On Thu, Jun 20, 2013 at 08:29:30PM +0100, Peter Maydell wrote: > On 20 June 2013 19:32, Christoffer Dall <christoffer.dall@xxxxxxxxxx> wrote: > > Marc wrote: > >> So there is just one thing we absolutely need to make sure here: no vcpu > >> can run before they've all had their timer restored, and hence a stable > >> cntvoff. Otherwise two vcpus will have a different view of time. > >> > >> Can we guarantee this? > > > Do we need to? User space is free to modify time and all sort of other > > registers at any point during VM execution - it will just break the > > guest that it's running. > > Note that QEMU will stop all CPUs before doing a migration or > similar operation. However there is a monitor command to query > the current CPU registers etc which won't try to stop the VM > first. So we might try to read vcpu registers (though I hope we > don't allow writing them). > Sounds like we need to add a -EBUSY return on SET_ONE_REG if the VM is running. -Christoffer _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
