System shutdown is currently using request-less VCPU kicks. This leaves open a tiny race window, as it doesn't ensure the state change to power_off is seen by a VCPU just about to enter guest mode. VCPU requests, OTOH, are guaranteed to be seen (see "Ensuring Requests Are Seen" of Documentation/virtual/kvm/vcpu-requests.rst) This patch applies the EXIT request used by pause to power_off, closing the race window and also allowing us to remove the final check of power_off in VCPU RUN, as the final check for requests is sufficient.
Signed-off-by: Andrew Jones <[email protected]> --- arch/arm/kvm/arm.c | 3 +-- arch/arm/kvm/psci.c | 5 ++--- 2 files changed, 3 insertions(+), 5 deletions(-) diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 7be0d9b0c63a..26d9d4d72853 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -670,8 +670,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) smp_store_mb(vcpu->mode, IN_GUEST_MODE); if (ret <= 0 || need_new_vmid_gen(vcpu->kvm) || - kvm_request_pending(vcpu) || - vcpu->arch.power_off) { + kvm_request_pending(vcpu)) { vcpu->mode = OUTSIDE_GUEST_MODE; local_irq_enable(); kvm_pmu_sync_hwstate(vcpu); diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c index f68be2cc6256..f189d0ad30d5 100644 --- a/arch/arm/kvm/psci.c +++ b/arch/arm/kvm/psci.c @@ -179,10 +179,9 @@ static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type) * after this call is handled and before the VCPUs have been * re-initialized. */ - kvm_for_each_vcpu(i, tmp, vcpu->kvm) { + kvm_for_each_vcpu(i, tmp, vcpu->kvm) tmp->arch.power_off = true; - kvm_vcpu_kick(tmp); - } + kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_VCPU_EXIT); memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event)); vcpu->run->system_event.type = type; -- 2.9.3 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
