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Oliver Upton
c68dc1b577
Handling the migration of TSCs correctly is difficult, in part because Linux does not provide userspace with the ability to retrieve a (TSC, realtime) clock pair for a single instant in time. In lieu of a more convenient facility, KVM can report similar information in the kvm_clock structure. Provide userspace with a host TSC & realtime pair iff the realtime clock is based on the TSC. If userspace provides KVM_SET_CLOCK with a valid realtime value, advance the KVM clock by the amount of elapsed time. Do not step the KVM clock backwards, though, as it is a monotonic oscillator. Suggested-by: Paolo Bonzini <[email protected]> Signed-off-by: Oliver Upton <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]> Message-Id: <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>