On Wed, Feb 28, 2018 at 02:43:59PM +0100, Vitaly Kuznetsov wrote: > Nested Hyper-V/Windows guest running on top of KVM will use TSC page > clocksource in two cases: > - L0 exposes invariant TSC (CPUID.80000007H:EDX[8]). > - L0 provides Hyper-V Reenlightenment support (CPUID.40000003H:EAX[13]). > > Exposing invariant TSC effectively blocks migration to hosts with different > TSC frequencies, I wonder if TSC scaling on the destination host doesn't allow to relax this requirement? > providing reenlightenment support will be needed when we > start migrating nested workloads. > > Implement rudimentary support for reenlightenment MSRs. For now, these are > just read/write MSRs with no effect. > > Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> > --- > arch/x86/include/asm/kvm_host.h | 4 ++++ > arch/x86/kvm/hyperv.c | 21 +++++++++++++++++++++ > arch/x86/kvm/x86.c | 12 +++++++++++- > 3 files changed, 36 insertions(+), 1 deletion(-) Reviewed-by: Roman Kagan <rkagan@xxxxxxxxxxxxx>
