Release 4.7 arch/x86/kernel/kvm.c

/*
 * KVM paravirt_ops implementation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 * Copyright IBM Corporation, 2007
 *   Authors: Anthony Liguori <aliguori@us.ibm.com>
 */

#include <linux/context_tracking.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/kvm_para.h>
#include <linux/cpu.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/hardirq.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/hash.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kprobes.h>
#include <linux/debugfs.h>
#include <linux/nmi.h>
#include <linux/swait.h>
#include <asm/timer.h>
#include <asm/cpu.h>
#include <asm/traps.h>
#include <asm/desc.h>
#include <asm/tlbflush.h>
#include <asm/idle.h>
#include <asm/apic.h>
#include <asm/apicdef.h>
#include <asm/hypervisor.h>
#include <asm/kvm_guest.h>


static int kvmapf = 1;



static int parse_no_kvmapf(char *arg)
{
        kvmapf = 0;
        return 0;
}

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early_param("no-kvmapf", parse_no_kvmapf);


static int steal_acc = 1;


static int parse_no_stealacc(char *arg)
{
        steal_acc = 0;
        return 0;
}

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early_param("no-steal-acc", parse_no_stealacc);


static int kvmclock_vsyscall = 1;


static int parse_no_kvmclock_vsyscall(char *arg)
{
        kvmclock_vsyscall = 0;
        return 0;
}

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early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall);

static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);

static int has_steal_clock = 0;

/*
 * No need for any "IO delay" on KVM
 */


static void kvm_io_delay(void)
{
}

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#define KVM_TASK_SLEEP_HASHBITS 8

#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)


struct kvm_task_sleep_node {
	
struct hlist_node link;
	
struct swait_queue_head wq;
	
u32 token;
	
int cpu;
	
bool halted;
};


static struct kvm_task_sleep_head {
	
raw_spinlock_t lock;
	
struct hlist_head list;
} 
async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];



static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
						  u32 token)
{
	struct hlist_node *p;

	hlist_for_each(p, &b->list) {
		struct kvm_task_sleep_node *n =
			hlist_entry(p, typeof(*n), link);
		if (n->token == token)
			return n;
	}

	return NULL;
}

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void kvm_async_pf_task_wait(u32 token)
{
	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
	struct kvm_task_sleep_node n, *e;
	DECLARE_SWAITQUEUE(wait);

	rcu_irq_enter();

	raw_spin_lock(&b->lock);
	e = _find_apf_task(b, token);
	if (e) {
		/* dummy entry exist -> wake up was delivered ahead of PF */
		hlist_del(&e->link);
		kfree(e);
		raw_spin_unlock(&b->lock);

		rcu_irq_exit();
		return;
	}

	n.token = token;
	n.cpu = smp_processor_id();
	n.halted = is_idle_task(current) || preempt_count() > 1;
	init_swait_queue_head(&n.wq);
	hlist_add_head(&n.link, &b->list);
	raw_spin_unlock(&b->lock);

	for (;;) {
		if (!n.halted)
			prepare_to_swait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
		if (hlist_unhashed(&n.link))
			break;

		if (!n.halted) {
			local_irq_enable();
			schedule();
			local_irq_disable();
		} else {
			/*
                         * We cannot reschedule. So halt.
                         */
			rcu_irq_exit();
			native_safe_halt();
			rcu_irq_enter();
			local_irq_disable();
		}
	}
	if (!n.halted)
		finish_swait(&n.wq, &wait);

	rcu_irq_exit();
	return;
}
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EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);



static void apf_task_wake_one(struct kvm_task_sleep_node *n)
{
	hlist_del_init(&n->link);
	if (n->halted)
		smp_send_reschedule(n->cpu);
	else if (swait_active(&n->wq))
		swake_up(&n->wq);
}

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static void apf_task_wake_all(void)
{
	int i;

	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
		struct hlist_node *p, *next;
		struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
		raw_spin_lock(&b->lock);
		hlist_for_each_safe(p, next, &b->list) {
			struct kvm_task_sleep_node *n =
				hlist_entry(p, typeof(*n), link);
			if (n->cpu == smp_processor_id())
				apf_task_wake_one(n);
		}
		raw_spin_unlock(&b->lock);
	}
}

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void kvm_async_pf_task_wake(u32 token)
{
	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
	struct kvm_task_sleep_node *n;

	if (token == ~0) {
		apf_task_wake_all();
		return;
	}

again:
	raw_spin_lock(&b->lock);
	n = _find_apf_task(b, token);
	if (!n) {
		/*
                 * async PF was not yet handled.
                 * Add dummy entry for the token.
                 */
		n = kzalloc(sizeof(*n), GFP_ATOMIC);
		if (!n) {
			/*
                         * Allocation failed! Busy wait while other cpu
                         * handles async PF.
                         */
			raw_spin_unlock(&b->lock);
			cpu_relax();
			goto again;
		}
		n->token = token;
		n->cpu = smp_processor_id();
		init_swait_queue_head(&n->wq);
		hlist_add_head(&n->link, &b->list);
	} else
		apf_task_wake_one(n);
	raw_spin_unlock(&b->lock);
	return;
}
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EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);



u32 kvm_read_and_reset_pf_reason(void)
{
	u32 reason = 0;

	if (__this_cpu_read(apf_reason.enabled)) {
		reason = __this_cpu_read(apf_reason.reason);
		__this_cpu_write(apf_reason.reason, 0);
	}

	return reason;
}
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EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);

NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason);


dotraplinkage void

do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
{
	enum ctx_state prev_state;

	switch (kvm_read_and_reset_pf_reason()) {
	default:
		trace_do_page_fault(regs, error_code);
		break;
	case KVM_PV_REASON_PAGE_NOT_PRESENT:
		/* page is swapped out by the host. */
		prev_state = exception_enter();
		exit_idle();
		kvm_async_pf_task_wait((u32)read_cr2());
		exception_exit(prev_state);
		break;
	case KVM_PV_REASON_PAGE_READY:
		rcu_irq_enter();
		exit_idle();
		kvm_async_pf_task_wake((u32)read_cr2());
		rcu_irq_exit();
		break;
	}
}
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NOKPROBE_SYMBOL(do_async_page_fault);



static void __init paravirt_ops_setup(void)
{
	pv_info.name = "KVM";

	if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
		pv_cpu_ops.io_delay = kvm_io_delay;

#ifdef CONFIG_X86_IO_APIC
	no_timer_check = 1;
#endif
}

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static void kvm_register_steal_time(void)
{
	int cpu = smp_processor_id();
	struct kvm_steal_time *st = &per_cpu(steal_time, cpu);

	if (!has_steal_clock)
		return;

	memset(st, 0, sizeof(*st));

	wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
	pr_info("kvm-stealtime: cpu %d, msr %llx\n",
		cpu, (unsigned long long) slow_virt_to_phys(st));
}

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static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;



static void kvm_guest_apic_eoi_write(u32 reg, u32 val)
{
	/**
         * This relies on __test_and_clear_bit to modify the memory
         * in a way that is atomic with respect to the local CPU.
         * The hypervisor only accesses this memory from the local CPU so
         * there's no need for lock or memory barriers.
         * An optimization barrier is implied in apic write.
         */
	if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
		return;
	apic_write(APIC_EOI, APIC_EOI_ACK);
}

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static void kvm_guest_cpu_init(void)
{
	if (!kvm_para_available())
		return;

	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
		u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));

#ifdef CONFIG_PREEMPT
		pa |= KVM_ASYNC_PF_SEND_ALWAYS;
#endif
		wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED);
		__this_cpu_write(apf_reason.enabled, 1);
		printk(KERN_INFO"KVM setup async PF for cpu %d\n",
		       smp_processor_id());
	}

	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
		unsigned long pa;
		/* Size alignment is implied but just to make it explicit. */
		BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
		__this_cpu_write(kvm_apic_eoi, 0);
		pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
			| KVM_MSR_ENABLED;
		wrmsrl(MSR_KVM_PV_EOI_EN, pa);
	}

	if (has_steal_clock)
		kvm_register_steal_time();
}

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static void kvm_pv_disable_apf(void)
{
	if (!__this_cpu_read(apf_reason.enabled))
		return;

	wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
	__this_cpu_write(apf_reason.enabled, 0);

	printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
	       smp_processor_id());
}

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static void kvm_pv_guest_cpu_reboot(void *unused)
{
	/*
         * We disable PV EOI before we load a new kernel by kexec,
         * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
         * New kernel can re-enable when it boots.
         */
	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
		wrmsrl(MSR_KVM_PV_EOI_EN, 0);
	kvm_pv_disable_apf();
	kvm_disable_steal_time();
}

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static int kvm_pv_reboot_notify(struct notifier_block *nb,
				unsigned long code, void *unused)
{
	if (code == SYS_RESTART)
		on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
	return NOTIFY_DONE;
}

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static struct notifier_block kvm_pv_reboot_nb = {
	.notifier_call = kvm_pv_reboot_notify,
};



static u64 kvm_steal_clock(int cpu)
{
	u64 steal;
	struct kvm_steal_time *src;
	int version;

	src = &per_cpu(steal_time, cpu);
	do {
		version = src->version;
		rmb();
		steal = src->steal;
		rmb();
	} while ((version & 1) || (version != src->version));

	return steal;
}

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void kvm_disable_steal_time(void)
{
	if (!has_steal_clock)
		return;

	wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
}

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#ifdef CONFIG_SMP


static void __init kvm_smp_prepare_boot_cpu(void)
{
	kvm_guest_cpu_init();
	native_smp_prepare_boot_cpu();
	kvm_spinlock_init();
}

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static void kvm_guest_cpu_online(void *dummy)
{
	kvm_guest_cpu_init();
}

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static void kvm_guest_cpu_offline(void *dummy)
{
	kvm_disable_steal_time();
	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
		wrmsrl(MSR_KVM_PV_EOI_EN, 0);
	kvm_pv_disable_apf();
	apf_task_wake_all();
}

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static int kvm_cpu_notify(struct notifier_block *self, unsigned long action,
			  void *hcpu)
{
	int cpu = (unsigned long)hcpu;
	switch (action) {
	case CPU_ONLINE:
	case CPU_DOWN_FAILED:
	case CPU_ONLINE_FROZEN:
		smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0);
		break;
	case CPU_DOWN_PREPARE:
	case CPU_DOWN_PREPARE_FROZEN:
		smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1);
		break;
	default:
		break;
	}
	return NOTIFY_OK;
}

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static struct notifier_block kvm_cpu_notifier = {
        .notifier_call  = kvm_cpu_notify,
};
#endif



static void __init kvm_apf_trap_init(void)
{
	set_intr_gate(14, async_page_fault);
}

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void __init kvm_guest_init(void)
{
	int i;

	if (!kvm_para_available())
		return;

	paravirt_ops_setup();
	register_reboot_notifier(&kvm_pv_reboot_nb);
	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
		raw_spin_lock_init(&async_pf_sleepers[i].lock);
	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
		x86_init.irqs.trap_init = kvm_apf_trap_init;

	if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
		has_steal_clock = 1;
		pv_time_ops.steal_clock = kvm_steal_clock;
	}

	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
		apic_set_eoi_write(kvm_guest_apic_eoi_write);

	if (kvmclock_vsyscall)
		kvm_setup_vsyscall_timeinfo();

#ifdef CONFIG_SMP
	smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
	register_cpu_notifier(&kvm_cpu_notifier);
#else
	kvm_guest_cpu_init();
#endif

	/*
         * Hard lockup detection is enabled by default. Disable it, as guests
         * can get false positives too easily, for example if the host is
         * overcommitted.
         */
	hardlockup_detector_disable();
}

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gleb natapov
gleb natapov
69
53.08%
3
27.27%
marcelo tosatti
marcelo tosatti
25
19.23%
2
18.18%
glauber costa
glauber costa
19
14.62%
1
9.09%
michael s. tsirkin
michael s. tsirkin
12
9.23%
2
18.18%
ulrich obergfell
ulrich obergfell
4
3.08%
2
18.18%
rik van riel
rik van riel
1
0.77%
1
9.09%
Total
130
100.00%
11
100.00%



static noinline uint32_t __kvm_cpuid_base(void)
{
	if (boot_cpu_data.cpuid_level < 0)
		return 0;	/* So we don't blow up on old processors */

	if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
		return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);

	return 0;
}

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paolo bonzini
paolo bonzini
35
89.74%
1
50.00%
borislav petkov
borislav petkov
4
10.26%
1
50.00%
Total
39
100.00%
2
100.00%



static inline uint32_t kvm_cpuid_base(void)
{
	static int kvm_cpuid_base = -1;

	if (kvm_cpuid_base == -1)
		kvm_cpuid_base = __kvm_cpuid_base();

	return kvm_cpuid_base;
}

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paolo bonzini
paolo bonzini
31
100.00%
1
100.00%
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31
100.00%
1
100.00%



bool kvm_para_available(void)
{
	return kvm_cpuid_base() != 0;
}
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paolo bonzini
paolo bonzini
13
100.00%
1
100.00%
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13
100.00%
1
100.00%


EXPORT_SYMBOL_GPL(kvm_para_available);



unsigned int kvm_arch_para_features(void)
{
	return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
}

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paolo bonzini
paolo bonzini
17
100.00%
1
100.00%
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17
100.00%
1
100.00%



static uint32_t __init kvm_detect(void)
{
	return kvm_cpuid_base();
}

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prarit bhargava
prarit bhargava
10
76.92%
1
50.00%
jason wang
jason wang
3
23.08%
1
50.00%
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13
100.00%
2
100.00%


const struct hypervisor_x86 x86_hyper_kvm __refconst = {
	.name			= "KVM",
	.detect			= kvm_detect,
	.x2apic_available	= kvm_para_available,
};

EXPORT_SYMBOL_GPL(x86_hyper_kvm);



static __init int activate_jump_labels(void)
{
	if (has_steal_clock) {
		static_key_slow_inc(&paravirt_steal_enabled);
		if (steal_acc)
			static_key_slow_inc(&paravirt_steal_rq_enabled);
	}

	return 0;
}
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glauber costa
glauber costa
32
94.12%
1
50.00%
ingo molnar
ingo molnar
2
5.88%
1
50.00%
Total
34
100.00%
2
100.00%


arch_initcall(activate_jump_labels);

#ifdef CONFIG_PARAVIRT_SPINLOCKS

/* Kick a cpu by its apicid. Used to wake up a halted vcpu */


static void kvm_kick_cpu(int cpu)
{
	int apicid;
	unsigned long flags = 0;

	apicid = per_cpu(x86_cpu_to_apicid, cpu);
	kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
}


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srivatsa vaddagiri
srivatsa vaddagiri
35
97.22%
1
50.00%
raghavendra k t* (same as raghavendra koushik)
raghavendra k t* (same as raghavendra koushik)
1
2.78%
1
50.00%
Total
36
100.00%
2
100.00%

#ifdef CONFIG_QUEUED_SPINLOCKS

#include <asm/qspinlock.h>



static void kvm_wait(u8 *ptr, u8 val)
{
	unsigned long flags;

	if (in_nmi())
		return;

	local_irq_save(flags);

	if (READ_ONCE(*ptr) != val)
		goto out;

	/*
         * halt until it's our turn and kicked. Note that we do safe halt
         * for irq enabled case to avoid hang when lock info is overwritten
         * in irq spinlock slowpath and no spurious interrupt occur to save us.
         */
	if (arch_irqs_disabled_flags(flags))
		halt();
	else
		safe_halt();

out:
	local_irq_restore(flags);
}

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waiman long
waiman long
63
100.00%
1
100.00%
Total
63
100.00%
1
100.00%

#else /* !CONFIG_QUEUED_SPINLOCKS */


enum kvm_contention_stat {
	
TAKEN_SLOW,
	
TAKEN_SLOW_PICKUP,
	
RELEASED_SLOW,
	
RELEASED_SLOW_KICKED,
	
NR_CONTENTION_STATS
};

#ifdef CONFIG_KVM_DEBUG_FS

#define HISTO_BUCKETS	30


static struct kvm_spinlock_stats
{
	
u32 contention_stats[NR_CONTENTION_STATS];
	
u32 histo_spin_blocked[HISTO_BUCKETS+1];
	
u64 time_blocked;
} 
spinlock_stats;


static u8 zero_stats;



static inline void check_zero(void)
{
	u8 ret;
	u8 old;

	old = READ_ONCE(zero_stats);
	if (unlikely(old)) {
		ret = cmpxchg(&zero_stats, old, 0);
		/* This ensures only one fellow resets the stat */
		if (ret == old)
			memset(&spinlock_stats, 0, sizeof(spinlock_stats));
	}
}

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srivatsa vaddagiri
srivatsa vaddagiri
62
98.41%
1
50.00%
raghavendra k t* (same as raghavendra koushik)
raghavendra k t* (same as raghavendra koushik)
1
1.59%
1
50.00%
Total
63
100.00%
2
100.00%



static inline void add_stats(enum kvm_contention_stat var, u32 val)
{
	check_zero();
	spinlock_stats.contention_stats[var] += val;
}


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srivatsa vaddagiri
srivatsa vaddagiri
26
100.00%
1
100.00%
Total
26
100.00%
1
100.00%



static inline u64 spin_time_start(void)
{
	return sched_clock();
}

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srivatsa vaddagiri
srivatsa vaddagiri
13
100.00%
1
100.00%
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13
100.00%
1
100.00%



static void __spin_time_accum(u64 delta, u32 *array)
{
	unsigned index;

	index = ilog2(delta);
	check_zero();

	if (index < HISTO_BUCKETS)
		array[index]++;
	else
		array[HISTO_BUCKETS]++;
}

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srivatsa vaddagiri
srivatsa vaddagiri
45
100.00%
1
100.00%
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45
100.00%
1
100.00%



static inline void spin_time_accum_blocked(u64 start)
{
	u32 delta;

	delta = sched_clock() - start;
	__spin_time_accum(delta, spinlock_stats.histo_spin_blocked);
	spinlock_stats.time_blocked += delta;
}

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srivatsa vaddagiri
srivatsa vaddagiri
35
100.00%
1
100.00%
Total
35
100.00%
1
100.00%


static struct dentry *d_spin_debug;

static struct dentry *d_kvm_debug;



static struct dentry *kvm_init_debugfs(void)
{
	d_kvm_debug = debugfs_create_dir("kvm-guest", NULL);
	if (!d_kvm_debug)
		printk(KERN_WARNING "Could not create 'kvm' debugfs directory\n");

	return d_kvm_debug;
}

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srivatsa vaddagiri
srivatsa vaddagiri
31
93.94%
1
33.33%
tim gardner
tim gardner
1
3.03%
1
33.33%
nicholas krause
nicholas krause
1
3.03%
1
33.33%
Total
33
100.00%
3
100.00%



static int __init kvm_spinlock_debugfs(void)
{
	struct dentry *d_kvm;

	d_kvm = kvm_init_debugfs();
	if (d_kvm == NULL)
		return -ENOMEM;

	d_spin_debug = debugfs_create_dir("spinlocks", d_kvm);

	debugfs_create_u8("zero_stats", 0644, d_spin_debug, &zero_stats);

	debugfs_create_u32("taken_slow", 0444, d_spin_debug,
		   &spinlock_stats.contention_stats[TAKEN_SLOW]);
	debugfs_create_u32("taken_slow_pickup", 0444, d_spin_debug,
		   &spinlock_stats.contention_stats[TAKEN_SLOW_PICKUP]);

	debugfs_create_u32("released_slow", 0444, d_spin_debug,
		   &spinlock_stats.contention_stats[RELEASED_SLOW]);
	debugfs_create_u32("released_slow_kicked", 0444, d_spin_debug,
		   &spinlock_stats.contention_stats[RELEASED_SLOW_KICKED]);

	debugfs_create_u64("time_blocked", 0444, d_spin_debug,
			   &spinlock_stats.time_blocked);

	debugfs_create_u32_array("histo_blocked", 0444, d_spin_debug,
		     spinlock_stats.histo_spin_blocked, HISTO_BUCKETS + 1);

	return 0;
}
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srivatsa vaddagiri
srivatsa vaddagiri
152
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1
100.00%
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152
100.00%
1
100.00%


fs_initcall(kvm_spinlock_debugfs);
#else  /* !CONFIG_KVM_DEBUG_FS */


static inline void add_stats(enum kvm_contention_stat var, u32 val)
{
}

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srivatsa vaddagiri
srivatsa vaddagiri
13
100.00%
1
100.00%
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13
100.00%
1
100.00%



static inline u64 spin_time_start(void)
{
	return 0;
}

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srivatsa vaddagiri
srivatsa vaddagiri
12
100.00%
1
100.00%
Total
12
100.00%
1
100.00%



static inline void spin_time_accum_blocked(u64 start)
{
}
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srivatsa vaddagiri
srivatsa vaddagiri
9
100.00%
1
100.00%
Total
9
100.00%
1
100.00%

#endif  /* CONFIG_KVM_DEBUG_FS */


struct kvm_lock_waiting {
	
struct arch_spinlock *lock;
	
__ticket_t want;
};

/* cpus 'waiting' on a spinlock to become available */

static cpumask_t waiting_cpus;

/* Track spinlock on which a cpu is waiting */
static DEFINE_PER_CPU(struct kvm_lock_waiting, klock_waiting);



__visible void kvm_lock_spinning(struct arch_spinlock *lock, __ticket_t want)
{
	struct kvm_lock_waiting *w;
	int cpu;
	u64 start;
	unsigned long flags;
	__ticket_t head;

	if (in_nmi())
		return;

	w = this_cpu_ptr(&klock_waiting);
	cpu = smp_processor_id();
	start = spin_time_start();

	/*
         * Make sure an interrupt handler can't upset things in a
         * partially setup state.
         */
	local_irq_save(flags);

	/*
         * The ordering protocol on this is that the "lock" pointer
         * may only be set non-NULL if the "want" ticket is correct.
         * If we're updating "want", we must first clear "lock".
         */
	w->lock = NULL;
	smp_wmb();
	w->want = want;
	smp_wmb();
	w->lock = lock;

	add_stats(TAKEN_SLOW, 1);

	/*
         * This uses set_bit, which is atomic but we should not rely on its
         * reordering gurantees. So barrier is needed after this call.
         */
	cpumask_set_cpu(cpu, &waiting_cpus);

	barrier();

	/*
         * Mark entry to slowpath before doing the pickup test to make
         * sure we don't deadlock with an unlocker.
         */
	__ticket_enter_slowpath(lock);

	/* make sure enter_slowpath, which is atomic does not cross the read */
	smp_mb__after_atomic();

	/*
         * check again make sure it didn't become free while
         * we weren't looking.
         */
	head = READ_ONCE(lock->tickets.head);
	if (__tickets_equal(head, want)) {
		add_stats(TAKEN_SLOW_PICKUP, 1);
		goto out;
	}

	/*
         * halt until it's our turn and kicked. Note that we do safe halt
         * for irq enabled case to avoid hang when lock info is overwritten
         * in irq spinlock slowpath and no spurious interrupt occur to save us.
         */
	if (arch_irqs_disabled_flags(flags))
		halt();
	else
		safe_halt();

out:
	cpumask_clear_cpu(cpu, &waiting_cpus);
	w->lock = NULL;
	local_irq_restore(flags);
	spin_time_accum_blocked(start);
}
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srivatsa vaddagiri
srivatsa vaddagiri
169
88.95%
1
25.00%
raghavendra k t* (same as raghavendra koushik)
raghavendra k t* (same as raghavendra koushik)
18
9.47%
1
25.00%
christoph lameter
christoph lameter
2
1.05%
1
25.00%
andi kleen
andi kleen
1
0.53%
1
25.00%
Total
190
100.00%
4
100.00%


PV_CALLEE_SAVE_REGS_THUNK(kvm_lock_spinning);

/* Kick vcpu waiting on @lock->head to reach value @ticket */


static void kvm_unlock_kick(struct arch_spinlock *lock, __ticket_t ticket)
{
	int cpu;

	add_stats(RELEASED_SLOW, 1);
	for_each_cpu(cpu, &waiting_cpus) {
		const struct kvm_lock_waiting *w = &per_cpu(klock_waiting, cpu);
		if (READ_ONCE(w->lock) == lock &&
		    READ_ONCE(w->want) == ticket) {
			add_stats(RELEASED_SLOW_KICKED, 1);
			kvm_kick_cpu(cpu);
			break;
		}
	}
}

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srivatsa vaddagiri
srivatsa vaddagiri
79
97.53%
1
50.00%
raghavendra k t* (same as raghavendra koushik)
raghavendra k t* (same as raghavendra koushik)
2
2.47%
1
50.00%
Total
81
100.00%
2
100.00%

#endif /* !CONFIG_QUEUED_SPINLOCKS */

/*
 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
 */


void __init kvm_spinlock_init(void)
{
	if (!kvm_para_available())
		return;
	/* Does host kernel support KVM_FEATURE_PV_UNHALT? */
	if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
		return;

#ifdef CONFIG_QUEUED_SPINLOCKS
	__pv_init_lock_hash();
	pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
	pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
	pv_lock_ops.wait = kvm_wait;
	pv_lock_ops.kick = kvm_kick_cpu;
#else /* !CONFIG_QUEUED_SPINLOCKS */
	pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(kvm_lock_spinning);
	pv_lock_ops.unlock_kick = kvm_unlock_kick;
#endif
}

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srivatsa vaddagiri
srivatsa vaddagiri
40
51.28%
1
33.33%
waiman long
waiman long
36
46.15%
1
33.33%
ingo molnar
ingo molnar
2
2.56%
1
33.33%
Total
78
100.00%
3
100.00%



static __init int kvm_spinlock_init_jump(void)
{
	if (!kvm_para_available())
		return 0;
	if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
		return 0;

	static_key_slow_inc(&paravirt_ticketlocks_enabled);
	printk(KERN_INFO "KVM setup paravirtual spinlock\n");

	return 0;
}
Contributors
Person
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raghavendra k t* (same as raghavendra koushik)
raghavendra k t* (same as raghavendra koushik)
44
100.00%
1
100.00%
Total
44
100.00%
1
100.00%


early_initcall(kvm_spinlock_init_jump);

#endif	/* CONFIG_PARAVIRT_SPINLOCKS */
Overall Contributors
Person
Tokens
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CommitProp
gleb natapov
gleb natapov
1190
39.05%
8
17.39%
srivatsa vaddagiri
srivatsa vaddagiri
841
27.60%
1
2.17%
glauber costa
glauber costa
275
9.03%
1
2.17%
michael s. tsirkin
michael s. tsirkin
148
4.86%
2
4.35%
marcelo tosatti
marcelo tosatti
128
4.20%
5
10.87%
waiman long
waiman long
108
3.54%
1
2.17%
paolo bonzini
paolo bonzini
101
3.31%
2
4.35%
raghavendra k t* (same as raghavendra koushik)
raghavendra k t* (same as raghavendra koushik)
71
2.33%
3
6.52%
prarit bhargava
prarit bhargava
36
1.18%
1
2.17%
christoph lameter
christoph lameter
26
0.85%
1
2.17%
rik van riel
rik van riel
22
0.72%
1
2.17%
li zhong
li zhong
19
0.62%
1
2.17%
chris wright
chris wright
11
0.36%
1
2.17%
frederic weisbecker
frederic weisbecker
11
0.36%
2
4.35%
masami hiramatsu
masami hiramatsu
10
0.33%
1
2.17%
ingo molnar
ingo molnar
7
0.23%
2
4.35%
ulrich obergfell
ulrich obergfell
7
0.23%
2
4.35%
shuah khan
shuah khan
7
0.23%
1
2.17%
alok kataria
alok kataria
5
0.16%
1
2.17%
dave hansen
dave hansen
5
0.16%
2
4.35%
sasha levin
sasha levin
5
0.16%
1
2.17%
borislav petkov
borislav petkov
4
0.13%
1
2.17%
jason wang
jason wang
3
0.10%
1
2.17%
florian westphal
florian westphal
3
0.10%
1
2.17%
nicholas krause
nicholas krause
2
0.07%
1
2.17%
tim gardner
tim gardner
1
0.03%
1
2.17%
andi kleen
andi kleen
1
0.03%
1
2.17%
Total
3047
100.00%
46
100.00%
  
Directory: arch/x86/kernel

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