x86: kvm: Revert "remove sched notifier for cross-cpu migrations" (0a4e6be9) · Commits · 戴 / test

arch/x86/include/asm/pvclock.h

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -95,6 +95,7 @@ unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,

	struct pvclock_vsyscall_time_info {		struct pvclock_vsyscall_time_info {
	struct pvclock_vcpu_time_info pvti;		struct pvclock_vcpu_time_info pvti;
			u32 migrate_count;
	} __attribute__((__aligned__(SMP_CACHE_BYTES)));		} __attribute__((__aligned__(SMP_CACHE_BYTES)));

	#define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)		#define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)

arch/x86/kernel/pvclock.c

+44 −0

Original line number	Original line	Diff line number	Diff line
	@@ -141,7 +141,46 @@ void pvclock_read_wallclock(struct pvclock_wall_clock *wall_clock,
	set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);		set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
	}		}

			static struct pvclock_vsyscall_time_info *pvclock_vdso_info;

			static struct pvclock_vsyscall_time_info *
			pvclock_get_vsyscall_user_time_info(int cpu)
			{
			if (!pvclock_vdso_info) {
			BUG();
			return NULL;
			}

			return &pvclock_vdso_info[cpu];
			}

			struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu)
			{
			return &pvclock_get_vsyscall_user_time_info(cpu)->pvti;
			}

	#ifdef CONFIG_X86_64		#ifdef CONFIG_X86_64
			static int pvclock_task_migrate(struct notifier_block *nb, unsigned long l,
			void *v)
			{
			struct task_migration_notifier *mn = v;
			struct pvclock_vsyscall_time_info *pvti;

			pvti = pvclock_get_vsyscall_user_time_info(mn->from_cpu);

			/* this is NULL when pvclock vsyscall is not initialized */
			if (unlikely(pvti == NULL))
			return NOTIFY_DONE;

			pvti->migrate_count++;

			return NOTIFY_DONE;
			}

			static struct notifier_block pvclock_migrate = {
			.notifier_call = pvclock_task_migrate,
			};

	/*		/*
	* Initialize the generic pvclock vsyscall state. This will allocate		* Initialize the generic pvclock vsyscall state. This will allocate
	* a/some page(s) for the per-vcpu pvclock information, set up a		* a/some page(s) for the per-vcpu pvclock information, set up a
	@@ -155,12 +194,17 @@ int __init pvclock_init_vsyscall(struct pvclock_vsyscall_time_info *i,

	WARN_ON (size != PVCLOCK_VSYSCALL_NR_PAGES*PAGE_SIZE);		WARN_ON (size != PVCLOCK_VSYSCALL_NR_PAGES*PAGE_SIZE);

			pvclock_vdso_info = i;

	for (idx = 0; idx <= (PVCLOCK_FIXMAP_END-PVCLOCK_FIXMAP_BEGIN); idx++) {		for (idx = 0; idx <= (PVCLOCK_FIXMAP_END-PVCLOCK_FIXMAP_BEGIN); idx++) {
	__set_fixmap(PVCLOCK_FIXMAP_BEGIN + idx,		__set_fixmap(PVCLOCK_FIXMAP_BEGIN + idx,
	__pa(i) + (idx*PAGE_SIZE),		__pa(i) + (idx*PAGE_SIZE),
	PAGE_KERNEL_VVAR);		PAGE_KERNEL_VVAR);
	}		}


			register_task_migration_notifier(&pvclock_migrate);

	return 0;		return 0;
	}		}
	#endif		#endif

arch/x86/vdso/vclock_gettime.c

+8 −8

Original line number	Original line	Diff line number	Diff line
	@@ -82,18 +82,15 @@ static notrace cycle_t vread_pvclock(int *mode)
	cycle_t ret;		cycle_t ret;
	u64 last;		u64 last;
	u32 version;		u32 version;
			u32 migrate_count;
	u8 flags;		u8 flags;
	unsigned cpu, cpu1;		unsigned cpu, cpu1;


	/*		/*
	* Note: hypervisor must guarantee that:		* When looping to get a consistent (time-info, tsc) pair, we
	* 1. cpu ID number maps 1:1 to per-CPU pvclock time info.		* also need to deal with the possibility we can switch vcpus,
	* 2. that per-CPU pvclock time info is updated if the		* so make sure we always re-fetch time-info for the current vcpu.
	* underlying CPU changes.
	* 3. that version is increased whenever underlying CPU
	* changes.
	*
	*/		*/
	do {		do {
	cpu = __getcpu() & VGETCPU_CPU_MASK;		cpu = __getcpu() & VGETCPU_CPU_MASK;
	@@ -104,6 +101,8 @@ static notrace cycle_t vread_pvclock(int *mode)

	pvti = get_pvti(cpu);		pvti = get_pvti(cpu);

			migrate_count = pvti->migrate_count;

	version = __pvclock_read_cycles(&pvti->pvti, &ret, &flags);		version = __pvclock_read_cycles(&pvti->pvti, &ret, &flags);

	/*		/*
	@@ -115,7 +114,8 @@ static notrace cycle_t vread_pvclock(int *mode)
	cpu1 = __getcpu() & VGETCPU_CPU_MASK;		cpu1 = __getcpu() & VGETCPU_CPU_MASK;
	} while (unlikely(cpu != cpu1 \|\|		} while (unlikely(cpu != cpu1 \|\|
	(pvti->pvti.version & 1) \|\|		(pvti->pvti.version & 1) \|\|
	pvti->pvti.version != version));		pvti->pvti.version != version \|\|
			pvti->migrate_count != migrate_count));

	if (unlikely(!(flags & PVCLOCK_TSC_STABLE_BIT)))		if (unlikely(!(flags & PVCLOCK_TSC_STABLE_BIT)))
	*mode = VCLOCK_NONE;		*mode = VCLOCK_NONE;

include/linux/sched.h

+8 −0

Original line number	Original line	Diff line number	Diff line
	@@ -176,6 +176,14 @@ extern void get_iowait_load(unsigned long nr_waiters, unsigned long load);
	extern void calc_global_load(unsigned long ticks);		extern void calc_global_load(unsigned long ticks);
	extern void update_cpu_load_nohz(void);		extern void update_cpu_load_nohz(void);

			/* Notifier for when a task gets migrated to a new CPU */
			struct task_migration_notifier {
			struct task_struct *task;
			int from_cpu;
			int to_cpu;
			};
			extern void register_task_migration_notifier(struct notifier_block *n);

	extern unsigned long get_parent_ip(unsigned long addr);		extern unsigned long get_parent_ip(unsigned long addr);

	extern void dump_cpu_task(int cpu);		extern void dump_cpu_task(int cpu);

kernel/sched/core.c

+15 −0

Original line number	Original line	Diff line number	Diff line
	@@ -996,6 +996,13 @@ void check_preempt_curr(struct rq rq, struct task_struct p, int flags)
	rq_clock_skip_update(rq, true);		rq_clock_skip_update(rq, true);
	}		}

			static ATOMIC_NOTIFIER_HEAD(task_migration_notifier);

			void register_task_migration_notifier(struct notifier_block *n)
			{
			atomic_notifier_chain_register(&task_migration_notifier, n);
			}

	#ifdef CONFIG_SMP		#ifdef CONFIG_SMP
	void set_task_cpu(struct task_struct *p, unsigned int new_cpu)		void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
	{		{
	@@ -1026,10 +1033,18 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
	trace_sched_migrate_task(p, new_cpu);		trace_sched_migrate_task(p, new_cpu);

	if (task_cpu(p) != new_cpu) {		if (task_cpu(p) != new_cpu) {
			struct task_migration_notifier tmn;

	if (p->sched_class->migrate_task_rq)		if (p->sched_class->migrate_task_rq)
	p->sched_class->migrate_task_rq(p, new_cpu);		p->sched_class->migrate_task_rq(p, new_cpu);
	p->se.nr_migrations++;		p->se.nr_migrations++;
	perf_sw_event_sched(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 0);		perf_sw_event_sched(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 0);

			tmn.task = p;
			tmn.from_cpu = task_cpu(p);
			tmn.to_cpu = new_cpu;

			atomic_notifier_call_chain(&task_migration_notifier, 0, &tmn);
	}		}

	__set_task_cpu(p, new_cpu);		__set_task_cpu(p, new_cpu);

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