg_type >= OPAL_MSG_TYPE_MAX) { pr_warn("%s: Invalid arguments, msg_type:%d\n", __func__, msg_type); return -EINVAL; } - return atomic_notifier_chain_register( - &opal_msg_notifier_head[msg_type], nb); + spin_lock_irqsave(&msg_list_lock, flags); + ret = atomic_notifier_chain_register( + &opal_msg_notifier_head[msg_type], nb); + + if (ret) { + spin_unlock_irqrestore(&msg_list_lock, flags); + return ret; + } + + /* Replay any queued messages that came in */ + /* prior to the notifier chain registration */ + /* msg_list_lock held here to assure completion */ + + dequeue_replay_msg(msg_type); + spin_unlock_irqrestore(&msg_list_lock, flags); + + return 0; } EXPORT_SYMBOL_GPL(opal_message_notifier_register); @@ -259,6 +327,23 @@ EXPORT_SYMBOL_GPL(opal_message_notifier_unregister); static void opal_message_do_notify(uint32_t msg_type, void *msg) { + unsigned long flags; + bool queued = false; + + spin_lock_irqsave(&msg_list_lock, flags); + if (opal_msg_notifier_head[msg_type].head == NULL) { + /* + * Queue up the msg since no notifiers have registered + * yet for this msg_type. + */ + queue_replay_msg(msg); + queued = true; + } + spin_unlock_irqrestore(&msg_list_lock, flags); + + if (queued) + return; + /* notify subscribers */ atomic_notifier_call_chain(&opal_msg_notifier_head[msg_type], msg_type, msg); -- 2.7.4