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From:   Michael Kelley <mikelley@microsoft.com>
To:     Vineeth Pillai <viremana@linux.microsoft.com>,
        Tianyu Lan <Tianyu.Lan@microsoft.com>,
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        Haiyang Zhang <haiyangz@microsoft.com>
CC:     "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
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Subject: RE: [PATCH 1/7] hyperv: Detect Nested virtualization support for SVM
Thread-Topic: [PATCH 1/7] hyperv: Detect Nested virtualization support for SVM
Thread-Index: AQHXK7whxv0u/iBNREG0GmXfpyQUWaqpd0gQ
Date:   Wed, 7 Apr 2021 19:55:15 +0000
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From: Vineeth Pillai <viremana@linux.microsoft.com> Sent: Wednesday, April =
7, 2021 7:41 AM
>=20
> Detect nested features exposed by Hyper-V if SVM is enabled.
>=20
> Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com>
> ---
>  arch/x86/kernel/cpu/mshyperv.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>=20
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyper=
v.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);
>  	}
>=20
> -	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 =3D
>  			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. :-)

> +			ms_hyperv.nested_features);
>  	}
>=20
>  	/*
> --
> 2.25.1