From patchwork Mon Mar 23 13:50:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qais Yousef X-Patchwork-Id: 11453045 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A109917D4 for ; Mon, 23 Mar 2020 13:52:37 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 8590E2072D for ; Mon, 23 Mar 2020 13:52:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8590E2072D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1jGNU8-0002kx-OL; Mon, 23 Mar 2020 13:51:20 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1jGNU7-0002ks-0L for xen-devel@lists.xenproject.org; Mon, 23 Mar 2020 13:51:19 +0000 X-Inumbo-ID: 5e7157c2-6d0d-11ea-92cf-bc764e2007e4 Received: from foss.arm.com (unknown [217.140.110.172]) by us1-rack-iad1.inumbo.com (Halon) with ESMTP id 5e7157c2-6d0d-11ea-92cf-bc764e2007e4; Mon, 23 Mar 2020 13:51:17 +0000 (UTC) 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 2962E1FB; Mon, 23 Mar 2020 06:51:17 -0700 (PDT) Received: from e107158-lin.cambridge.arm.com (e107158-lin.cambridge.arm.com [10.1.195.21]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 82C293F52E; Mon, 23 Mar 2020 06:51:14 -0700 (PDT) From: Qais Yousef To: Thomas Gleixner Date: Mon, 23 Mar 2020 13:50:53 +0000 Message-Id: <20200323135110.30522-1-qais.yousef@arm.com> X-Mailer: git-send-email 2.17.1 Subject: [Xen-devel] [PATCH v4 00/17] Convert cpu_up/down to device_online/offline X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Fenghua Yu , Tony Luck , linux-ia64@vger.kernel.org, linux-parisc@vger.kernel.org, "Paul E. McKenney" , "David S. Miller" , Catalin Marinas , Helge Deller , x86@kernel.org, Russell King , linux-kernel@vger.kernel.org, Lorenzo Pieralisi , Greg Kroah-Hartman , Michael Ellerman , sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, Mark Rutland , linuxppc-dev@lists.ozlabs.org, Qais Yousef , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" ============= Changes in v4 ============= * Split arm and arm64 patches so that the change to use reboot_cpu goes into its own separate patch (Russell) * Collected new Acked-by * Rebased on top of v5.6-rc6 * Trimmed the CC list on the cover letter as lists were rejecting it git clone git://linux-arm.org/linux-qy.git -b cpu-hp-cleanup-v4 Older post can be found here ---------------------------- https://lore.kernel.org/lkml/20200223192942.18420-2-qais.yousef@arm.com/ ============= Test Coverage ============= All tests ran with LOCKDEP enabled. Platform: Juno-r2: arm64 ------------------------ * Overnight rcutorture * Overnight locktorture * kexec -f Image --command="$(cat /proc/cmdline) reboot=s[0-5]" * Hibernate to disk (using suspend option) * Userspace hotplug via sysfs * PSCI firemware checker Notes: * Couldn't convince Juno to hibernate using [reboot] or [shutdown] options. Platform: qemu (8 vCPUs) and VM (2 vCPUs): x86_64 ------------------------------------------------- * Overnight rcutorture * Overnight locktorture * Userspace hotplug via sysfs * echo mmiotrace > /sys/kernel/debug/tracing/current_tracer && echo nop > /sys/kernel/debug/tracing/current_tracer * Ran with CONFIG_DEBUG_HOTPLUG_CPU0 and CONFIG_BOOTPARAM_HOTPLUG_CPU0 Notes: * qemu failed to bring cpu0 after offlining. Same behavior observed on vanilla v5.6-rc6. Worked fine on the VM. * mmiotrace successfully brought down all cpus when enabled, then back online again when disabled. Including when cpu0 was offline. * My xen shenanigans are too 'humble' too create environment to test the change in xen yet.. ===================== Original Cover Letter ===================== Using cpu_up/down directly to bring cpus online/offline loses synchronization with sysfs and could suffer from a race similar to what is described in commit a6717c01ddc2 ("powerpc/rtas: use device model APIs and serialization during LPM"). cpu_up/down seem to be more of a internal implementation detail for the cpu subsystem to use to boot up cpus, perform suspend/resume and low level hotplug operations. Users outside of the cpu subsystem would be better using the device core API to bring a cpu online/offline which is the interface used to hotplug memory and other system devices. Several users have already migrated to use the device core API, this series converts the remaining users and hides cpu_up/down from internal users at the end. I noticed this problem while working on a hack to disable offlining a particular CPU but noticed that setting the offline_disabled attribute in the device struct isn't enough because users can easily bypass the device core. While my hack isn't a valid use case but it did highlight the inconsistency in the way cpus are being onlined/offlined and this attempt hopefully improves on this. The first patch introduces new API to {add,remove}_cpu() using device_{online, offline}() with correct locks held and export it. The following 10 patches fix arch users. The remaining 6 patches fix generic code users. Particularly creating a new special exported API for the device core to use instead of cpu_up/down. The last patch removes cpu_up/down from cpu.h and unexport the functions. In some cases where the use of cpu_up/down seemed legitimate, I encapsulated the logic in a higher level - special purposed function; and converted the code to use that instead. CC: Thomas Gleixner CC: Tony Luck CC: Fenghua Yu CC: Russell King CC: Catalin Marinas CC: Michael Ellerman CC: "David S. Miller" CC: Helge Deller CC: Juergen Gross CC: Mark Rutland CC: Lorenzo Pieralisi CC: "Paul E. McKenney" CC: Greg Kroah-Hartman CC: xen-devel@lists.xenproject.org CC: linux-parisc@vger.kernel.org CC: sparclinux@vger.kernel.org CC: linuxppc-dev@lists.ozlabs.org CC: x86@kernel.org CC: linux-arm-kernel@lists.infradead.org CC: linux-ia64@vger.kernel.org CC: linux-kernel@vger.kernel.org Qais Yousef (17): cpu: Add new {add,remove}_cpu() functions smp: Create a new function to shutdown nonboot cpus ia64: Replace cpu_down with smp_shutdown_nonboot_cpus() arm: Don't use disable_nonboot_cpus() arm: Use reboot_cpu instead of hardcoding it to 0 arm64: Don't use disable_nonboot_cpus() arm64: Use reboot_cpu instead of hardconding it to 0 arm64: hibernate.c: Create a new function to handle cpu_up(sleep_cpu) x86: Replace cpu_up/down with add/remove_cpu powerpc: Replace cpu_up/down with add/remove_cpu sparc: Replace cpu_up/down with add/remove_cpu parisc: Replace cpu_up/down with add/remove_cpu driver: xen: Replace cpu_up/down with device_online/offline firmware: psci: Replace cpu_up/down with add/remove_cpu torture: Replace cpu_up/down with add/remove_cpu smp: Create a new function to bringup nonboot cpus online cpu: Hide cpu_up/down arch/arm/kernel/reboot.c | 4 +- arch/arm64/kernel/hibernate.c | 13 +-- arch/arm64/kernel/process.c | 4 +- arch/ia64/kernel/process.c | 8 +- arch/parisc/kernel/processor.c | 2 +- arch/powerpc/kexec/core_64.c | 2 +- arch/sparc/kernel/ds.c | 4 +- arch/x86/kernel/topology.c | 22 ++--- arch/x86/mm/mmio-mod.c | 4 +- arch/x86/xen/smp.c | 2 +- drivers/base/cpu.c | 4 +- drivers/firmware/psci/psci_checker.c | 4 +- drivers/xen/cpu_hotplug.c | 2 +- include/linux/cpu.h | 10 +- kernel/cpu.c | 134 ++++++++++++++++++++++++++- kernel/smp.c | 9 +- kernel/torture.c | 9 +- 17 files changed, 172 insertions(+), 65 deletions(-)