On 01/22/2016 02:53 PM, Paolo Bonzini wrote:
On 22/01/2016 12:31, Andrey Smetanin wrote:
Sometimes the TSC is detected to be unstable and Linux switches to
another clocksource. At least in that case you can get a write to the
TSC page while the guest is running.
Sorry, now I got it, you mean host TSC is unstable and we should mark
guest tsc page invalid. Now I understand please ignore my prev. message.
No problem. Anyhow yes, this is what I meant: a host write to the TSC
page, not a guest write to the TSC page MSR.
Usually it happens only at migration time to update the sequence---which
I believe your patch wasn't doing either.
QEMU saves address of page inside ->msr_hv_tsc, so at restore
QEMU sets corresponding MSR and KVM setup's tsc page again.
So migration should able to work.
But if we tie TSC page
updates to kvm_gen_update_masterclock, we get that for free when the
migration destination calls the KVM_SET_CLOCK ioctl.
Paolo
