Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH v2 1/3] KVM: x86: implement KVM_{GET|SET}_TSC_STATE | Date | Tue, 08 Dec 2020 22:35:27 +0100 |
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On Tue, Dec 08 2020 at 15:12, Marcelo Tosatti wrote: > On Tue, Dec 08, 2020 at 06:25:13PM +0200, Maxim Levitsky wrote: >> On Tue, 2020-12-08 at 17:02 +0100, Thomas Gleixner wrote: >> The "bug" is that if VMM moves a hardware time counter (tsc or anything else) >> forward by large enough value in one go, >> then the guest kernel will supposingly have an overflow in the time code. >> I don't consider this to be a buggy VMM behavior, but rather a kernel >> bug that should be fixed (if this bug actually exists) > > It exists.
In the VMM.
>> We are talking about the fact that TSC can jump forward by arbitrary large >> value if the migration took arbitrary amount of time, which >> (assuming that the bug is real) can crash the guest kernel. > > QE reproduced it.
Sure, that's what QE is about. Just your conclusion is wrong.
Thanks,
tglx
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