From 7dfc63cf977447e09b1072911c22564f900fc578 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 15 May 2014 14:25:25 +0200 Subject: KVM: s390: allow only one SIGP STOP (AND STORE STATUS) at a time A SIGP STOP (AND STORE STATUS) order is complete as soon as the VCPU has been stopped. This patch makes sure that only one SIGP STOP (AND STORE STATUS) may be pending at a time (as defined by the architecture). If the action_bits are still set, a SIGP STOP has been issued but not completed yet. The VCPU is busy for further SIGP STOP orders. Also set the CPUSTAT_STOP_INT after the action_bits variable has been modified (the same order that is used when injecting a KVM_S390_SIGP_STOP from userspace). Both changes are needed in preparation for a user space driven VCPU state change (to avoid race conditions). Signed-off-by: David Hildenbrand Reviewed-by: Cornelia Huck Reviewed-by: Christian Borntraeger Signed-off-by: Christian Borntraeger --- arch/s390/kvm/sigp.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'arch/s390/kvm/sigp.c') diff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c index 43079a48cc98..fd7fb5c5ef5d 100644 --- a/arch/s390/kvm/sigp.c +++ b/arch/s390/kvm/sigp.c @@ -136,6 +136,11 @@ static int __inject_sigp_stop(struct kvm_s390_local_interrupt *li, int action) inti->type = KVM_S390_SIGP_STOP; spin_lock_bh(&li->lock); + if (li->action_bits & ACTION_STOP_ON_STOP) { + /* another SIGP STOP is pending */ + rc = SIGP_CC_BUSY; + goto out; + } if ((atomic_read(li->cpuflags) & CPUSTAT_STOPPED)) { kfree(inti); if ((action & ACTION_STORE_ON_STOP) != 0) @@ -144,8 +149,8 @@ static int __inject_sigp_stop(struct kvm_s390_local_interrupt *li, int action) } list_add_tail(&inti->list, &li->list); atomic_set(&li->active, 1); - atomic_set_mask(CPUSTAT_STOP_INT, li->cpuflags); li->action_bits |= action; + atomic_set_mask(CPUSTAT_STOP_INT, li->cpuflags); if (waitqueue_active(li->wq)) wake_up_interruptible(li->wq); out: -- cgit