On Mon, Aug 16, 2021 at 12:11:27AM +0000, Oliver Upton wrote: > 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 <pbonzini@xxxxxxxxxx> > Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx> This is a good idea. Userspace could check if host and destination clocks are up to a certain difference and not use the feature if not appropriate. Is there a qemu patch for it?
