From 60417fcc2b0235dfe3dcd589c56dbe3ea1a64c54 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Tue, 29 Sep 2015 16:20:36 +0200 Subject: KVM: s390: factor out reading of the guest TOD clock Let's factor this out and always use get_tod_clock_fast() when reading the guest TOD. STORE CLOCK FAST does not do serialization and, therefore, might result in some fuzziness between different processors in a way that subsequent calls on different CPUs might have time stamps that are earlier. This semantics is fine though for all KVM use cases. To make it obvious that the new function has STORE CLOCK FAST semantics we name it kvm_s390_get_tod_clock_fast. With this patch, we only have a handful of places were we have to care about STP sync (using preempt_disable() logic). Reviewed-by: Christian Borntraeger Signed-off-by: David Hildenbrand Signed-off-by: Christian Borntraeger --- arch/s390/kvm/kvm-s390.c | 4 +--- 1 file changed, 1 insertion(+), 3 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 87bd602f326c..618c85411a51 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -568,9 +568,7 @@ static int kvm_s390_get_tod_low(struct kvm *kvm, struct kvm_device_attr *attr) { u64 gtod; - preempt_disable(); - gtod = get_tod_clock() + kvm->arch.epoch; - preempt_enable(); + gtod = kvm_s390_get_tod_clock_fast(kvm); if (copy_to_user((void __user *)attr->addr, >od, sizeof(gtod))) return -EFAULT; VM_EVENT(kvm, 3, "QUERY: TOD base: 0x%llx\n", gtod); -- cgit v1.2.3