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Subject: Re: [RFC PATCH v3 4/6] psci: Add hvc call service for ptp_kvm.
To:     Jianyong Wu <jianyong.wu@arm.com>, netdev@vger.kernel.org,
        yangbo.lu@nxp.com, john.stultz@linaro.org, tglx@linutronix.de,
        sean.j.christopherson@intel.com, maz@kernel.org,
        richardcochran@gmail.com, Mark.Rutland@arm.com,
        Will.Deacon@arm.com, suzuki.poulose@arm.com
Cc:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        Steve.Capper@arm.com, Kaly.Xin@arm.com, justin.he@arm.com,
        nd@arm.com, linux-arm-kernel@lists.infradead.org
References: <20190918080716.64242-1-jianyong.wu@arm.com>
 <20190918080716.64242-5-jianyong.wu@arm.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
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Date:   Wed, 18 Sep 2019 10:25:37 +0200
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On 18/09/19 10:07, Jianyong Wu wrote:
> +=09case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
> +=09=09getnstimeofday(ts);

This is not Y2038-safe.  Please use ktime_get_real_ts64 instead, and
split the 64-bit seconds value between val[0] and val[1].

However, it seems to me that the new function is not needed and you can
just use ktime_get_snapshot.  You'll get the time in
systime_snapshot->real and the cycles value in systime_snapshot->cycles.

> +=09=09get_current_counterval(&sc);
> +=09=09val[0] =3D ts->tv_sec;
> +=09=09val[1] =3D ts->tv_nsec;
> +=09=09val[2] =3D sc.cycles;
> +=09=09val[3] =3D 0;
> +=09=09break;

This should return a guest-cycles value.  If the cycles values always
the same between the host and the guest on ARM, then okay.  If not, you
have to apply whatever offset exists.

Thanks,

Paolo