From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Jones Subject: [PATCH v4 06/11] KVM: arm/arm64: use vcpu requests for power_off Date: Tue, 16 May 2017 04:20:30 +0200 Message-ID: <20170516022035.7674-7-drjones@redhat.com> References: <20170516022035.7674-1-drjones@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: marc.zyngier@arm.com, cdall@linaro.org, pbonzini@redhat.com To: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Return-path: In-Reply-To: <20170516022035.7674-1-drjones@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu List-Id: kvm.vger.kernel.org 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, fixing the race. Signed-off-by: Andrew Jones --- virt/kvm/arm/psci.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c index f68be2cc6256..f189d0ad30d5 100644 --- a/virt/kvm/arm/psci.c +++ b/virt/kvm/arm/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