linux-kernel - Re: [PATCH v2 05/16] KVM: VMX: Drop initialization of IA32_FEATURE

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Message-ID: <20191025163958.GG6483@zn.tnic>
Date:   Fri, 25 Oct 2019 18:39:58 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>, kvm@...r.kernel.org
Subject: Re: [PATCH v2 05/16] KVM: VMX: Drop initialization of
 IA32_FEATURE_CONTROL MSR

On Fri, Oct 25, 2019 at 06:26:45PM +0200, Borislav Petkov wrote:
> On Mon, Oct 21, 2019 at 05:08:20PM -0700, Sean Christopherson wrote:
> > +	if (WARN_ON_ONCE(!(msr & FEATURE_CONTROL_LOCKED)))
> > +		return 1;
> > +
> > +	/* launched w/ TXT and VMX disabled */
> > +	if (!(msr & FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX) &&
> > +	    tboot_enabled())
> > +		return 1;
> > +	/* launched w/o TXT and VMX only enabled w/ TXT */
> > +	if (!(msr & FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX) &&
> > +	    (msr & FEATURE_CONTROL_VMXON_ENABLED_INSIDE_SMX) &&
> > +	    !tboot_enabled()) {
> > +		pr_warn("kvm: disable TXT in the BIOS or "
> > +			"activate TXT before enabling KVM\n");
> > +		return 1;
> 
> Might as well fix that with a cleanup patch ontop:
> 
> WARNING: quoted string split across lines
> #69: FILE: arch/x86/kvm/vmx/vmx.c:2208:
> +               pr_warn("kvm: disable TXT in the BIOS or "
> +                       "activate TXT before enabling KVM\n");
> 
> 
> Also in that same cleanup patch, if the order of those tests doesn't
> matter, you can simplify them a bit:
> 
> 	if (tboot_enabled()) {
> 		/* msr flag test here */
> 
> 	/* tboot disabled */
> 	} else {
> 		/* other two tests here */
> 	}
> 
> Should make it a bit easier to parse.

Nevermind - just saw patch 7. :)

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette