Previously, Ladi was working on enabling TSC page clocksource for nested
Hyper-V-on-KVM workloads. He found out that if Hyper-V frequency MSRs are
exposed to L1 as well as INVTSC flag Hyper-V enables TSC page clocksource
to its guests. Qemu doesn't pass INVTSC by default as it is a migration
blocker.
I found out there's a different way to make Hyper-V like us: expose
Reenlightenment MSRs to it. KVM doesn't fully support the feature as
we're still unable to migrate nested environments but rudimentary support
we have there (kvm/queue only currently) is enough.
Enable Hyper-V reenlightenment MSRs and expose frequency MSRs even without
INVTSC to make things work.
[My first patches for Qemu, please be nice :-) ]
Vitaly Kuznetsov (2):
i386/kvm: add support for Hyper-V reenlightenment MSRs
i386/kvm: lower requirements for Hyper-V frequency MSRs exposure
target/i386/cpu.h | 3 +++
target/i386/hyperv-proto.h | 9 ++++++++-
target/i386/kvm.c | 35 ++++++++++++++++++++++++++++++++++-
3 files changed, 45 insertions(+), 2 deletions(-)
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2.14.3