linux-kernel - Re: [PATCH 1/2] KVM: x86: implement KVM_SET_TSC_PRECISE/KVM_GET_TSC

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Message-ID: <87h7p5fh1m.fsf@nanos.tec.linutronix.de>
Date:   Tue, 01 Dec 2020 20:43:49 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Maxim Levitsky <mlevitsk@...hat.com>, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Oliver Upton <oupton@...gle.com>,
        Ingo Molnar <mingo@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        open list <linux-kernel@...r.kernel.org>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>,
        Jim Mattson <jmattson@...gle.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "open list\:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        "maintainer\:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)" <x86@...nel.org>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: Re: [PATCH 1/2] KVM: x86: implement KVM_SET_TSC_PRECISE/KVM_GET_TSC_PRECISE

On Mon, Nov 30 2020 at 15:35, Maxim Levitsky wrote:
> +  struct kvm_tsc_info {
> +	__u32 flags;
> +	__u64 nsec;
> +	__u64 tsc;
> +	__u64 tsc_adjust;
> +  };
> +
> +flags values for ``struct kvm_tsc_info``:
> +
> +``KVM_TSC_INFO_TSC_ADJUST_VALID``
> +
> +  ``tsc_adjust`` contains valid IA32_TSC_ADJUST value

Why exposing TSC_ADJUST at all? Just because?

Thanks,

        tglx