[PATCH 28/45] KVM: Use get/put_online_cpus_atomic() to prevent CPU offline
From: Srivatsa S. Bhat <hidden>
Date: 2013-06-23 13:47:40
Also in:
kvm, linux-arch, linux-pm, linuxppc-dev, lkml
Subsystem:
kernel virtual machine (kvm), the rest · Maintainers:
Paolo Bonzini, Linus Torvalds
Once stop_machine() is gone from the CPU offline path, we won't be able to depend on disabling preemption to prevent CPUs from going offline from under us. Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, while invoking from atomic context. Cc: Gleb Natapov <redacted> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: kvm@vger.kernel.org Signed-off-by: Srivatsa S. Bhat <redacted> --- virt/kvm/kvm_main.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 302681c..5bbfa30 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -174,7 +174,7 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) zalloc_cpumask_var(&cpus, GFP_ATOMIC); - me = get_cpu(); + me = get_online_cpus_atomic(); kvm_for_each_vcpu(i, vcpu, kvm) { kvm_make_request(req, vcpu); cpu = vcpu->cpu;
@@ -192,7 +192,7 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) smp_call_function_many(cpus, ack_flush, NULL, 1); else called = false; - put_cpu(); + put_online_cpus_atomic(); free_cpumask_var(cpus); return called; }
@@ -1707,11 +1707,11 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu) ++vcpu->stat.halt_wakeup; } - me = get_cpu(); + me = get_online_cpus_atomic(); if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) if (kvm_arch_vcpu_should_kick(vcpu)) smp_send_reschedule(cpu); - put_cpu(); + put_online_cpus_atomic(); } EXPORT_SYMBOL_GPL(kvm_vcpu_kick); #endif /* !CONFIG_S390 */