linux-kernel - Re: [PATCH v7 7/7] KVM: x86: Add user-space access interface for CET MSRs

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Date:   Thu, 17 Oct 2019 12:58:11 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Jim Mattson <jmattson@...gle.com>
Cc:     Yang Weijiang <weijiang.yang@...el.com>,
        kvm list <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: Re: [PATCH v7 7/7] KVM: x86: Add user-space access interface for CET
 MSRs

On Wed, Oct 02, 2019 at 01:57:50PM -0700, Jim Mattson wrote:
> On Thu, Sep 26, 2019 at 7:17 PM Yang Weijiang <weijiang.yang@...el.com> wrote:
> >
> > There're two different places storing Guest CET states, the states
> > managed with XSAVES/XRSTORS, as restored/saved
> > in previous patch, can be read/write directly from/to the MSRs.
> > For those stored in VMCS fields, they're access via vmcs_read/
> > vmcs_write.
> >
> > Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
> > ---
> >  arch/x86/kvm/vmx/vmx.c | 83 ++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 83 insertions(+)
> >
> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > index 44913e4ab558..5265db7cd2af 100644
> > --- a/arch/x86/kvm/vmx/vmx.c
> > +++ b/arch/x86/kvm/vmx/vmx.c
> > @@ -1671,6 +1671,49 @@ static int vmx_get_msr_feature(struct kvm_msr_entry *msr)
> >         return 0;
> >  }
> >
> > +static int check_cet_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> 
> I'd suggest changing return type to bool, since you are essentially
> returning true or false.

I'd also be more explicit in the name, e.g. is_valid_cet_msr().