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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 4ADFCC33C99 for ; Tue, 7 Jan 2020 09:29:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 03560206DB for ; Tue, 7 Jan 2020 09:29:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578389374; bh=EzepXcOh6NNd+CModDYitbngAr5w/T80SpUwJ7cBNS8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=vxVsgW++t4CdHdhEBD6uApKGAYYSxzV83IUTA/lQltuevDTxCHfv/im99Ef10l84A dAzp5keUHIfP2ePk1zwfr+e1KlKcHr956jnBao7S8YPP7alThZnlCxUcUl24Xyt8eD mOJgefFewawF5/sJaXgN2VHv87r6isIRYDBxaoAg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727745AbgAGJ3d (ORCPT ); Tue, 7 Jan 2020 04:29:33 -0500 Received: from mail.kernel.org ([198.145.29.99]:58446 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727616AbgAGJ3c (ORCPT ); Tue, 7 Jan 2020 04:29:32 -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 173BA2073D; Tue, 7 Jan 2020 09:29:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578389371; bh=EzepXcOh6NNd+CModDYitbngAr5w/T80SpUwJ7cBNS8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=am+oPwxfbwzq+wL8gwB7ktpHLYqN9T2T165OVDrwWX63EEHla0tcTBmmldG58hkdy fFMZ5jsJ4XJFWqzHD+/S4Zs14ojmHnNkq2kEQu2Oi0+ca0mJv3X1vJ7+2aM+mG+GhH XSTfyBAZZuOS29De993l+MuKeJyXlI1kpycDq5WI= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1iolB3-0000wX-EC; Tue, 07 Jan 2020 09:29:29 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 07 Jan 2020 09:29:29 +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, 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, Kaly.Xin@arm.com, justin.he@arm.com, nd@arm.com Subject: Re: [RFC PATCH v9 7/8] ptp: arm64: Enable ptp_kvm for arm64 In-Reply-To: <20191210034026.45229-8-jianyong.wu@arm.com> References: <20191210034026.45229-1-jianyong.wu@arm.com> <20191210034026.45229-8-jianyong.wu@arm.com> Message-ID: X-Sender: maz@kernel.org User-Agent: Roundcube Webmail/1.3.8 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, 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, Kaly.Xin@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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-12-10 03:40, Jianyong Wu wrote: > Currently in arm64 virtualization environment, there is no mechanism to > keep time sync between guest and host. 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 some scenarios ask for higher time precision, like > in cloud envirenment, we want all the VMs running in the host aquire > the > same level accuracy from host clock. > > Use of kvm ptp clock, which choose the host clock source clock as a > reference clock to sync time clock between guest and host has been > adopted > by x86 which makes the time sync order from milliseconds to > nanoseconds. > > This patch enable kvm ptp on arm64 and we get the similar clock drift > as > found with x86 with kvm ptp. > > Test result comparison between with kvm ptp and without it in arm64 are > as follows. This test derived from the result of command 'chronyc > sources'. we should take more cure 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 be sure to say that the clock error between host and > guest > is in order of ns. > > Signed-off-by: Jianyong Wu > --- > drivers/clocksource/arm_arch_timer.c | 22 ++++++++++++ > drivers/ptp/Kconfig | 2 +- > drivers/ptp/ptp_kvm_arm64.c | 53 ++++++++++++++++++++++++++++ > 3 files changed, 76 insertions(+), 1 deletion(-) > create mode 100644 drivers/ptp/ptp_kvm_arm64.c > > diff --git a/drivers/clocksource/arm_arch_timer.c > b/drivers/clocksource/arm_arch_timer.c > index 277846decd33..72260b66f02e 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -1636,3 +1636,25 @@ 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 > + > +#if IS_ENABLED(CONFIG_PTP_1588_CLOCK_KVM) > +#include > +int kvm_arch_ptp_get_crosststamp(unsigned long *cycle, struct > timespec64 *ts, > + struct clocksource **cs) > +{ > + struct arm_smccc_res hvc_res; > + ktime_t ktime_overall; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, &hvc_res); > + if ((long)(hvc_res.a0) < 0) > + return -EOPNOTSUPP; > + > + ktime_overall = hvc_res.a0 << 32 | hvc_res.a1; > + *ts = ktime_to_timespec64(ktime_overall); > + *cycle = hvc_res.a2 << 32 | hvc_res.a3; So why isn't that just a read of the virtual counter, given that what you do in the hypervisor seems to be "cntpct - cntvoff"? What am I missing here? > + *cs = &clocksource_counter; > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(kvm_arch_ptp_get_crosststamp); > +#endif > diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig > index 9b8fee5178e8..3c31ff8eb05f 100644 > --- a/drivers/ptp/Kconfig > +++ b/drivers/ptp/Kconfig > @@ -110,7 +110,7 @@ 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 || ARM64 && ARM_ARCH_TIMER > default y > help > This driver adds support for using kvm infrastructure as a PTP > diff --git a/drivers/ptp/ptp_kvm_arm64.c b/drivers/ptp/ptp_kvm_arm64.c > new file mode 100644 > index 000000000000..f3f957117865 > --- /dev/null > +++ b/drivers/ptp/ptp_kvm_arm64.c > @@ -0,0 +1,53 @@ > +// 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 > + > +int kvm_arch_ptp_init(void) > +{ > + struct arm_smccc_res hvc_res; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, > + &hvc_res); > + if ((long)(hvc_res.a0) < 0) > + return -EOPNOTSUPP; > + > + return 0; > +} > + > +int kvm_arch_ptp_get_clock_generic(struct timespec64 *ts, > + struct arm_smccc_res *hvc_res) > +{ > + ktime_t ktime_overall; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, > + hvc_res); > + if ((long)(hvc_res->a0) < 0) > + return -EOPNOTSUPP; > + > + ktime_overall = hvc_res->a0 << 32 | hvc_res->a1; > + *ts = ktime_to_timespec64(ktime_overall); > + > + return 0; > +} > + > +int kvm_arch_ptp_get_clock(struct timespec64 *ts) > +{ > + struct arm_smccc_res hvc_res; > + > + kvm_arch_ptp_get_clock_generic(ts, &hvc_res); > + > + return 0; > +} I also wonder why this is all arm64 specific, while everything should also work just fine on 32bit. M. -- Jazz is not dead. It just smells funny... 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Tue, 07 Jan 2020 09:29:29 +0000 MIME-Version: 1.0 Date: Tue, 07 Jan 2020 09:29:29 +0000 From: Marc Zyngier To: Jianyong Wu Subject: Re: [RFC PATCH v9 7/8] ptp: arm64: Enable ptp_kvm for arm64 In-Reply-To: <20191210034026.45229-8-jianyong.wu@arm.com> References: <20191210034026.45229-1-jianyong.wu@arm.com> <20191210034026.45229-8-jianyong.wu@arm.com> Message-ID: X-Sender: maz@kernel.org User-Agent: Roundcube Webmail/1.3.8 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, 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, Kaly.Xin@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 Cc: justin.he@arm.com, kvm@vger.kernel.org, netdev@vger.kernel.org, richardcochran@gmail.com, linux-kernel@vger.kernel.org, sean.j.christopherson@intel.com, steven.price@arm.com, john.stultz@linaro.org, yangbo.lu@nxp.com, pbonzini@redhat.com, tglx@linutronix.de, nd@arm.com, will@kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 2019-12-10 03:40, Jianyong Wu wrote: > Currently in arm64 virtualization environment, there is no mechanism to > keep time sync between guest and host. 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 some scenarios ask for higher time precision, like > in cloud envirenment, we want all the VMs running in the host aquire > the > same level accuracy from host clock. > > Use of kvm ptp clock, which choose the host clock source clock as a > reference clock to sync time clock between guest and host has been > adopted > by x86 which makes the time sync order from milliseconds to > nanoseconds. > > This patch enable kvm ptp on arm64 and we get the similar clock drift > as > found with x86 with kvm ptp. > > Test result comparison between with kvm ptp and without it in arm64 are > as follows. This test derived from the result of command 'chronyc > sources'. we should take more cure 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 be sure to say that the clock error between host and > guest > is in order of ns. > > Signed-off-by: Jianyong Wu > --- > drivers/clocksource/arm_arch_timer.c | 22 ++++++++++++ > drivers/ptp/Kconfig | 2 +- > drivers/ptp/ptp_kvm_arm64.c | 53 ++++++++++++++++++++++++++++ > 3 files changed, 76 insertions(+), 1 deletion(-) > create mode 100644 drivers/ptp/ptp_kvm_arm64.c > > diff --git a/drivers/clocksource/arm_arch_timer.c > b/drivers/clocksource/arm_arch_timer.c > index 277846decd33..72260b66f02e 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -1636,3 +1636,25 @@ 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 > + > +#if IS_ENABLED(CONFIG_PTP_1588_CLOCK_KVM) > +#include > +int kvm_arch_ptp_get_crosststamp(unsigned long *cycle, struct > timespec64 *ts, > + struct clocksource **cs) > +{ > + struct arm_smccc_res hvc_res; > + ktime_t ktime_overall; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, &hvc_res); > + if ((long)(hvc_res.a0) < 0) > + return -EOPNOTSUPP; > + > + ktime_overall = hvc_res.a0 << 32 | hvc_res.a1; > + *ts = ktime_to_timespec64(ktime_overall); > + *cycle = hvc_res.a2 << 32 | hvc_res.a3; So why isn't that just a read of the virtual counter, given that what you do in the hypervisor seems to be "cntpct - cntvoff"? What am I missing here? > + *cs = &clocksource_counter; > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(kvm_arch_ptp_get_crosststamp); > +#endif > diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig > index 9b8fee5178e8..3c31ff8eb05f 100644 > --- a/drivers/ptp/Kconfig > +++ b/drivers/ptp/Kconfig > @@ -110,7 +110,7 @@ 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 || ARM64 && ARM_ARCH_TIMER > default y > help > This driver adds support for using kvm infrastructure as a PTP > diff --git a/drivers/ptp/ptp_kvm_arm64.c b/drivers/ptp/ptp_kvm_arm64.c > new file mode 100644 > index 000000000000..f3f957117865 > --- /dev/null > +++ b/drivers/ptp/ptp_kvm_arm64.c > @@ -0,0 +1,53 @@ > +// 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 > + > +int kvm_arch_ptp_init(void) > +{ > + struct arm_smccc_res hvc_res; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, > + &hvc_res); > + if ((long)(hvc_res.a0) < 0) > + return -EOPNOTSUPP; > + > + return 0; > +} > + > +int kvm_arch_ptp_get_clock_generic(struct timespec64 *ts, > + struct arm_smccc_res *hvc_res) > +{ > + ktime_t ktime_overall; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, > + hvc_res); > + if ((long)(hvc_res->a0) < 0) > + return -EOPNOTSUPP; > + > + ktime_overall = hvc_res->a0 << 32 | hvc_res->a1; > + *ts = ktime_to_timespec64(ktime_overall); > + > + return 0; > +} > + > +int kvm_arch_ptp_get_clock(struct timespec64 *ts) > +{ > + struct arm_smccc_res hvc_res; > + > + kvm_arch_ptp_get_clock_generic(ts, &hvc_res); > + > + return 0; > +} I also wonder why this is all arm64 specific, while everything should also work just fine on 32bit. M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm 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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS 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 44C18C33CA1 for ; Tue, 7 Jan 2020 09:29:37 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1898820848 for ; Tue, 7 Jan 2020 09:29:37 +0000 (UTC) Authentication-Results: mail.kernel.org; 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Tue, 7 Jan 2020 09:29:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578389371; bh=EzepXcOh6NNd+CModDYitbngAr5w/T80SpUwJ7cBNS8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=am+oPwxfbwzq+wL8gwB7ktpHLYqN9T2T165OVDrwWX63EEHla0tcTBmmldG58hkdy fFMZ5jsJ4XJFWqzHD+/S4Zs14ojmHnNkq2kEQu2Oi0+ca0mJv3X1vJ7+2aM+mG+GhH XSTfyBAZZuOS29De993l+MuKeJyXlI1kpycDq5WI= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1iolB3-0000wX-EC; Tue, 07 Jan 2020 09:29:29 +0000 MIME-Version: 1.0 Date: Tue, 07 Jan 2020 09:29:29 +0000 From: Marc Zyngier To: Jianyong Wu Subject: Re: [RFC PATCH v9 7/8] ptp: arm64: Enable ptp_kvm for arm64 In-Reply-To: <20191210034026.45229-8-jianyong.wu@arm.com> References: <20191210034026.45229-1-jianyong.wu@arm.com> <20191210034026.45229-8-jianyong.wu@arm.com> Message-ID: X-Sender: maz@kernel.org User-Agent: Roundcube Webmail/1.3.8 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, 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, Kaly.Xin@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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200107_012931_736555_14901EB1 X-CRM114-Status: GOOD ( 29.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark.Rutland@arm.com, justin.he@arm.com, kvm@vger.kernel.org, suzuki.poulose@arm.com, netdev@vger.kernel.org, richardcochran@gmail.com, Steve.Capper@arm.com, linux-kernel@vger.kernel.org, sean.j.christopherson@intel.com, steven.price@arm.com, Kaly.Xin@arm.com, john.stultz@linaro.org, yangbo.lu@nxp.com, pbonzini@redhat.com, tglx@linutronix.de, nd@arm.com, will@kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2019-12-10 03:40, Jianyong Wu wrote: > Currently in arm64 virtualization environment, there is no mechanism to > keep time sync between guest and host. 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 some scenarios ask for higher time precision, like > in cloud envirenment, we want all the VMs running in the host aquire > the > same level accuracy from host clock. > > Use of kvm ptp clock, which choose the host clock source clock as a > reference clock to sync time clock between guest and host has been > adopted > by x86 which makes the time sync order from milliseconds to > nanoseconds. > > This patch enable kvm ptp on arm64 and we get the similar clock drift > as > found with x86 with kvm ptp. > > Test result comparison between with kvm ptp and without it in arm64 are > as follows. This test derived from the result of command 'chronyc > sources'. we should take more cure 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 be sure to say that the clock error between host and > guest > is in order of ns. > > Signed-off-by: Jianyong Wu > --- > drivers/clocksource/arm_arch_timer.c | 22 ++++++++++++ > drivers/ptp/Kconfig | 2 +- > drivers/ptp/ptp_kvm_arm64.c | 53 ++++++++++++++++++++++++++++ > 3 files changed, 76 insertions(+), 1 deletion(-) > create mode 100644 drivers/ptp/ptp_kvm_arm64.c > > diff --git a/drivers/clocksource/arm_arch_timer.c > b/drivers/clocksource/arm_arch_timer.c > index 277846decd33..72260b66f02e 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -1636,3 +1636,25 @@ 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 > + > +#if IS_ENABLED(CONFIG_PTP_1588_CLOCK_KVM) > +#include > +int kvm_arch_ptp_get_crosststamp(unsigned long *cycle, struct > timespec64 *ts, > + struct clocksource **cs) > +{ > + struct arm_smccc_res hvc_res; > + ktime_t ktime_overall; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, &hvc_res); > + if ((long)(hvc_res.a0) < 0) > + return -EOPNOTSUPP; > + > + ktime_overall = hvc_res.a0 << 32 | hvc_res.a1; > + *ts = ktime_to_timespec64(ktime_overall); > + *cycle = hvc_res.a2 << 32 | hvc_res.a3; So why isn't that just a read of the virtual counter, given that what you do in the hypervisor seems to be "cntpct - cntvoff"? What am I missing here? > + *cs = &clocksource_counter; > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(kvm_arch_ptp_get_crosststamp); > +#endif > diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig > index 9b8fee5178e8..3c31ff8eb05f 100644 > --- a/drivers/ptp/Kconfig > +++ b/drivers/ptp/Kconfig > @@ -110,7 +110,7 @@ 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 || ARM64 && ARM_ARCH_TIMER > default y > help > This driver adds support for using kvm infrastructure as a PTP > diff --git a/drivers/ptp/ptp_kvm_arm64.c b/drivers/ptp/ptp_kvm_arm64.c > new file mode 100644 > index 000000000000..f3f957117865 > --- /dev/null > +++ b/drivers/ptp/ptp_kvm_arm64.c > @@ -0,0 +1,53 @@ > +// 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 > + > +int kvm_arch_ptp_init(void) > +{ > + struct arm_smccc_res hvc_res; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, > + &hvc_res); > + if ((long)(hvc_res.a0) < 0) > + return -EOPNOTSUPP; > + > + return 0; > +} > + > +int kvm_arch_ptp_get_clock_generic(struct timespec64 *ts, > + struct arm_smccc_res *hvc_res) > +{ > + ktime_t ktime_overall; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, > + hvc_res); > + if ((long)(hvc_res->a0) < 0) > + return -EOPNOTSUPP; > + > + ktime_overall = hvc_res->a0 << 32 | hvc_res->a1; > + *ts = ktime_to_timespec64(ktime_overall); > + > + return 0; > +} > + > +int kvm_arch_ptp_get_clock(struct timespec64 *ts) > +{ > + struct arm_smccc_res hvc_res; > + > + kvm_arch_ptp_get_clock_generic(ts, &hvc_res); > + > + return 0; > +} I also wonder why this is all arm64 specific, while everything should also work just fine on 32bit. M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel