From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7253CC2D0E4 for ; Mon, 23 Nov 2020 10:49:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0BA4B207FF for ; Mon, 23 Nov 2020 10:49:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="GZiTm1ui" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728796AbgKWKt2 (ORCPT ); Mon, 23 Nov 2020 05:49:28 -0500 Received: from mail.kernel.org ([198.145.29.99]:42170 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728523AbgKWKt1 (ORCPT ); Mon, 23 Nov 2020 05:49:27 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5E85F20721; Mon, 23 Nov 2020 10:49:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606128565; bh=FVXXoRtxeNSHeXC+MN7Fmb60y4SrrZ1lu3dPmXQA4V0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=GZiTm1uizupDL2CKQ2nO6GOQBW7NrtZuOYT8myiVKZU4qg1AtN46rvO47OtuhmkFu 4ViSzyeuCTau501Xr3H/6oArwCEOIDsSLeGKEhubGdrq2G0AM0Q1+YvQDdrLAOzwjG 9oc8TcdPJYxO5j6fEZ2iZFKl2girgr8TzfWmNqb8= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1kh9PP-00Ct2d-3n; Mon, 23 Nov 2020 10:49:23 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 23 Nov 2020 10:49:23 +0000 From: Marc Zyngier To: Jianyong Wu 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, Andre.Przywara@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 v15 7/9] ptp: arm/arm64: Enable ptp_kvm for arm/arm64 In-Reply-To: <20201111062211.33144-8-jianyong.wu@arm.com> References: <20201111062211.33144-1-jianyong.wu@arm.com> <20201111062211.33144-8-jianyong.wu@arm.com> User-Agent: Roundcube Webmail/1.4.9 Message-ID: <7bd3a66253ca4b7adbe2294eb598a23f@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: jianyong.wu@arm.com, 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, Andre.Przywara@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 X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-11-11 06:22, Jianyong Wu wrote: > Currently, there is no mechanism to keep time sync between guest and > host > in arm/arm64 virtualization environment. Time in guest will drift > compared > with host after boot up as they may both use third party time sources > to correct their time respectively. The time deviation will be in order > of milliseconds. But in some scenarios,like in cloud envirenment, we > ask environment > for higher time precision. > > kvm ptp clock, which chooses the host clock source as a reference > clock to sync time between guest and host, has been adopted by x86 > which takes the time sync order from milliseconds to nanoseconds. > > This patch enables kvm ptp clock for arm/arm64 and improves clock sync > precison precision > significantly. > > Test result comparisons between with kvm ptp clock and without it in > arm/arm64 > are as follows. This test derived from the result of command 'chronyc > sources'. we should take more care of the last sample column which > shows > the offset between the local clock and the source at the last > measurement. > > no kvm ptp in guest: > MS Name/IP address Stratum Poll Reach LastRx Last sample > ======================================================================== > ^* dns1.synet.edu.cn 2 6 377 13 +1040us[+1581us] +/- > 21ms > ^* dns1.synet.edu.cn 2 6 377 21 +1040us[+1581us] +/- > 21ms > ^* dns1.synet.edu.cn 2 6 377 29 +1040us[+1581us] +/- > 21ms > ^* dns1.synet.edu.cn 2 6 377 37 +1040us[+1581us] +/- > 21ms > ^* dns1.synet.edu.cn 2 6 377 45 +1040us[+1581us] +/- > 21ms > ^* dns1.synet.edu.cn 2 6 377 53 +1040us[+1581us] +/- > 21ms > ^* dns1.synet.edu.cn 2 6 377 61 +1040us[+1581us] +/- > 21ms > ^* dns1.synet.edu.cn 2 6 377 4 -130us[ +796us] +/- > 21ms > ^* dns1.synet.edu.cn 2 6 377 12 -130us[ +796us] +/- > 21ms > ^* dns1.synet.edu.cn 2 6 377 20 -130us[ +796us] +/- > 21ms > > in host: > MS Name/IP address Stratum Poll Reach LastRx Last sample > ======================================================================== > ^* 120.25.115.20 2 7 377 72 -470us[ -603us] +/- > 18ms > ^* 120.25.115.20 2 7 377 92 -470us[ -603us] +/- > 18ms > ^* 120.25.115.20 2 7 377 112 -470us[ -603us] +/- > 18ms > ^* 120.25.115.20 2 7 377 2 +872ns[-6808ns] +/- > 17ms > ^* 120.25.115.20 2 7 377 22 +872ns[-6808ns] +/- > 17ms > ^* 120.25.115.20 2 7 377 43 +872ns[-6808ns] +/- > 17ms > ^* 120.25.115.20 2 7 377 63 +872ns[-6808ns] +/- > 17ms > ^* 120.25.115.20 2 7 377 83 +872ns[-6808ns] +/- > 17ms > ^* 120.25.115.20 2 7 377 103 +872ns[-6808ns] +/- > 17ms > ^* 120.25.115.20 2 7 377 123 +872ns[-6808ns] +/- > 17ms > > The dns1.synet.edu.cn is the network reference clock for guest and > 120.25.115.20 is the network reference clock for host. we can't get the > clock error between guest and host directly, but a roughly estimated > value > will be in order of hundreds of us to ms. > > with kvm ptp in guest: > chrony has been disabled in host to remove the disturb by network > clock. > > MS Name/IP address Stratum Poll Reach LastRx Last sample > ======================================================================== > * PHC0 0 3 377 8 -7ns[ +1ns] +/- > 3ns > * PHC0 0 3 377 8 +1ns[ +16ns] +/- > 3ns > * PHC0 0 3 377 6 -4ns[ -0ns] +/- > 6ns > * PHC0 0 3 377 6 -8ns[ -12ns] +/- > 5ns > * PHC0 0 3 377 5 +2ns[ +4ns] +/- > 4ns > * PHC0 0 3 377 13 +2ns[ +4ns] +/- > 4ns > * PHC0 0 3 377 12 -4ns[ -6ns] +/- > 4ns > * PHC0 0 3 377 11 -8ns[ -11ns] +/- > 6ns > * PHC0 0 3 377 10 -14ns[ -20ns] +/- > 4ns > * PHC0 0 3 377 8 +4ns[ +5ns] +/- > 4ns > > The PHC0 is the ptp clock which choose the host clock as its source > clock. So we can see that the clock difference between host and guest > is in order of ns. > > Signed-off-by: Jianyong Wu > --- > drivers/clocksource/arm_arch_timer.c | 28 ++++++++++++++++++ > drivers/ptp/Kconfig | 2 +- > drivers/ptp/Makefile | 1 + > drivers/ptp/ptp_kvm_arm.c | 44 ++++++++++++++++++++++++++++ > 4 files changed, 74 insertions(+), 1 deletion(-) > create mode 100644 drivers/ptp/ptp_kvm_arm.c > > diff --git a/drivers/clocksource/arm_arch_timer.c > b/drivers/clocksource/arm_arch_timer.c > index d55acffb0b90..b33c5a663d30 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -25,6 +25,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -1650,3 +1651,30 @@ static int __init arch_timer_acpi_init(struct > acpi_table_header *table) > } > TIMER_ACPI_DECLARE(arch_timer, ACPI_SIG_GTDT, arch_timer_acpi_init); > #endif > + > +int kvm_arch_ptp_get_crosststamp(u64 *cycle, struct timespec64 *ts, > + struct clocksource **cs) > +{ > + struct arm_smccc_res hvc_res; > + ktime_t ktime; > + u32 ptp_counter; > + > + if (arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) > + ptp_counter = ARM_PTP_VIRT_COUNTER; > + else > + ptp_counter = ARM_PTP_PHY_COUNTER; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, > + ptp_counter, &hvc_res); > + > + if ((int)(hvc_res.a0) < 0) > + return -EOPNOTSUPP; > + > + ktime = (u64)hvc_res.a0 << 32 | hvc_res.a1; > + *ts = ktime_to_timespec64(ktime); > + *cycle = (u64)hvc_res.a2 << 32 | hvc_res.a3; Endianness. > + *cs = &clocksource_counter; > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(kvm_arch_ptp_get_crosststamp); > diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig > index 942f72d8151d..677c7f696b70 100644 > --- a/drivers/ptp/Kconfig > +++ b/drivers/ptp/Kconfig > @@ -106,7 +106,7 @@ config PTP_1588_CLOCK_PCH > config PTP_1588_CLOCK_KVM > tristate "KVM virtual PTP clock" > depends on PTP_1588_CLOCK > - depends on KVM_GUEST && X86 > + depends on KVM_GUEST && X86 || (HAVE_ARM_SMCCC_DISCOVERY && > ARM_ARCH_TIMER) > default y > help > This driver adds support for using kvm infrastructure as a PTP > diff --git a/drivers/ptp/Makefile b/drivers/ptp/Makefile > index 699a4e4d19c2..9fa5ede44b2b 100644 > --- a/drivers/ptp/Makefile > +++ b/drivers/ptp/Makefile > @@ -5,6 +5,7 @@ > > ptp-y := ptp_clock.o ptp_chardev.o ptp_sysfs.o > ptp_kvm-$(CONFIG_X86) := ptp_kvm_x86.o ptp_kvm_common.o > +ptp_kvm-$(CONFIG_HAVE_ARM_SMCCC) := ptp_kvm_arm.o ptp_kvm_common.o > obj-$(CONFIG_PTP_1588_CLOCK) += ptp.o > obj-$(CONFIG_PTP_1588_CLOCK_DTE) += ptp_dte.o > obj-$(CONFIG_PTP_1588_CLOCK_INES) += ptp_ines.o > diff --git a/drivers/ptp/ptp_kvm_arm.c b/drivers/ptp/ptp_kvm_arm.c > new file mode 100644 > index 000000000000..2212827c0384 > --- /dev/null > +++ b/drivers/ptp/ptp_kvm_arm.c > @@ -0,0 +1,44 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Virtual PTP 1588 clock for use with KVM guests > + * Copyright (C) 2019 ARM Ltd. > + * All Rights Reserved > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +int kvm_arch_ptp_init(void) > +{ > + int ret; > + > + ret = kvm_arm_hyp_service_available(ARM_SMCCC_KVM_FUNC_KVM_PTP); > + if (ret <= 0) > + return -EOPNOTSUPP; > + > + return 0; > +} > + > +int kvm_arch_ptp_get_clock(struct timespec64 *ts) > +{ > + ktime_t ktime; > + struct arm_smccc_res hvc_res; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, > + ARM_PTP_NONE_COUNTER, &hvc_res); I really don't see the need to use a non-architectural counter ID. Using the virtual counter ID should just be fine, and shouldn't lead to any issue. Am I missing something? > + if ((int)(hvc_res.a0) < 0) > + return -EOPNOTSUPP; > + > + ktime = (u64)hvc_res.a0 << 32 | hvc_res.a1; Endianness. > + *ts = ktime_to_timespec64(ktime); > + > + return 0; > +} Thanks, M. -- Jazz is not dead. It just smells funny...