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From: Anna-Maria Gleixner <anna-maria@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	rt@linutronix.de,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Gleb Natapov <gleb@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Radim Krcmar <rkrcmar@redhat.com>,
	kvm@vger.kernel.org,
	Anna-Maria Gleixner <anna-maria@linutronix.de>
Subject: [patch V2 32/67] x86/kvm/kvmclock: Convert to hotplug state machine
Date: Wed, 13 Jul 2016 17:16:33 -0000
Message-ID: <20160713153335.542880859@linutronix.de> (raw)
In-Reply-To: <20160713153219.128052238@linutronix.de>


[-- Attachment #0: 0031-x86-kvm-kvmclock-Convert-to-hotplug-state-machine.patch --]
[-- Type: text/plain, Size: 3393 bytes --]

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

We assumed that the priority ordering was ment to invoke the online
callback as the last step. In the original code this also invoked the
down prepare callback as the last step. With the symmetric state
machine the down prepare callback is now the first step.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm@vger.kernel.org
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
 arch/x86/kvm/x86.c         |   33 ++++++++-------------------------
 include/linux/cpuhotplug.h |    1 +
 2 files changed, 9 insertions(+), 25 deletions(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5552,9 +5552,10 @@ int kvm_fast_pio_out(struct kvm_vcpu *vc
 }
 EXPORT_SYMBOL_GPL(kvm_fast_pio_out);
 
-static void tsc_bad(void *info)
+static int kvmclock_cpu_down_prep(unsigned int cpu)
 {
 	__this_cpu_write(cpu_tsc_khz, 0);
+	return 0;
 }
 
 static void tsc_khz_changed(void *data)
@@ -5659,33 +5660,18 @@ static struct notifier_block kvmclock_cp
 	.notifier_call  = kvmclock_cpufreq_notifier
 };
 
-static int kvmclock_cpu_notifier(struct notifier_block *nfb,
-					unsigned long action, void *hcpu)
+static int kvmclock_cpu_online(unsigned int cpu)
 {
-	switch (action) {
-		case CPU_ONLINE:
-		case CPU_DOWN_FAILED:
-			tsc_khz_changed(NULL);
-			break;
-		case CPU_DOWN_PREPARE:
-			tsc_bad(NULL);
-			break;
-	}
-	return NOTIFY_OK;
+	tsc_khz_changed(NULL);
+	return 0;
 }
 
-static struct notifier_block kvmclock_cpu_notifier_block = {
-	.notifier_call  = kvmclock_cpu_notifier,
-	.priority = -INT_MAX
-};
-
 static void kvm_timer_init(void)
 {
 	int cpu;
 
 	max_tsc_khz = tsc_khz;
 
-	cpu_notifier_register_begin();
 	if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) {
 #ifdef CONFIG_CPU_FREQ
 		struct cpufreq_policy policy;
@@ -5700,12 +5686,9 @@ static void kvm_timer_init(void)
 					  CPUFREQ_TRANSITION_NOTIFIER);
 	}
 	pr_debug("kvm: max_tsc_khz = %ld\n", max_tsc_khz);
-	for_each_online_cpu(cpu)
-		smp_call_function_single(cpu, tsc_khz_changed, NULL, 1);
-
-	__register_hotcpu_notifier(&kvmclock_cpu_notifier_block);
-	cpu_notifier_register_done();
 
+	cpuhp_setup_state(CPUHP_AP_X86_KVM_CLK_ONLINE, "AP_X86_KVM_CLK_ONLINE",
+			  kvmclock_cpu_online, kvmclock_cpu_down_prep);
 }
 
 static DEFINE_PER_CPU(struct kvm_vcpu *, current_vcpu);
@@ -5894,7 +5877,7 @@ void kvm_arch_exit(void)
 	if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
 		cpufreq_unregister_notifier(&kvmclock_cpufreq_notifier_block,
 					    CPUFREQ_TRANSITION_NOTIFIER);
-	unregister_hotcpu_notifier(&kvmclock_cpu_notifier_block);
+	cpuhp_remove_state_nocalls(CPUHP_AP_X86_KVM_CLK_ONLINE);
 #ifdef CONFIG_X86_64
 	pvclock_gtod_unregister_notifier(&pvclock_gtod_notifier);
 #endif
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -57,6 +57,7 @@ enum cpuhp_state {
 	CPUHP_AP_ONLINE_DYN,
 	CPUHP_AP_ONLINE_DYN_END		= CPUHP_AP_ONLINE_DYN + 30,
 	CPUHP_AP_X86_HPET_ONLINE,
+	CPUHP_AP_X86_KVM_CLK_ONLINE,
 	CPUHP_AP_ACTIVE,
 	CPUHP_ONLINE,
 };



  parent reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20160713153219.128052238@linutronix.de>
2016-07-13 17:16 ` [patch V2 31/67] KVM/x86: Remove superfluous SMP function call Anna-Maria Gleixner
2016-07-14  8:21   ` Paolo Bonzini
2016-07-13 17:16 ` Anna-Maria Gleixner [this message]
2016-07-13 17:16 ` [patch V2 36/67] virt: Convert kvm hotplug to state machine Anna-Maria Gleixner
2016-07-13 17:16 ` [patch V2 44/67] arm/kvm/vgic: Convert to hotplug " Anna-Maria Gleixner
2016-07-13 17:16 ` [patch V2 45/67] arm/kvm/arch_timer: " Anna-Maria Gleixner
2016-07-13 17:17 ` [patch V2 60/67] KVM/arm/arm64/vgic-new: " Anna-Maria Gleixner
2016-07-14 13:08   ` Marc Zyngier

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