Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.6 kernel[0].
If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'. If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'. Once testing of the upstream kernel is complete, please mark this bug as "Confirmed". Thanks in advance. [0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.6-rc4-wily/ ** Changed in: linux (Ubuntu) Importance: Undecided => Medium ** Changed in: linux (Ubuntu) Status: Confirmed => Incomplete ** Tags added: kernel-da-key -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. 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: Incomplete 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; To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1567159/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp