From 5a3d883a59b3fe8dc8775c7a79200a5b11a6761e Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Tue, 29 Sep 2015 16:27:24 +0200 Subject: KVM: s390: switch to get_tod_clock() and fix STP sync races Nobody except early.c makes use of store_tod_clock() to handle the cc. So if we would get a cc != 0, we would be in more trouble. Let's replace all users with get_tod_clock(). Returning a cc on an ioctl sounded strange either way. We can now also easily move the get_tod_clock() call into the preempt_disable() section. This is in fact necessary to make the STP sync work as expected. Otherwise the host TOD could change and we would end up with a wrong epoch calculation. Reviewed-by: Christian Borntraeger Signed-off-by: David Hildenbrand Signed-off-by: Christian Borntraeger --- arch/s390/kvm/kvm-s390.c | 18 ++++-------------- 1 file changed, 4 insertions(+), 14 deletions(-) (limited to 'arch/s390/kvm/kvm-s390.c') diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 0a67c40eece9..a0907795f31d 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -523,19 +523,14 @@ static int kvm_s390_set_tod_low(struct kvm *kvm, struct kvm_device_attr *attr) { struct kvm_vcpu *cur_vcpu; unsigned int vcpu_idx; - u64 host_tod, gtod; - int r; + u64 gtod; if (copy_from_user(>od, (void __user *)attr->addr, sizeof(gtod))) return -EFAULT; - r = store_tod_clock(&host_tod); - if (r) - return r; - mutex_lock(&kvm->lock); preempt_disable(); - kvm->arch.epoch = gtod - host_tod; + kvm->arch.epoch = gtod - get_tod_clock(); kvm_s390_vcpu_block_all(kvm); kvm_for_each_vcpu(vcpu_idx, cur_vcpu, kvm) cur_vcpu->arch.sie_block->epoch = kvm->arch.epoch; @@ -581,15 +576,10 @@ static int kvm_s390_get_tod_high(struct kvm *kvm, struct kvm_device_attr *attr) static int kvm_s390_get_tod_low(struct kvm *kvm, struct kvm_device_attr *attr) { - u64 host_tod, gtod; - int r; - - r = store_tod_clock(&host_tod); - if (r) - return r; + u64 gtod; preempt_disable(); - gtod = host_tod + kvm->arch.epoch; + gtod = get_tod_clock() + kvm->arch.epoch; preempt_enable(); if (copy_to_user((void __user *)attr->addr, >od, sizeof(gtod))) return -EFAULT; -- cgit v1.2.3