Commit 34226b6b authored Mar 24, 2018 by Wanpeng Li Committed by Radim Krčmář Mar 28, 2018

KVM: X86: Fix setup the virt_spin_lock_key before static key get initialized



 static_key_disable_cpuslocked(): static key 'virt_spin_lock_key+0x0/0x20' used before call to jump_label_init()
 WARNING: CPU: 0 PID: 0 at kernel/jump_label.c:161 static_key_disable_cpuslocked+0x61/0x80
 RIP: 0010:static_key_disable_cpuslocked+0x61/0x80
 Call Trace:
  static_key_disable+0x16/0x20
  start_kernel+0x192/0x4b3
  secondary_startup_64+0xa5/0xb0

Qspinlock will be choosed when dedicated pCPUs are available, however, the
static virt_spin_lock_key is set in kvm_spinlock_init() before jump_label_init()
has been called, which will result in a WARN(). This patch fixes it by delaying
the virt_spin_lock_key setup to .smp_prepare_cpus().

Reported-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Fixes: b2798ba0 ("KVM: X86: Choose qspinlock when dedicated physical CPUs are available")
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

parent 1f97e01a

arch/x86/kernel/kvm.c

+9 −3

Original line number	Diff line number	Diff line
		@@ -454,6 +454,13 @@ static void __init sev_map_percpu_data(void)
		}

		#ifdef CONFIG_SMP
		static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
		{
		native_smp_prepare_cpus(max_cpus);
		if (kvm_para_has_hint(KVM_HINTS_DEDICATED))
		static_branch_disable(&virt_spin_lock_key);
		}

		static void __init kvm_smp_prepare_boot_cpu(void)
		{
		/*
		@@ -557,6 +564,7 @@ static void __init kvm_guest_init(void)
		kvm_setup_vsyscall_timeinfo();

		#ifdef CONFIG_SMP
		smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus;
		smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
		if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
		kvm_cpu_online, kvm_cpu_down_prepare) < 0)
		@@ -737,10 +745,8 @@ void __init kvm_spinlock_init(void)
		if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
		return;

		if (kvm_para_has_hint(KVM_HINTS_DEDICATED)) {
		static_branch_disable(&virt_spin_lock_key);
		if (kvm_para_has_hint(KVM_HINTS_DEDICATED))
		return;
		}

		__pv_init_lock_hash();
		pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;

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