/* SPDX-License-Identifier: GPL-2.0-only */#ifndef _KERNEL_TIME_MIGRATION_H#define _KERNEL_TIME_MIGRATION_H /* Per group capacity. Must be a power of 2! */#define TMIGR_CHILDREN_PER_GROUP 8 /** * struct tmigr_hierarchy - a hierarchy associated to a given CPU capacity. *                          Homogeneous systems have only one hierarchy. *                          Heterogenous have one hierarchy per CPU capacity. * @cpumask:	CPUs belonging to this hierarchy * @root:	The current root of the hierarchy * @capacity:	CPU capacity associated to this hierarchy * @node:	Node in the global hierarchy list * @level_list:	Per level lists of tmigr groups */struct tmigr_hierarchy {	struct cpumask		*cpumask;	struct tmigr_group	*root;	unsigned long		capacity;	struct list_head	node;	struct list_head	level_list[];}; /** * struct tmigr_event - a timer event associated to a CPU * @nextevt:	The node to enqueue an event in the parent group queue * @cpu:	The CPU to which this event belongs * @ignore:	Hint whether the event could be ignored; it is set when *		CPU or group is active; */struct tmigr_event {	struct timerqueue_node	nextevt;	unsigned int		cpu;	bool			ignore;}; /** * struct tmigr_group - timer migration hierarchy group * @lock:		Lock protecting the event information and group hierarchy *			information during setup * @parent:		Pointer to the parent group. Pointer is updated when a *			new hierarchy level is added because of a CPU coming *			online the first time. Once it is set, the pointer will *			not be removed or updated. When accessing parent pointer *			lock less to decide whether to abort a propagation or *			not, it is not a problem. The worst outcome is an *			unnecessary/early CPU wake up. But do not access parent *			pointer several times in the same 'action' (like *			activation, deactivation, check for remote expiry,...) *			without holding the lock as it is not ensured that value *			will not change. * @groupevt:		Next event of the group which is only used when the *			group is !active. The group event is then queued into *			the parent timer queue. *			Ignore bit of @groupevt is set when the group is active. * @next_expiry:	Base monotonic expiry time of the next event of the *			group; It is used for the racy lockless check whether a *			remote expiry is required; it is always reliable * @events:		Timer queue for child events queued in the group * @migr_state:		State of the group (see union tmigr_state) * @level:		Hierarchy level of the group; Required during setup * @numa_node:		Required for setup only to make sure CPU and low level *			group information is NUMA local. It is set to NUMA node *			as long as the group level is per NUMA node (level < *			tmigr_crossnode_level); otherwise it is set to *			NUMA_NO_NODE * @num_children:	Counter of group children to make sure the group is only *			filled with TMIGR_CHILDREN_PER_GROUP; Required for setup *			only * @groupmask:		mask of the group in the parent group; is set during *			setup and will never change; can be read lockless * @list:		List head that is added to the per level *			tmigr_level_list; is required during setup when a *			new group needs to be connected to the existing *			hierarchy groups */struct tmigr_group {	raw_spinlock_t		lock;	struct tmigr_group	*parent;	struct tmigr_event	groupevt;	u64			next_expiry;	struct timerqueue_head	events;	atomic_t		migr_state;	unsigned int		level;	int			numa_node;	unsigned int		num_children;	u8			groupmask;	struct list_head	list;}; /** * struct tmigr_cpu - timer migration per CPU group * @lock:		Lock protecting the tmigr_cpu group information * @available:		Indicates whether the CPU is available for handling *			global timers. In the deactivate path it is required to *			know whether the migrator in the top level group is to *			be set offline, while a timer is pending. Then another *			available CPU needs to be notified to take over the *			migrator role. Furthermore the information is required *			in the CPU hotplug path as the CPU is able to go idle *			before the timer migration hierarchy hotplug callback is *			reached.  During this phase, the CPU has to handle the *			global timers on its own and must not act as a migrator. * * @idle:		Indicates whether the CPU is idle in the timer migration *			hierarchy * @remote:		Is set when timers of the CPU are expired remotely * @tmgroup:		Pointer to the parent group * @groupmask:		mask of tmigr_cpu in the parent group * @wakeup:		Stores the first timer when the timer migration *			hierarchy is completely idle and remote expiry was done; *			is returned to timer code in the idle path and is only *			used in idle path. * @cpuevt:		CPU event which could be enqueued into the parent group */struct tmigr_cpu {	raw_spinlock_t		lock;	bool			available;	bool			idle;	bool			remote;	struct tmigr_group	*tmgroup;	u8			groupmask;	u64			wakeup;	struct tmigr_event	cpuevt;}; /** * union tmigr_state - state of tmigr_group * @state:	Combined version of the state - only used for atomic *		read/cmpxchg function * &anon struct: Split version of the state - only use the struct members to *		update information to stay independent of endianness * @active:	Contains each mask bit of the active children * @migrator:	Contains mask of the child which is migrator * @seq:	Sequence counter needs to be increased when an update *		to the tmigr_state is done. It prevents a race when *		updates in the child groups are propagated in changed *		order. Detailed information about the scenario is *		given in the documentation at the begin of *		timer_migration.c. */union tmigr_state {	u32 state;	struct {		u8	active;		u8	migrator;		u16	seq;	} __packed;}; #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)extern void tmigr_handle_remote(void);extern bool tmigr_requires_handle_remote(void);extern void tmigr_cpu_activate(void);extern u64 tmigr_cpu_deactivate(u64 nextevt);extern u64 tmigr_cpu_new_timer(u64 nextevt);extern u64 tmigr_quick_check(u64 nextevt);#elsestatic inline void tmigr_handle_remote(void) { }static inline bool tmigr_requires_handle_remote(void) { return false; }static inline void tmigr_cpu_activate(void) { }#endif #endif