linux-kernel - Re: [PATCH] KVM: nVMX: Don't expose TSC scaling to L1 when on Hyper-V

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Message-ID: <75bdc7ee-bac5-ae05-dffb-cb749c9005e1@redhat.com>
Date:   Tue, 14 Jun 2022 14:16:00 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Anirudh Rayabharam <anrayabh@...ux.microsoft.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Ilias Stamatis <ilstam@...zon.com>,
        Maxim Levitsky <mlevitsk@...hat.com>, mail@...rudhrb.com,
        kumarpraveen@...ux.microsoft.com, wei.liu@...nel.org,
        robert.bradford@...el.com, liuwe@...rosoft.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: nVMX: Don't expose TSC scaling to L1 when on Hyper-V

On 6/14/22 06:55, Anirudh Rayabharam wrote:
>> That said, I think a better implementation of this patch is to just add
>> a version of evmcs_sanitize_exec_ctrls that takes a struct
>> nested_vmx_msrs *, and call it at the end of nested_vmx_setup_ctl_msrs like
>>
>> 	evmcs_sanitize_nested_vmx_vsrs(msrs);
> Sanitize at the end might not work because I see some cases in
> nested_vmx_setup_ctls_msrs() where we want to expose some things to L1
> even though the hardware doesn't support it.
> 

Yes, but these will never include eVMCS-unsupported features.

Paolo