Hotplug events are critical indicators for analyzing hardware health, and surprise link downs can significantly impact system performance and reliability.
Define a new TRACING_SYSTEM named "pci", add a generic RAS tracepoint for hotplug event to help health checks. Add enum pci_hotplug_event in include/uapi/linux/pci.h so applications like rasdaemon can register tracepoint event handlers for it. The following output is generated when a device is hotplugged: $ echo 1 > /sys/kernel/debug/tracing/events/pci/pci_hp_event/enable $ cat /sys/kernel/debug/tracing/trace_pipe irq/51-pciehp-88 [001] ..... 1311.177459: pci_hp_event: 0000:00:02.0 slot:10, event:CARD_PRESENT irq/51-pciehp-88 [001] ..... 1311.177566: pci_hp_event: 0000:00:02.0 slot:10, event:LINK_UP Suggested-by: Lukas Wunner <[email protected]> Reviewed-by: Lukas Wunner <[email protected]> Reviewed-by: Jonathan Cameron <[email protected]> Reviewed-by: "Steven Rostedt (Google)" <[email protected]> # for trace event Reviewed-by: Ilpo Järvinen <[email protected]> Signed-off-by: Shuai Xue <[email protected]> --- drivers/pci/Makefile | 3 ++ drivers/pci/hotplug/pciehp_ctrl.c | 31 ++++++++++--- drivers/pci/trace.c | 11 +++++ include/trace/events/pci.h | 72 +++++++++++++++++++++++++++++++ include/uapi/linux/pci.h | 7 +++ 5 files changed, 118 insertions(+), 6 deletions(-) create mode 100644 drivers/pci/trace.c create mode 100644 include/trace/events/pci.h diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile index 67647f1880fb..58a4e4ea76b0 100644 --- a/drivers/pci/Makefile +++ b/drivers/pci/Makefile @@ -45,3 +45,6 @@ obj-y += controller/ obj-y += switch/ subdir-ccflags-$(CONFIG_PCI_DEBUG) := -DDEBUG + +CFLAGS_trace.o := -I$(src) +obj-$(CONFIG_TRACING) += trace.o diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c index bcc938d4420f..7805f697a02c 100644 --- a/drivers/pci/hotplug/pciehp_ctrl.c +++ b/drivers/pci/hotplug/pciehp_ctrl.c @@ -19,6 +19,7 @@ #include <linux/types.h> #include <linux/pm_runtime.h> #include <linux/pci.h> +#include <trace/events/pci.h> #include "../pci.h" #include "pciehp.h" @@ -244,12 +245,20 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) case ON_STATE: ctrl->state = POWEROFF_STATE; mutex_unlock(&ctrl->state_lock); - if (events & PCI_EXP_SLTSTA_DLLSC) + if (events & PCI_EXP_SLTSTA_DLLSC) { ctrl_info(ctrl, "Slot(%s): Link Down\n", slot_name(ctrl)); - if (events & PCI_EXP_SLTSTA_PDC) + trace_pci_hp_event(pci_name(ctrl->pcie->port), + slot_name(ctrl), + PCI_HOTPLUG_LINK_DOWN); + } + if (events & PCI_EXP_SLTSTA_PDC) { ctrl_info(ctrl, "Slot(%s): Card not present\n", slot_name(ctrl)); + trace_pci_hp_event(pci_name(ctrl->pcie->port), + slot_name(ctrl), + PCI_HOTPLUG_CARD_NOT_PRESENT); + } pciehp_disable_slot(ctrl, SURPRISE_REMOVAL); break; default: @@ -269,6 +278,9 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) INDICATOR_NOOP); ctrl_info(ctrl, "Slot(%s): Card not present\n", slot_name(ctrl)); + trace_pci_hp_event(pci_name(ctrl->pcie->port), + slot_name(ctrl), + PCI_HOTPLUG_CARD_NOT_PRESENT); } mutex_unlock(&ctrl->state_lock); return; @@ -281,12 +293,19 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) case OFF_STATE: ctrl->state = POWERON_STATE; mutex_unlock(&ctrl->state_lock); - if (present) + if (present) { ctrl_info(ctrl, "Slot(%s): Card present\n", slot_name(ctrl)); - if (link_active) - ctrl_info(ctrl, "Slot(%s): Link Up\n", - slot_name(ctrl)); + trace_pci_hp_event(pci_name(ctrl->pcie->port), + slot_name(ctrl), + PCI_HOTPLUG_CARD_PRESENT); + } + if (link_active) { + ctrl_info(ctrl, "Slot(%s): Link Up\n", slot_name(ctrl)); + trace_pci_hp_event(pci_name(ctrl->pcie->port), + slot_name(ctrl), + PCI_HOTPLUG_LINK_UP); + } ctrl->request_result = pciehp_enable_slot(ctrl); break; default: diff --git a/drivers/pci/trace.c b/drivers/pci/trace.c new file mode 100644 index 000000000000..cf11abca8602 --- /dev/null +++ b/drivers/pci/trace.c @@ -0,0 +1,11 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Tracepoints for PCI system + * + * Copyright (C) 2025 Alibaba Corporation + */ + +#include <linux/pci.h> + +#define CREATE_TRACE_POINTS +#include <trace/events/pci.h> diff --git a/include/trace/events/pci.h b/include/trace/events/pci.h new file mode 100644 index 000000000000..39e512a167ee --- /dev/null +++ b/include/trace/events/pci.h @@ -0,0 +1,72 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM pci + +#if !defined(_TRACE_HW_EVENT_PCI_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_HW_EVENT_PCI_H + +#include <linux/tracepoint.h> + +#define PCI_HOTPLUG_EVENT \ + EM(PCI_HOTPLUG_LINK_UP, "LINK_UP") \ + EM(PCI_HOTPLUG_LINK_DOWN, "LINK_DOWN") \ + EM(PCI_HOTPLUG_CARD_PRESENT, "CARD_PRESENT") \ + EMe(PCI_HOTPLUG_CARD_NOT_PRESENT, "CARD_NOT_PRESENT") + +/* Enums require being exported to userspace, for user tool parsing */ +#undef EM +#undef EMe +#define EM(a, b) TRACE_DEFINE_ENUM(a); +#define EMe(a, b) TRACE_DEFINE_ENUM(a); + +PCI_HOTPLUG_EVENT + +/* + * Now redefine the EM() and EMe() macros to map the enums to the strings + * that will be printed in the output. + */ +#undef EM +#undef EMe +#define EM(a, b) {a, b}, +#define EMe(a, b) {a, b} + +/* + * Note: For generic PCI hotplug events, we pass already-resolved strings + * (port_name, slot) instead of driver-specific structures like 'struct + * controller'. This is because different PCI hotplug drivers (pciehp, cpqphp, + * ibmphp, shpchp) define their own versions of 'struct controller' with + * different fields and helper functions. Using driver-specific structures would + * make the tracepoint interface non-generic and cause compatibility issues + * across different drivers. + */ +TRACE_EVENT(pci_hp_event, + + TP_PROTO(const char *port_name, + const char *slot, + const int event), + + TP_ARGS(port_name, slot, event), + + TP_STRUCT__entry( + __string( port_name, port_name ) + __string( slot, slot ) + __field( int, event ) + ), + + TP_fast_assign( + __assign_str(port_name); + __assign_str(slot); + __entry->event = event; + ), + + TP_printk("%s slot:%s, event:%s\n", + __get_str(port_name), + __get_str(slot), + __print_symbolic(__entry->event, PCI_HOTPLUG_EVENT) + ) +); + +#endif /* _TRACE_HW_EVENT_PCI_H */ + +/* This part must be outside protection */ +#include <trace/define_trace.h> diff --git a/include/uapi/linux/pci.h b/include/uapi/linux/pci.h index a769eefc5139..4f150028965d 100644 --- a/include/uapi/linux/pci.h +++ b/include/uapi/linux/pci.h @@ -39,4 +39,11 @@ #define PCIIOC_MMAP_IS_MEM (PCIIOC_BASE | 0x02) /* Set mmap state to MEM space. */ #define PCIIOC_WRITE_COMBINE (PCIIOC_BASE | 0x03) /* Enable/disable write-combining. */ +enum pci_hotplug_event { + PCI_HOTPLUG_LINK_UP, + PCI_HOTPLUG_LINK_DOWN, + PCI_HOTPLUG_CARD_PRESENT, + PCI_HOTPLUG_CARD_NOT_PRESENT, +}; + #endif /* _UAPILINUX_PCI_H */ -- 2.39.3
