This is the QEMU part of the changes required for nested Hyper-V to read timestamps with RDTSC + TSC page. Without exposing the frequency MSRs, Windows with the Hyper-V role enabled use the much slower HV_X64_MSR_TIME_REF_COUNT (0x40000020) RDMSR to read timestamps. The new registers are exposed only if the TSC frequency is stable across migration and known, as suggested by Paolo. v1->v2: * deleted an extra empty line in patch 1 * added patch 3 introducing a helper function for the "TSC is stable and known" check (David) Ladi Prosek (4): i386/kvm: use a switch statement for MSR detection i386/kvm: set tsc_khz before configuring Hyper-V CPUID i386/kvm: introduce tsc_is_stable_and_known() i386/kvm: advertise Hyper-V frequency MSRs target/i386/kvm.c | 138 ++++++++++++++++++++++++++++-------------------------- 1 file changed, 71 insertions(+), 67 deletions(-) -- 2.9.3
