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Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX

From Borislav Petkov <bp@alien8.de>
Newsgroups linux.kernel
Subject Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX
Date 2016-07-07 15:00 +0200
Message-ID <rSh4m-71b-49@gated-at.bofh.it> (permalink)
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On Thu, Jul 07, 2016 at 02:28:29PM +0200, Paolo Bonzini wrote:
> Because otherwise you couldn't do live migration from new QEMU + new
> kernel to new QEMU + old kernel.  QEMU tries to avoid requiring lockstep
> upgrades of QEMU and KVM (unlike for example perf).

Hmm, ok.

About that - and I've asked about it a couple of times already - how
would you guys feel about a testing feature to qemu - something I'd love
to have with which I can set arbitrary CPUID bits for testing kernels?

I.e., something like that:

qemu ... -cpu=Opteron_G5,cpuid_leaf=<bla>,eax=<..>,ebx=<...>, ...,filter=off

The filter=off thing is to disable the checking in
x86_cpu_filter_features() so that those arbitrary CPUID leafs are
actually simulated to the guest.

Would something like that make sense for upstream or should I hack it in
locally only?

Because it sure does help a lot when testing kernel features for
unreleased CPUs but for which the code is already being submitted. And
with a qemu feature like that, we could at least smoke-test those a bit.

Hmmm?

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.

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Thread

[PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Paolo Bonzini <pbonzini@redhat.com> - 2016-07-06 15:50 +0200
  Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Borislav Petkov <bp@alien8.de> - 2016-07-06 16:20 +0200
    Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Paolo Bonzini <pbonzini@redhat.com> - 2016-07-06 16:30 +0200
      Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Borislav Petkov <bp@alien8.de> - 2016-07-07 12:50 +0200
        Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Paolo Bonzini <pbonzini@redhat.com> - 2016-07-07 13:10 +0200
          Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Borislav Petkov <bp@alien8.de> - 2016-07-07 13:50 +0200
            Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Paolo Bonzini <pbonzini@redhat.com> - 2016-07-07 14:30 +0200
              Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Borislav Petkov <bp@alien8.de> - 2016-07-07 15:00 +0200
                Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Paolo Bonzini <pbonzini@redhat.com> - 2016-07-07 15:20 +0200
                Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Borislav Petkov <bp@alien8.de> - 2016-07-07 18:10 +0200
                Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Paolo Bonzini <pbonzini@redhat.com> - 2016-07-07 18:20 +0200
                Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Eduardo Habkost <ehabkost@redhat.com> - 2016-07-07 18:30 +0200
                Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Borislav Petkov <bp@alien8.de> - 2016-07-07 19:10 +0200
                Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Eduardo Habkost <ehabkost@redhat.com> - 2016-07-07 19:50 +0200
                Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Borislav Petkov <bp@alien8.de> - 2016-07-08 13:10 +0200
                Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Paolo Bonzini <pbonzini@redhat.com> - 2016-07-08 13:20 +0200
                Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX Borislav Petkov <bp@alien8.de> - 2016-07-08 15:00 +0200
  Re: [PATCH] KVM: SVM: fix trashing of MSR_TSC_AUX kbuild test robot <lkp@intel.com> - 2016-07-06 17:10 +0200

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