[Qemu-devel] [PATCH 0/4] Allow migration with invtsc if there's no frequency mismatch

[Eduardo Habkost <ehabkost@redhat.com>]

This series makes QEMU accept migration with invtsc if:

a) The destination host has a matching TSC frequency; or
b) The destination host has TSC scaling available.

There are two cases where we can ensure the above conditions.
This series implements both:

1) tsc-khz explicitly set on the configuration. This case is
   trivial because the current code already refuses to start if
   there's a TSC frequency mismatch and tsc-khz is explicitly
   configured. (Implemented by patch 2/4)

2) A newer machine-type is being used. This means we know that
   the migration destination is running a QEMU version that will
   check for (a) and (b) on migration even if tsc-khz is not set
   explicitly. (Implemented by patch 4/4)

Eduardo Habkost (4):
  kvm: Simplify invtsc check
  kvm: Allow invtsc migration if tsc-khz is set explicitly
  pc: Add 2.9 machine-types
  kvm: Allow migration with invtsc

 include/hw/i386/pc.h |  6 ++++++
 target/i386/cpu.h    |  1 +
 hw/i386/pc_piix.c    | 15 ++++++++++++---
 hw/i386/pc_q35.c     | 13 +++++++++++--
 target/i386/cpu.c    |  1 +
 target/i386/kvm.c    | 32 ++++++++++++++++++--------------
 6 files changed, 49 insertions(+), 19 deletions(-)

-- 
2.7.4