linux-kernel - Re: [PATCH 1/7] hyperv: Detect Nested virtualization support for SVM

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Message-ID: <YG42zNYA9uCC25In@google.com>
Date:   Wed, 7 Apr 2021 22:48:44 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Michael Kelley <mikelley@...rosoft.com>
Cc:     Vineeth Pillai <viremana@...ux.microsoft.com>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        vkuznets <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, Wei Liu <wei.liu@...nel.org>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        KY Srinivasan <kys@...rosoft.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>
Subject: Re: [PATCH 1/7] hyperv: Detect Nested virtualization support for SVM

On Wed, Apr 07, 2021, Michael Kelley wrote:
> From: Vineeth Pillai <viremana@...ux.microsoft.com> Sent: Wednesday, April 7, 2021 7:41 AM
> > 
> > Detect nested features exposed by Hyper-V if SVM is enabled.
> > 
> > Signed-off-by: Vineeth Pillai <viremana@...ux.microsoft.com>
> > ---
> >  arch/x86/kernel/cpu/mshyperv.c | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> > index 3546d3e21787..4d364acfe95d 100644
> > --- a/arch/x86/kernel/cpu/mshyperv.c
> > +++ b/arch/x86/kernel/cpu/mshyperv.c
> > @@ -325,9 +325,17 @@ static void __init ms_hyperv_init_platform(void)
> >  			ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
> >  	}
> > 
> > -	if (ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) {
> > +	/*
> > +	 * AMD does not need enlightened VMCS as VMCB is already a
> > +	 * datastructure in memory. We need to get the nested
> > +	 * features if SVM is enabled.
> > +	 */
> > +	if (boot_cpu_has(X86_FEATURE_SVM) ||
> > +	    ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) {
> >  		ms_hyperv.nested_features =
> >  			cpuid_eax(HYPERV_CPUID_NESTED_FEATURES);
> > +		pr_info("Hyper-V nested_features: 0x%x\n",
> 
> Nit:  Most other similar lines put the colon in a different place:
> 
> 		pr_info("Hyper-V: nested features 0x%x\n",
> 
> One of these days, I'm going to fix the ones that don't follow this
> pattern. :-)

Any reason not to use pr_fmt?