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authorDavid Hildenbrand <dahi@linux.vnet.ibm.com>2015-09-29 16:27:24 +0200
committerChristian Borntraeger <borntraeger@de.ibm.com>2015-10-13 15:50:34 +0200
commit5a3d883a59b3fe8dc8775c7a79200a5b11a6761e (patch)
treea1b60ce1821f86e3a6fc30e32ba3228d5525f6f6 /arch/s390/kvm/priv.c
parent238293b14d9b1f5689e2aa68710000b0f25aa612 (diff)
downloadlinux-5a3d883a59b3fe8dc8775c7a79200a5b11a6761e.tar.bz2
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 <borntraeger@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to 'arch/s390/kvm/priv.c')
-rw-r--r--arch/s390/kvm/priv.c8
1 files changed, 2 insertions, 6 deletions
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 4d21dc4d1a84..b253de5b8945 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -34,7 +34,7 @@
static int handle_set_clock(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu *cpup;
- s64 hostclk, val;
+ s64 val;
int i, rc;
ar_t ar;
u64 op2;
@@ -49,15 +49,11 @@ static int handle_set_clock(struct kvm_vcpu *vcpu)
if (rc)
return kvm_s390_inject_prog_cond(vcpu, rc);
- if (store_tod_clock(&hostclk)) {
- kvm_s390_set_psw_cc(vcpu, 3);
- return 0;
- }
VCPU_EVENT(vcpu, 3, "SCK: setting guest TOD to 0x%llx", val);
- val = (val - hostclk) & ~0x3fUL;
mutex_lock(&vcpu->kvm->lock);
preempt_disable();
+ val = (val - get_tod_clock()) & ~0x3fUL;
kvm_for_each_vcpu(i, cpup, vcpu->kvm)
cpup->arch.sie_block->epoch = val;
preempt_enable();