linux-kernel - Re: [PATCH v5 13/19] x86/cpufeatures: Add flag to track whether MSR IA32_FEAT

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Date:   Tue, 25 Feb 2020 16:58:40 -0800
From:   Jacob Keller <jacob.e.keller@...el.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     TonyWWang-oc@...oxin.com, acme@...nel.org,
        alexander.shishkin@...ux.intel.com, bp@...en8.de, bp@...e.de,
        hpa@...or.com, jacob.jun.pan@...ux.intel.com,
        jarkko.sakkinen@...ux.intel.com, jmattson@...gle.com,
        jolsa@...hat.com, joro@...tes.org, kvm@...r.kernel.org,
        lenb@...nel.org, linux-edac@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-pm@...r.kernel.org, mark.rutland@....com, mingo@...hat.com,
        namhyung@...nel.org, pbonzini@...hat.com, peterz@...radead.org,
        rkrcmar@...hat.com, shuah@...nel.org, tglx@...utronix.de,
        tony.luck@...el.com, vkuznets@...hat.com, wanpengli@...cent.com,
        x86@...nel.org
Subject: Re: [PATCH v5 13/19] x86/cpufeatures: Add flag to track whether MSR
 IA32_FEAT_CTL is configured

On 2/25/2020 4:42 PM, Sean Christopherson wrote>> So there's something
weird going on. Maybe "boot_cpu_has" in the
>> vmx_disabled_by_bios is wrong? Hmm.
> 
> Hmm, perhaps a bug somewhere else is overwriting the cpufeatures bit for
> X86_FEATURE_VMX.  Let me see if I can reproduce from net-next.
> 

If you have any further suggestions for debugging, I'm happy to help try
to figure this out. To my eyes, it looks like somehow bits get reset...
It's definitely not clear to me how this happens.

There is the get_cpu_caps call.. but that seems to correctly call
apply_forced_caps at the end.

That's all I have time for today.

Thanks,
Jake