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=-14.0 required=3.0 tests=BAYES_00,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 33885C433E0 for ; Tue, 2 Feb 2021 13:40:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EABB664F7F for ; Tue, 2 Feb 2021 13:40:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232720AbhBBNkn (ORCPT ); Tue, 2 Feb 2021 08:40:43 -0500 Received: from mail.kernel.org ([198.145.29.99]:34408 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232566AbhBBNiM (ORCPT ); Tue, 2 Feb 2021 08:38:12 -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 15CB864DDA; Tue, 2 Feb 2021 13:37:31 +0000 (UTC) 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 1l6vs0-00BVCV-8p; Tue, 02 Feb 2021 13:37:29 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 02 Feb 2021 13:37:28 +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 v16 7/9] ptp: arm/arm64: Enable ptp_kvm for arm/arm64 In-Reply-To: <20201209060932.212364-8-jianyong.wu@arm.com> References: <20201209060932.212364-1-jianyong.wu@arm.com> <20201209060932.212364-8-jianyong.wu@arm.com> User-Agent: Roundcube Webmail/1.4.10 Message-ID: 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: netdev@vger.kernel.org On 2020-12-09 06:09, 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 environment, we > ask > 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 > 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 | 29 ++++++++++++++++++ > drivers/ptp/Kconfig | 2 +- > drivers/ptp/Makefile | 1 + > drivers/ptp/ptp_kvm_arm.c | 45 ++++++++++++++++++++++++++++ > 4 files changed, 76 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..16cd0a663587 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -25,6 +25,8 @@ > #include > #include > #include > +#include > +#include > > #include > #include > @@ -1650,3 +1652,30 @@ 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; > + *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..ecb5ef273be5 > --- /dev/null > +++ b/drivers/ptp/ptp_kvm_arm.c > @@ -0,0 +1,45 @@ > +// 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 > +#include > + > +int kvm_arch_ptp_init(void) > +{ > + int ret; > + > + ret = kvm_arm_hyp_service_available(ARM_SMCCC_KVM_FUNC_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_VIRT_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); This whole function can be trivially replaced with a call to kvm_arch_ptp_get_crosststamp with minimal changes to that function: diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index e3a5ebbfb3d0..e7b07166e771 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -1663,16 +1663,16 @@ 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 clocksource **cs) { struct arm_smccc_res hvc_res; - ktime_t ktime; u32 ptp_counter; + ktime_t ktime; if (arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) - ptp_counter = ARM_PTP_VIRT_COUNTER; + ptp_counter = KVM_PTP_VIRT_COUNTER; else - ptp_counter = ARM_PTP_PHY_COUNTER; + ptp_counter = KVM_PTP_PHYS_COUNTER; arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, ptp_counter, &hvc_res); @@ -1682,8 +1682,10 @@ int kvm_arch_ptp_get_crosststamp(u64 *cycle, struct timespec64 *ts, ktime = (u64)hvc_res.a0 << 32 | hvc_res.a1; *ts = ktime_to_timespec64(ktime); - *cycle = (u64)hvc_res.a2 << 32 | hvc_res.a3; - *cs = &clocksource_counter; + if (cycle) + *cycle = (u64)hvc_res.a2 << 32 | hvc_res.a3; + if (cs) + *cs = &clocksource_counter; return 0; } diff --git a/drivers/ptp/ptp_kvm_arm.c b/drivers/ptp/ptp_kvm_arm.c index ecb5ef273be5..b7d28c8dfb84 100644 --- a/drivers/ptp/ptp_kvm_arm.c +++ b/drivers/ptp/ptp_kvm_arm.c @@ -5,15 +5,9 @@ * All Rights Reserved */ -#include -#include -#include -#include -#include #include -#include #include -#include + #include #include @@ -30,16 +24,5 @@ int kvm_arch_ptp_init(void) 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_VIRT_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); - - return 0; + return kvm_arch_ptp_get_crosststamp(NULL, ts, NULL); } Thanks, M. -- Jazz is not dead. It just smells funny...