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authorRaghavendra K T <raghavendra.kt@linux.vnet.ibm.com>2013-10-09 14:33:21 +0530
committerGleb Natapov <gleb@redhat.com>2013-10-15 14:15:54 +0300
commit3dbef3e3bf13d74582fe43548f5c570a0cec9b20 (patch)
treed5aebb38746adcf68ce226d5b0f9f3093fc8b9e7 /arch
parent9d05746e7b16d8565dddbe3200faa1e669d23bbf (diff)
downloadlinux-3dbef3e3bf13d74582fe43548f5c570a0cec9b20.tar.gz
KVM: Enable pvspinlock after jump_label_init() to avoid VM hang
We use jump label to enable pv-spinlock. With the changes in (442e0973e927 Merge branch 'x86/jumplabel'), the jump label behaviour has changed that would result in eventual hang of the VM since we would end up in a situation where slow path locks would halt the vcpus but we will not be able to wakeup the vcpu by lock releaser using unlock kick. Similar problem in Xen and more detailed description is available in a945928ea270 (xen: Do not enable spinlocks before jump_label_init() has executed) This patch splits kvm_spinlock_init to separate jump label changes with pvops patching and also make jump label enabling after jump_label_init(). Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Gleb Natapov <gleb@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/kvm.c17
1 files changed, 14 insertions, 3 deletions
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 697b93af02d..a0e2a8a80c9 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -775,11 +775,22 @@ void __init kvm_spinlock_init(void)
if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
return;
- printk(KERN_INFO "KVM setup paravirtual spinlock\n");
+ pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(kvm_lock_spinning);
+ pv_lock_ops.unlock_kick = kvm_unlock_kick;
+}
+
+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");
- pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(kvm_lock_spinning);
- pv_lock_ops.unlock_kick = kvm_unlock_kick;
+ return 0;
}
+early_initcall(kvm_spinlock_init_jump);
+
#endif /* CONFIG_PARAVIRT_SPINLOCKS */