linux-kernel - RE: [PATCH v14 07/10] arm64/kvm: Add hypercall service for kvm ptp.

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Date:   Mon, 7 Sep 2020 08:13:11 +0000
From:   Jianyong Wu <Jianyong.Wu@....com>
To:     Marc Zyngier <maz@...nel.org>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "yangbo.lu@....com" <yangbo.lu@....com>,
        "john.stultz@...aro.org" <john.stultz@...aro.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "sean.j.christopherson@...el.com" <sean.j.christopherson@...el.com>,
        "richardcochran@...il.com" <richardcochran@...il.com>,
        Mark Rutland <Mark.Rutland@....com>,
        "will@...nel.org" <will@...nel.org>,
        Suzuki Poulose <Suzuki.Poulose@....com>,
        Steven Price <Steven.Price@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "kvmarm@...ts.cs.columbia.edu" <kvmarm@...ts.cs.columbia.edu>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        Steve Capper <Steve.Capper@....com>,
        Justin He <Justin.He@....com>, nd <nd@....com>
Subject: RE: [PATCH v14 07/10] arm64/kvm: Add hypercall service for kvm ptp.

Hi Marc,

> -----Original Message-----
> From: Marc Zyngier <maz@...nel.org>
> Sent: Saturday, September 5, 2020 7:04 PM
> To: Jianyong Wu <Jianyong.Wu@....com>
> Cc: netdev@...r.kernel.org; yangbo.lu@....com; john.stultz@...aro.org;
> tglx@...utronix.de; pbonzini@...hat.com; sean.j.christopherson@...el.com;
> richardcochran@...il.com; Mark Rutland <Mark.Rutland@....com>;
> will@...nel.org; Suzuki Poulose <Suzuki.Poulose@....com>; Steven Price
> <Steven.Price@....com>; linux-kernel@...r.kernel.org; linux-arm-
> kernel@...ts.infradead.org; kvmarm@...ts.cs.columbia.edu;
> kvm@...r.kernel.org; Steve Capper <Steve.Capper@....com>; Justin He
> <Justin.He@....com>; nd <nd@....com>
> Subject: Re: [PATCH v14 07/10] arm64/kvm: Add hypercall service for kvm
> ptp.
> 
> On Fri, 04 Sep 2020 10:27:41 +0100,
> Jianyong Wu <jianyong.wu@....com> wrote:
> >
> > ptp_kvm will get this service through smccc call.
> > The service offers wall time and counter cycle of host for guest.
> > caller must explicitly determines which cycle of virtual counter or
> > physical counter to return if it needs counter cycle.
> >
> > Signed-off-by: Jianyong Wu <jianyong.wu@....com>
> > ---
> >  arch/arm64/kvm/Kconfig       |  6 +++++
> >  arch/arm64/kvm/arch_timer.c  |  2 +-
> >  arch/arm64/kvm/hypercalls.c  | 49
> > ++++++++++++++++++++++++++++++++++++
> >  include/kvm/arm_arch_timer.h |  1 +
> >  include/linux/arm-smccc.h    | 16 ++++++++++++
> >  5 files changed, 73 insertions(+), 1 deletion(-)
> >
> 
> [...]
> 
> On top of what I said yesterday:
> 
> > index 32ba6fbc3814..eb85f6701845 100644
> > --- a/arch/arm64/kvm/arch_timer.c
> > +++ b/arch/arm64/kvm/arch_timer.c
> > @@ -81,7 +81,7 @@ u64 timer_get_cval(struct arch_timer_context *ctxt)
> >  	}
> >  }
> >
> > -static u64 timer_get_offset(struct arch_timer_context *ctxt)
> > +u64 timer_get_offset(struct arch_timer_context *ctxt)
> >  {
> >  	struct kvm_vcpu *vcpu = ctxt->vcpu;
> >
> 
> Why has this become global? I can't see a reason why we would want to
> expose this purely KVM internal helper.
> 
Sorry to have forgotten remove this change.

Thanks
Jianyong 
> 	M.
> 
> --
> Without deviation from the norm, progress is not possible.