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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>
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parent
238293b14d
commit
5a3d883a59
2 changed files with 6 additions and 20 deletions
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@ -523,19 +523,14 @@ static int kvm_s390_set_tod_low(struct kvm *kvm, struct kvm_device_attr *attr)
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{
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struct kvm_vcpu *cur_vcpu;
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unsigned int vcpu_idx;
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u64 host_tod, gtod;
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int r;
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u64 gtod;
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if (copy_from_user(>od, (void __user *)attr->addr, sizeof(gtod)))
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return -EFAULT;
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r = store_tod_clock(&host_tod);
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if (r)
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return r;
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mutex_lock(&kvm->lock);
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preempt_disable();
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kvm->arch.epoch = gtod - host_tod;
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kvm->arch.epoch = gtod - get_tod_clock();
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kvm_s390_vcpu_block_all(kvm);
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kvm_for_each_vcpu(vcpu_idx, cur_vcpu, kvm)
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cur_vcpu->arch.sie_block->epoch = kvm->arch.epoch;
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@ -581,15 +576,10 @@ static int kvm_s390_get_tod_high(struct kvm *kvm, struct kvm_device_attr *attr)
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static int kvm_s390_get_tod_low(struct kvm *kvm, struct kvm_device_attr *attr)
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{
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u64 host_tod, gtod;
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int r;
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r = store_tod_clock(&host_tod);
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if (r)
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return r;
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u64 gtod;
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preempt_disable();
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gtod = host_tod + kvm->arch.epoch;
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gtod = get_tod_clock() + kvm->arch.epoch;
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preempt_enable();
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if (copy_to_user((void __user *)attr->addr, >od, sizeof(gtod)))
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return -EFAULT;
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@ -34,7 +34,7 @@
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static int handle_set_clock(struct kvm_vcpu *vcpu)
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{
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struct kvm_vcpu *cpup;
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s64 hostclk, val;
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s64 val;
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int i, rc;
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ar_t ar;
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u64 op2;
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@ -49,15 +49,11 @@ static int handle_set_clock(struct kvm_vcpu *vcpu)
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if (rc)
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return kvm_s390_inject_prog_cond(vcpu, rc);
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if (store_tod_clock(&hostclk)) {
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kvm_s390_set_psw_cc(vcpu, 3);
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return 0;
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}
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VCPU_EVENT(vcpu, 3, "SCK: setting guest TOD to 0x%llx", val);
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val = (val - hostclk) & ~0x3fUL;
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mutex_lock(&vcpu->kvm->lock);
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preempt_disable();
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val = (val - get_tod_clock()) & ~0x3fUL;
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kvm_for_each_vcpu(i, cpup, vcpu->kvm)
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cpup->arch.sie_block->epoch = val;
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preempt_enable();
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