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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=no 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 E8C04C433DF for ; Fri, 19 Jun 2020 09:30:54 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 774FE2073E for ; Fri, 19 Jun 2020 09:30:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 774FE2073E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B524F4B18A; Fri, 19 Jun 2020 05:30:53 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 7OhazT7g55nc; Fri, 19 Jun 2020 05:30:52 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 5D2C64B126; Fri, 19 Jun 2020 05:30:52 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 3771A4B126 for ; Fri, 19 Jun 2020 05:30:51 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Ns61qI7v73jt for ; Fri, 19 Jun 2020 05:30:49 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 7DFC94B10F for ; Fri, 19 Jun 2020 05:30:49 -0400 (EDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B5DD12B; Fri, 19 Jun 2020 02:30:48 -0700 (PDT) Received: from entos-d05.shanghai.arm.com (entos-d05.shanghai.arm.com [10.169.40.35]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 883613F71F; Fri, 19 Jun 2020 02:30:42 -0700 (PDT) From: Jianyong Wu To: netdev@vger.kernel.org, yangbo.lu@nxp.com, john.stultz@linaro.org, tglx@linutronix.de, pbonzini@redhat.com, sean.j.christopherson@intel.com, maz@kernel.org, richardcochran@gmail.com, Mark.Rutland@arm.com, will@kernel.org, suzuki.poulose@arm.com, steven.price@arm.com Subject: [RFC PATCH v13 0/9] Enable ptp_kvm for arm64 Date: Fri, 19 Jun 2020 17:30:24 +0800 Message-Id: <20200619093033.58344-1-jianyong.wu@arm.com> X-Mailer: git-send-email 2.17.1 Cc: justin.he@arm.com, Wei.Chen@arm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, nd@arm.com, 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: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Currently, we offen use ntp (sync time with remote network clock) to sync time in VM. But the precision of ntp is subject to network delay so it's difficult to sync time in a high precision. kvm virtual ptp clock (ptp_kvm) offers another way to sync time in VM, as the remote clock locates in the host instead of remote network clock. It targets to sync time between guest and host in virtualization environment and in this way, we can keep the time of all the VMs running in the same host in sync. In general, the delay of communication between host and guest is quiet small, so ptp_kvm can offer time sync precision up to in order of nanosecond. Please keep in mind that ptp_kvm just limits itself to be a channel which transmit the remote clock from host to guest and leaves the time sync jobs to an application, eg. chrony, in usersapce in VM. How ptp_kvm works: After ptp_kvm initialized, there will be a new device node under /dev called ptp%d. A guest userspace service, like chrony, can use this device to get host walltime, sometimes also counter cycle, which depends on the service it calls. Then this guest userspace service can use those data to do the time sync for guest. here is a rough sketch to show how kvm ptp clock works. |----------------------------| |--------------------------| | guest userspace | | host | |ioctl -> /dev/ptp%d | | | | ^ | | | | |----------------------------| | | | | | guest kernel | | | | | V (get host walltime/counter cycle) | | ptp_kvm -> hypercall - - - - - - - - - - ->hypercall service | | <- - - - - - - - - - - - | |----------------------------| |--------------------------| 1. time sync service in guest userspace call ptp device through /dev/ptp%d. 2. ptp_kvm module in guest recive this request then invoke hypercall to route into host kernel to request host walltime/counter cycle. 3. ptp_kvm hypercall service in host response to the request and send data back. 4. ptp (not ptp_kvm) in guest copy the data to userspace. This ptp_kvm implementation focuses itself to step 2 and 3 and step 2 works in guest comparing step 3 works in host kernel. change log: from v12 to v13: (1) rebase code on 5.8-rc1. (2) this patch set base on 2 patches of 1/8 and 2/8 from Will Decon. (3) remove the change to ptp device code of extend getcrosststamp. (4) remove the mechanism of letting user choose the counter type in ptp_kvm for arm64. (5) add virtual counter option in ptp_kvm service to let user choose the specific counter explicitly. from v11 to v12: (1) rebase code on 5.7-rc6 and rebase 2 patches from Will Decon including 1/11 and 2/11. as these patches introduce discover mechanism of vendor smccc service. (2) rebase ptp_kvm hypercall service from standard smccc to vendor smccc and add ptp_kvm to vendor smccc service discover mechanism. (3) add detail of why we need ptp_kvm and how ptp_kvm works in cover letter. from v10 to v11: (1) rebase code on 5.7-rc2. (2) remove support for arm32, as kvm support for arm32 will be removed [1] (3) add error report in ptp_kvm initialization. from v9 to v10: (1) change code base to v5.5. (2) enable ptp_kvm both for arm32 and arm64. (3) let user choose which of virtual counter or physical counter should return when using crosstimestamp mode of ptp_kvm for arm/arm64. (4) extend input argument for getcrosstimestamp API. from v8 to v9: (1) move ptp_kvm.h to driver/ptp/ (2) replace license declaration of ptp_kvm.h the same with other header files in the same directory. from v7 to v8: (1) separate adding clocksource id for arm_arch_counter as a single patch. (2) update commit message for patch 4/8. (3) refine patch 7/8 and patch 8/8 to make them more independent. from v6 to v7: (1) include the omitted clocksource_id.h in last version. (2) reorder the header file in patch. (3) refine some words in commit message to make it more impersonal. from v5 to v6: (1) apply Mark's patch[4] to get SMCCC conduit. (2) add mechanism to recognize current clocksource by add clocksouce_id value into struct clocksource instead of method in patch-v5. (3) rename kvm_arch_ptp_get_clock_fn into kvm_arch_ptp_get_crosststamp. from v3 to v4: (1) fix clocksource of ptp_kvm to arch_sys_counter. (2) move kvm_arch_ptp_get_clock_fn into arm_arch_timer.c (3) subtract cntvoff before return cycles from host. (4) use ktime_get_snapshot instead of getnstimeofday and get_current_counterval to return time and counter value. (5) split ktime and counter into two 32-bit block respectively to avoid Y2038-safe issue. (6) set time compensation to device time as half of the delay of hvc call. (7) add ARM_ARCH_TIMER as dependency of ptp_kvm for arm64. from v2 to v3: (1) fix some issues in commit log. (2) add some receivers in send list. from v1 to v2: (1) move arch-specific code from arch/ to driver/ptp/ (2) offer mechanism to inform userspace if ptp_kvm service is available. (3) separate ptp_kvm code for arm64 into hypervisor part and guest part. (4) add API to expose monotonic clock and counter value. (5) refine code: remove no necessary part and reconsitution. [1] https://patchwork.kernel.org/cover/11373351/ Jianyong Wu (7): arm/arm64: KVM: Advertise KVM UID to guests via SMCCC smccc: export smccc conduit get helper. ptp: Reorganize ptp_kvm modules to make it arch-independent. clocksource: Add clocksource id for arm arch counter arm64/kvm: Add hypercall service for kvm ptp. ptp: arm64: Enable ptp_kvm for arm64 arm64: Add kvm capability check extension for ptp_kvm Thomas Gleixner (1): time: Add mechanism to recognize clocksource in time_get_snapshot Will Deacon (1): arm64: Probe for the presence of KVM hypervisor services during boot arch/arm64/include/asm/hypervisor.h | 11 +++ arch/arm64/kernel/setup.c | 36 +++++++++ arch/arm64/kvm/arm.c | 4 + arch/arm64/kvm/hypercalls.c | 79 +++++++++++++++--- drivers/clocksource/arm_arch_timer.c | 26 ++++++ drivers/firmware/smccc/smccc.c | 1 + drivers/ptp/Kconfig | 2 +- drivers/ptp/Makefile | 1 + drivers/ptp/ptp_kvm.h | 11 +++ drivers/ptp/ptp_kvm_arm64.c | 53 ++++++++++++ drivers/ptp/{ptp_kvm.c => ptp_kvm_common.c} | 80 +++++------------- drivers/ptp/ptp_kvm_x86.c | 89 +++++++++++++++++++++ include/linux/arm-smccc.h | 56 +++++++++++++ include/linux/clocksource.h | 6 ++ include/linux/clocksource_ids.h | 12 +++ include/linux/timekeeping.h | 12 +-- include/uapi/linux/kvm.h | 1 + kernel/time/clocksource.c | 3 + kernel/time/timekeeping.c | 1 + virt/kvm/Kconfig | 4 + 20 files changed, 413 insertions(+), 75 deletions(-) create mode 100644 drivers/ptp/ptp_kvm.h create mode 100644 drivers/ptp/ptp_kvm_arm64.c rename drivers/ptp/{ptp_kvm.c => ptp_kvm_common.c} (63%) create mode 100644 drivers/ptp/ptp_kvm_x86.c create mode 100644 include/linux/clocksource_ids.h -- 2.17.1 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm