linux-kernel - [PATCH] KVM: x86: avoid useless copy of cpufreq policy

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Message-Id: <1582883764-26125-2-git-send-email-pbonzini@redhat.com>
Date:   Fri, 28 Feb 2020 10:56:04 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     hch@....de
Subject: [PATCH] KVM: x86: avoid useless copy of cpufreq policy

struct cpufreq_policy is quite big and it is not a good idea
to allocate one on the stack.  Just use cpufreq_cpu_get and
cpufreq_cpu_put which is even simpler.

Reported-by: Christoph Hellwig <hch@....de>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/x86.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 359fcd395132..bcb6b676608b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7190,15 +7190,15 @@ static void kvm_timer_init(void)
 
 	if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) {
 #ifdef CONFIG_CPU_FREQ
-		struct cpufreq_policy policy;
+		struct cpufreq_policy *policy;
 		int cpu;
 
-		memset(&policy, 0, sizeof(policy));
 		cpu = get_cpu();
-		cpufreq_get_policy(&policy, cpu);
-		if (policy.cpuinfo.max_freq)
-			max_tsc_khz = policy.cpuinfo.max_freq;
+		policy = cpufreq_cpu_get(cpu);
+		if (policy && policy->cpuinfo.max_freq)
+			max_tsc_khz = policy->cpuinfo.max_freq;
 		put_cpu();
+		cpufreq_cpu_put(policy);
 #endif
 		cpufreq_register_notifier(&kvmclock_cpufreq_notifier_block,
 					  CPUFREQ_TRANSITION_NOTIFIER);
-- 
1.8.3.1