linux-kernel - [PATCH 6/7] KVM: x86: Update cpufreq transition notifier to handle multiple CPUs

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Message-Id: <adcf2b6e181d2ad2ab1b7038ba898eb4f4e53906.1552545525.git.viresh.kumar@linaro.org>
Date:   Thu, 14 Mar 2019 12:12:52 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rafael Wysocki <rjw@...ysocki.net>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Cc:     Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 6/7] KVM: x86: Update cpufreq transition notifier to handle multiple CPUs

The cpufreq core currently calls the cpufreq transition notifier
callback once for each affected CPU. This is going to change soon and
the cpufreq core will call the callback only once for each cpufreq
policy. The callback must look at the newly added field in struct
cpufreq_freqs, "cpus", which contains policy->related_cpus (both
online/offline CPUs) and perform per-cpu actions for them if any.

This patch updates kvmclock_cpufreq_notifier() to use the new "cpus"
field and perform the per-cpu activity for all online CPUs in this
cpumask.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 arch/x86/kvm/x86.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 941f932373d0..24eb6123391d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6648,10 +6648,8 @@ static void kvm_hyperv_tsc_notifier(void)
 }
 #endif
 
-static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
-				     void *data)
+static void __kvmclock_cpufreq_notifier(struct cpufreq_freqs *freq, int cpu)
 {
-	struct cpufreq_freqs *freq = data;
 	struct kvm *kvm;
 	struct kvm_vcpu *vcpu;
 	int i, send_ipi = 0;
@@ -6695,17 +6693,12 @@ static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long va
 	 *
 	 */
 
-	if (val == CPUFREQ_PRECHANGE && freq->old > freq->new)
-		return 0;
-	if (val == CPUFREQ_POSTCHANGE && freq->old < freq->new)
-		return 0;
-
-	smp_call_function_single(freq->cpu, tsc_khz_changed, freq, 1);
+	smp_call_function_single(cpu, tsc_khz_changed, freq, 1);
 
 	spin_lock(&kvm_lock);
 	list_for_each_entry(kvm, &vm_list, vm_list) {
 		kvm_for_each_vcpu(i, vcpu, kvm) {
-			if (vcpu->cpu != freq->cpu)
+			if (vcpu->cpu != cpu)
 				continue;
 			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
 			if (vcpu->cpu != smp_processor_id())
@@ -6727,8 +6720,24 @@ static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long va
 		 * guest context is entered kvmclock will be updated,
 		 * so the guest will not see stale values.
 		 */
-		smp_call_function_single(freq->cpu, tsc_khz_changed, freq, 1);
+		smp_call_function_single(cpu, tsc_khz_changed, freq, 1);
 	}
+}
+
+static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
+				     void *data)
+{
+	struct cpufreq_freqs *freq = data;
+	int cpu;
+
+	if (val == CPUFREQ_PRECHANGE && freq->old > freq->new)
+		return 0;
+	if (val == CPUFREQ_POSTCHANGE && freq->old < freq->new)
+		return 0;
+
+	for_each_cpu_and(cpu, freq->cpus, cpu_online_mask)
+		__kvmclock_cpufreq_notifier(freq, cpu);
+
 	return 0;
 }
 
-- 
2.21.0.rc0.269.g1a574e7a288b