From: Marc Zyngier <maz@kernel.org>
To: Jianyong Wu <jianyong.wu@arm.com>
Cc: netdev@vger.kernel.org, yangbo.lu@nxp.com,
john.stultz@linaro.org, tglx@linutronix.de, pbonzini@redhat.com,
sean.j.christopherson@intel.com, richardcochran@gmail.com,
Mark.Rutland@arm.com, will@kernel.org, suzuki.poulose@arm.com,
steven.price@arm.com, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
Steve.Capper@arm.com, justin.he@arm.com, nd@arm.com
Subject: Re: [PATCH v14 08/10] ptp: arm64: Enable ptp_kvm for arm64
Date: Sun, 06 Sep 2020 11:00:37 +0100 [thread overview]
Message-ID: <87363vmdh6.wl-maz@kernel.org> (raw)
In-Reply-To: <874kocmqqx.wl-maz@kernel.org>
On Sat, 05 Sep 2020 12:01:42 +0100,
Marc Zyngier <maz@kernel.org> wrote:
>
> On Fri, 04 Sep 2020 10:27:42 +0100,
> Jianyong Wu <jianyong.wu@arm.com> wrote:
[...]
> > +{
> > + ktime_t ktime;
> > +
> > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID,
> > + hvc_res);
> > + if ((long long)(hvc_res->a0) < 0)
> > + return -EOPNOTSUPP;
>
> Really? What if the cycle counter is a full 64 bit value, as it is
> *mandated* on ARMv8.6? It means that the counter is now invalid for
> half the lifetime of the system. Not acceptable either.
Having re-read this, this field doesn't contain the cycle counter, but
the time in ns. So checking for a negative value should actually be
fine for quite a while. My other comments still stand though.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2020-09-06 10:00 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 9:27 [PATCH v14 00/10] Enable ptp_kvm for arm64 Jianyong Wu
2020-09-04 9:27 ` [PATCH v14 01/10] arm64: Probe for the presence of KVM hypervisor services during boot Jianyong Wu
2020-09-04 9:27 ` [PATCH v14 02/10] arm/arm64: KVM: Advertise KVM UID to guests via SMCCC Jianyong Wu
2020-09-04 9:27 ` [PATCH v14 03/10] smccc: Export smccc conduit get helper Jianyong Wu
2020-09-04 9:27 ` [PATCH v14 04/10] ptp: Reorganize ptp_kvm module to make it arch-independent Jianyong Wu
2020-09-04 9:27 ` [PATCH v14 05/10] time: Add mechanism to recognize clocksource in time_get_snapshot Jianyong Wu
2020-09-04 9:27 ` [PATCH v14 06/10] clocksource: Add clocksource id for arm arch counter Jianyong Wu
2020-09-04 9:27 ` [PATCH v14 07/10] arm64/kvm: Add hypercall service for kvm ptp Jianyong Wu
2020-09-04 16:15 ` Marc Zyngier
2020-09-07 8:10 ` Jianyong Wu
2020-09-05 11:04 ` Marc Zyngier
2020-09-07 8:13 ` Jianyong Wu
2020-09-04 9:27 ` [PATCH v14 08/10] ptp: arm64: Enable ptp_kvm for arm64 Jianyong Wu
2020-09-05 11:01 ` Marc Zyngier
2020-09-06 10:00 ` Marc Zyngier [this message]
2020-09-07 8:40 ` Jianyong Wu
2020-09-07 8:54 ` Marc Zyngier
2020-09-07 9:28 ` Jianyong Wu
2020-09-07 9:47 ` Marc Zyngier
2020-09-07 10:11 ` Jianyong Wu
2020-09-05 11:33 ` Marc Zyngier
2020-09-07 8:51 ` Jianyong Wu
2020-09-04 9:27 ` [PATCH v14 09/10] doc: add ptp_kvm introduction for arm64 support Jianyong Wu
2020-09-04 16:18 ` Marc Zyngier
2020-09-07 7:55 ` Jianyong Wu
2020-09-04 9:27 ` [PATCH v14 10/10] arm64: Add kvm capability check extension for ptp_kvm Jianyong Wu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87363vmdh6.wl-maz@kernel.org \
--to=maz@kernel.org \
--cc=Mark.Rutland@arm.com \
--cc=Steve.Capper@arm.com \
--cc=jianyong.wu@arm.com \
--cc=john.stultz@linaro.org \
--cc=justin.he@arm.com \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=nd@arm.com \
--cc=netdev@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=richardcochran@gmail.com \
--cc=sean.j.christopherson@intel.com \
--cc=steven.price@arm.com \
--cc=suzuki.poulose@arm.com \
--cc=tglx@linutronix.de \
--cc=will@kernel.org \
--cc=yangbo.lu@nxp.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).