kernel-packages team mailing list archive

[Joseph Salisbury <joseph.salisbury@xxxxxxxxxxxxx>]

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 wily

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https://bugs.launchpad.net/bugs/1567167

Title:
  Ubuntu 15.10: tsc_offset is error for hot-plugged vcpu.

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  1. when hot plug vcpu, KVM will call kvm_write_tsc set the new vcpu's
  tsc_offset to host tsc.  The new vcpu's tsc_offsets is greatly
  different from preallocated vcpu's tsc_offset.

  2. For redhat 6.x, the vm will show warning and turn off TSC clock.
  kernel: CPU 1 got hotplugged
  kernel: kvm-clock: cpu 1, msr 0:282367c1, secondary cpu clock
  kernel: TSC synchronization [CPU#0 -> CPU#1]:
  kernel: Measured 150076598781 cycles TSC warp between CPUs, turning off TSC clock.
  kernel: Marking TSC unstable due to check_tsc_sync_source failed

  3. I think should set the new vcpu's tsc_offset to
  kvm->arch.cur_tsc_offset.

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