Re: [PATCH] KVM: VMX: enable LBR virtualization

[Jian Zhou]

> > > Does it depend on vPMU _for Linux guests_ or in general?  My impression
> > > is that LBR can be used by the guest independent of the PMU.
> >
> >    I think only for Linux guests.
> >
> >    I googled how to enable LBR on other guests(except Linux guests),
> >    e.g. Windows, and got no developer manuals about it.
> >
> >    Here is an article about it:
> >    http://www.codeproject.com/Articles/517466/Last-branch-records-
> >    and-branch-tracing
> >    it says:
> >    "bit 8 of DR7 represents bit 0 of DebugCtl. This is the LBR bit."
>
> Don't worry about the operating system in the guest: you are just
> emulating a processor feature, you do not care about anything except
> what is written in the Intel SDM.
>
> You can use kvm-unit-tests
> (https://git.kernel.org/cgit/virt/kvm/kvm-unit-tests.git/) to write a
> test for your feature.  There are existing tests for debugging features.

  ok.

  Regards,

  Jian

>

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