On 8/30/25 11:33 AM, Haren Myneni wrote: > The hypervisor signals the OS via a Hypervisor Pipe Event external > interrupt when data is available to be received from the pipe. > Then the OS should call RTAS check-exception and provide the input > Event Mask as defined for the ‘ibm,hvpipe-msg-events’. In response, > check-exception will return an event log containing an Pipe Events > message. This message contains the source ID for which this > message is intended to and the pipe status such as whether the > payload is pending in the hypervisor or pipe to source is closed. > > If there is any user space process waiting in the wait_queue for > the payload from this source ID, wake up that process which can > issue read() to obtain payload with ibm,receive-hvpipe-msg RTAS > or close FD if the pipe to source is closed. > > The hypervisor has one pipe per partition for all sources and it > will not deliver another hvpipe event message until the partition > reads the payload for the previous hvpipe event. So if the source > ID is not found in the source list, issue the dummy > ibm,receive-hvpipe-msg RTAS so that pipe will not blocked. > > Register hvpipe event source interrupt based on entries from > /proc/device-tree//event-sources/ibm,hvpipe-msg-events property. > > Signed-off-by: Haren Myneni <[email protected]> > Reviewed-by: Mahesh Salgaonkar <[email protected]> > Reviewed-by: Tyrel Datwyler <[email protected]> > Tested-by: Shashank MS <[email protected]> > --- > arch/powerpc/platforms/pseries/papr-hvpipe.c | 146 ++++++++++++++++++- > arch/powerpc/platforms/pseries/papr-hvpipe.h | 14 ++ > 2 files changed, 155 insertions(+), 5 deletions(-) > > diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c > b/arch/powerpc/platforms/pseries/papr-hvpipe.c > index 1e7636c0b275..0969efb39d95 100644 > --- a/arch/powerpc/platforms/pseries/papr-hvpipe.c > +++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c > @@ -22,6 +22,11 @@ > static DEFINE_SPINLOCK(hvpipe_src_list_lock); > static LIST_HEAD(hvpipe_src_list); > > +static unsigned char hvpipe_ras_buf[RTAS_ERROR_LOG_MAX]; > +static struct workqueue_struct *papr_hvpipe_wq; > +static struct work_struct *papr_hvpipe_work = NULL; > +static int hvpipe_check_exception_token; > + checkpatch.pl is not happy, reporting these errors ERROR: do not initialise statics to NULL #53: FILE: arch/powerpc/platforms/pseries/papr-hvpipe.c:27: +static struct work_struct *papr_hvpipe_work = NULL; WARNING: else is not generally useful after a break or return #205: FILE: arch/powerpc/platforms/pseries/papr-hvpipe.c:716: + return 0; + } else total: 1 errors, 1 warnings, 183 lines checked > /* > * New PowerPC FW provides support for partitions and various > * sources (Ex: remote hardware management console (HMC)) to > @@ -556,6 +561,117 @@ static long papr_hvpipe_dev_ioctl(struct file *filp, > unsigned int ioctl, > return ret; > } > > +/* > + * papr_hvpipe_work_fn - called to issue recv HVPIPE RTAS for > + * sources that are not monitored by user space so that pipe > + * will not be blocked. > + */ > +static void papr_hvpipe_work_fn(struct work_struct *work) > +{ > + hvpipe_rtas_recv_msg(NULL, 0); > +} > + > +/* > + * HVPIPE event message IRQ handler. > + * The hypervisor sends event IRQ if the partition has payload > + * and generates another event only after payload is read with > + * recv HVPIPE RTAS. > + */ > +static irqreturn_t hvpipe_event_interrupt(int irq, void *dev_id) > +{ > + struct hvpipe_event_buf *hvpipe_event; > + struct pseries_errorlog *pseries_log; > + struct hvpipe_source_info *src_info; > + struct rtas_error_log *elog; > + int rc; > + > + rc = rtas_call(hvpipe_check_exception_token, 6, 1, NULL, > + RTAS_VECTOR_EXTERNAL_INTERRUPT, virq_to_hw(irq), > + RTAS_HVPIPE_MSG_EVENTS, 1, __pa(&hvpipe_ras_buf), > + rtas_get_error_log_max()); > + > + if (rc != 0) { > + pr_err_ratelimited("unexpected hvpipe-event-notification failed > %d\n", rc); > + return IRQ_HANDLED; > + } > + > + elog = (struct rtas_error_log *)hvpipe_ras_buf; > + if (unlikely(rtas_error_type(elog) != RTAS_TYPE_HVPIPE)) { > + pr_warn_ratelimited("Unexpected event type %d\n", > + rtas_error_type(elog)); > + return IRQ_HANDLED; > + } > + > + pseries_log = get_pseries_errorlog(elog, > + PSERIES_ELOG_SECT_ID_HVPIPE_EVENT); > + hvpipe_event = (struct hvpipe_event_buf *)pseries_log->data; > + > + /* > + * The hypervisor notifies partition when the payload is > + * available to read with recv HVPIPE RTAS and it will not > + * notify another event for any source until the previous > + * payload is read. Means the pipe is blocked in the > + * hypervisor until the payload is read. > + * > + * If the source is ready to accept payload and wakeup the > + * corresponding FD. Hold lock and update hvpipe_status > + * and this lock is needed in case the user space process > + * is in release FD instead of poll() so that release() > + * reads the payload to unblock pipe before closing FD. > + * > + * otherwise (means no other user process waiting for the > + * payload, issue recv HVPIPE RTAS (papr_hvpipe_work_fn()) > + * to unblock pipe. > + */ > + spin_lock(&hvpipe_src_list_lock); > + src_info = hvpipe_find_source(be32_to_cpu(hvpipe_event->srcID)); > + if (src_info) { > + u32 flags = 0; > + > + if (hvpipe_event->event_type & HVPIPE_LOST_CONNECTION) > + flags = HVPIPE_LOST_CONNECTION; > + else if (hvpipe_event->event_type & HVPIPE_MSG_AVAILABLE) > + flags = HVPIPE_MSG_AVAILABLE; > + > + src_info->hvpipe_status |= flags; > + wake_up(&src_info->recv_wqh); > + spin_unlock(&hvpipe_src_list_lock); > + } else { > + spin_unlock(&hvpipe_src_list_lock); > + /* > + * user space is not waiting on this source. So > + * execute receive pipe RTAS so that pipe will not > + * be blocked. > + */ > + if (hvpipe_event->event_type & HVPIPE_MSG_AVAILABLE) > + queue_work(papr_hvpipe_wq, papr_hvpipe_work); > + } > + > + return IRQ_HANDLED; > +} > + > +static int __init enable_hvpipe_IRQ(void) > +{ > + struct device_node *np; > + > + hvpipe_check_exception_token = > rtas_function_token(RTAS_FN_CHECK_EXCEPTION); > + if (hvpipe_check_exception_token == RTAS_UNKNOWN_SERVICE) > + return -ENODEV; > + > + /* hvpipe events */ > + np = of_find_node_by_path("/event-sources/ibm,hvpipe-msg-events"); > + if (np != NULL) { > + request_event_sources_irqs(np, hvpipe_event_interrupt, > + "HPIPE_EVENT"); > + of_node_put(np); > + } else { > + pr_err("Can not enable hvpipe event IRQ\n"); > + return -ENODEV; > + } > + > + return 0; > +} > + > static const struct file_operations papr_hvpipe_ops = { > .unlocked_ioctl = papr_hvpipe_dev_ioctl, > }; > @@ -578,12 +694,32 @@ static int __init papr_hvpipe_init(void) > !rtas_function_implemented(RTAS_FN_IBM_RECEIVE_HVPIPE_MSG)) > return -ENODEV; > > - ret = misc_register(&papr_hvpipe_dev); > - if (ret) { > - pr_err("misc-dev registration failed %d\n", ret); > - return ret; > + papr_hvpipe_work = kzalloc(sizeof(struct work_struct), GFP_ATOMIC); > + if (!papr_hvpipe_work) > + return -ENOMEM; > + > + INIT_WORK(papr_hvpipe_work, papr_hvpipe_work_fn); > + > + papr_hvpipe_wq = alloc_ordered_workqueue("papr hvpipe workqueue", 0); > + if (!papr_hvpipe_wq) { > + ret = -ENOMEM; > + goto out; > } > > - return 0; > + ret = enable_hvpipe_IRQ(); > + if (!ret) > + ret = misc_register(&papr_hvpipe_dev); > + > + if (!ret) { > + pr_info("hvpipe feature is enabled\n"); > + return 0; > + } else > + pr_err("hvpipe feature is not enabled %d\n", ret); > + > + destroy_workqueue(papr_hvpipe_wq); > +out: > + kfree(papr_hvpipe_work); > + papr_hvpipe_work = NULL; > + return ret; > } > machine_device_initcall(pseries, papr_hvpipe_init); > diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.h > b/arch/powerpc/platforms/pseries/papr-hvpipe.h > index 125658e6b596..aab7f77e087d 100644 > --- a/arch/powerpc/platforms/pseries/papr-hvpipe.h > +++ b/arch/powerpc/platforms/pseries/papr-hvpipe.h > @@ -19,4 +19,18 @@ struct hvpipe_source_info { > struct task_struct *tsk; > }; > > +/* > + * Source ID Format 0xCCRRQQQQ > + * CC = indicating value is source type (ex: 0x02 for HMC) > + * RR = 0x00 (reserved) > + * QQQQ = 0x0000 – 0xFFFF indicating the source index indetifier > + */ > +struct hvpipe_event_buf { > + __be32 srcID; /* Source ID */ > + u8 event_type; /* 0x01 for hvpipe message available */ > + /* from specified src ID */ > + /* 0x02 for loss of pipe connection */ > + /* with specified src ID */ > +}; > + > #endif /* _PAPR_HVPIPE_H */
