No pending crash reports.
The influence is: After hot plug vcpu, kvm_arch->use_master_clock will never be
true, even if use_master_clock is true before hot plug vcpu.
** Changed in: linux (Ubuntu)
Status: Incomplete => Confirmed
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https://bugs.launchpad.net/bugs/1567159
Title:
Ubuntu 15.10: After hot plug vcpu, kvm_arch->use_master_clock will
never be true.
Status in linux package in Ubuntu:
Confirmed
Bug description:
1. In function kvm_write_tsc, when tsc first matched, do
kvm->arch.nr_vcpus_matched_tsc++;
2. In function pvclock_update_vm_gtod_copy, if vcpus_matched (also
with other conditions meet), ka->use_master_clock will be true;
3. After hot plug vcpu, kvm_arch_vcpu_postcreate and Qemu will call
kvm_write_tsc for the new vcpu. Because the tsc will not match, so do
kvm->arch.nr_vcpus_matched_tsc = 0;
4. For other already existed vcpu will not call kvm_write_tsc, so will
not do kvm->arch.nr_vcpus_matched_tsc++;
5. So vcpus_matched in function pvclock_update_vm_gtod_copy will be
false forever, this cause ka->use_master_clock will never be true;
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