From 1bc5d59c35976d39b39b14f86abb76c08364cf97 Mon Sep 17 00:00:00 2001 From: "Suresh E. Warrier" Date: Mon, 3 Nov 2014 15:52:00 +1100 Subject: [PATCH] KVM: PPC: Book3S HV: Check wait conditions before sleeping in kvmppc_vcore_blocked The kvmppc_vcore_blocked() code does not check for the wait condition after putting the process on the wait queue. This means that it is possible for an external interrupt to become pending, but the vcpu to remain asleep until the next decrementer interrupt. The fix is to make one last check for pending exceptions and ceded state before calling schedule(). Signed-off-by: Suresh Warrier Signed-off-by: Paul Mackerras Signed-off-by: Alexander Graf --- arch/powerpc/kvm/book3s_hv.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index cd7e030087f8..1a7a281be3bd 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1828,9 +1828,29 @@ static void kvmppc_wait_for_exec(struct kvm_vcpu *vcpu, int wait_state) */ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc) { + struct kvm_vcpu *vcpu; + int do_sleep = 1; + DEFINE_WAIT(wait); prepare_to_wait(&vc->wq, &wait, TASK_INTERRUPTIBLE); + + /* + * Check one last time for pending exceptions and ceded state after + * we put ourselves on the wait queue + */ + list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) { + if (vcpu->arch.pending_exceptions || !vcpu->arch.ceded) { + do_sleep = 0; + break; + } + } + + if (!do_sleep) { + finish_wait(&vc->wq, &wait); + return; + } + vc->vcore_state = VCORE_SLEEPING; spin_unlock(&vc->lock); schedule(); -- 2.39.5