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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] Xen physical cpus online/offline sys interface
On Mon, Jun 11, 2012 at 05:56:29AM +0000, Liu, Jinsong wrote:
> Konrad,
>
> Our old patch of cpu online/offline is based on old kernel tree.
> I rebase it to your latest xen.git
> git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git branch
> devel/mce.v3
applied.
>
> Thanks,
> Jinsong
>
> =====================
> >From 29152bb054d87334ef970ad037888b7bb032f8ef Mon Sep 17 00:00:00 2001
> From: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
> Date: Mon, 11 Jun 2012 20:38:08 +0800
> Subject: [PATCH] Xen physical cpus online/offline sys interface
>
> This patch provide Xen physical cpus online/offline sys interface.
> User can use it for their own purpose, like power saving:
> by offlining some cpus when light workload it save power greatly.
>
> Its basic workflow is, user online/offline cpu via sys interface,
> then hypercall xen to implement, after done xen inject virq back to dom0,
> and then dom0 sync cpu status.
>
> Signed-off-by: Jiang, Yunhong <yunhong.jiang@xxxxxxxxx>
> Signed-off-by: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
> ---
> .../ABI/testing/sysfs-devices-system-xen_cpu | 20 +
> drivers/xen/Makefile | 1 +
> drivers/xen/pcpu.c | 371
> ++++++++++++++++++++
> include/xen/interface/platform.h | 8 +
> include/xen/interface/xen.h | 1 +
> 5 files changed, 401 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-devices-system-xen_cpu
> create mode 100644 drivers/xen/pcpu.c
>
> diff --git a/Documentation/ABI/testing/sysfs-devices-system-xen_cpu
> b/Documentation/ABI/testing/sysfs-devices-system-xen_cpu
> new file mode 100644
> index 0000000..9ca02fb
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-devices-system-xen_cpu
> @@ -0,0 +1,20 @@
> +What: /sys/devices/system/xen_cpu/
> +Date: May 2012
> +Contact: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
> +Description:
> + A collection of global/individual Xen physical cpu attributes
> +
> + Individual physical cpu attributes are contained in
> + subdirectories named by the Xen's logical cpu number, e.g.:
> + /sys/devices/system/xen_cpu/xen_cpu#/
> +
> +
> +What: /sys/devices/system/xen_cpu/xen_cpu#/online
> +Date: May 2012
> +Contact: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
> +Description:
> + Interface to online/offline Xen physical cpus
> +
> + When running under Xen platform, it provide user interface
> + to online/offline physical cpus, except cpu0 due to several
> + logic restrictions and assumptions.
> diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
> index a787029..d80bea5 100644
> --- a/drivers/xen/Makefile
> +++ b/drivers/xen/Makefile
> @@ -17,6 +17,7 @@ obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o
> obj-$(CONFIG_XEN_PVHVM) += platform-pci.o
> obj-$(CONFIG_XEN_TMEM) += tmem.o
> obj-$(CONFIG_SWIOTLB_XEN) += swiotlb-xen.o
> +obj-$(CONFIG_XEN_DOM0) += pcpu.o
> obj-$(CONFIG_XEN_DOM0) += pci.o acpi.o
> obj-$(CONFIG_XEN_MCE_LOG) += mcelog.o
> obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback/
> diff --git a/drivers/xen/pcpu.c b/drivers/xen/pcpu.c
> new file mode 100644
> index 0000000..067fcfa
> --- /dev/null
> +++ b/drivers/xen/pcpu.c
> @@ -0,0 +1,371 @@
> +/******************************************************************************
> + * pcpu.c
> + * Management physical cpu in dom0, get pcpu info and provide sys interface
> + *
> + * Copyright (c) 2012 Intel Corporation
> + * Author: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
> + * Author: Jiang, Yunhong <yunhong.jiang@xxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation; or, when distributed
> + * separately from the Linux kernel or incorporated into other
> + * software packages, subject to the following license:
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> copy
> + * of this source file (the "Software"), to deal in the Software without
> + * restriction, including without limitation the rights to use, copy, modify,
> + * merge, publish, distribute, sublicense, and/or sell copies of the
> Software,
> + * and to permit persons to whom the Software is furnished to do so, subject
> to
> + * the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> THE
> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#include <linux/interrupt.h>
> +#include <linux/spinlock.h>
> +#include <linux/cpu.h>
> +#include <linux/stat.h>
> +#include <linux/capability.h>
> +
> +#include <xen/xen.h>
> +#include <xen/xenbus.h>
> +#include <xen/events.h>
> +#include <xen/interface/platform.h>
> +#include <asm/xen/hypervisor.h>
> +#include <asm/xen/hypercall.h>
> +
> +#define XEN_PCPU "xen_cpu: "
> +
> +/*
> + * @cpu_id: Xen physical cpu logic number
> + * @flags: Xen physical cpu status flag
> + * - XEN_PCPU_FLAGS_ONLINE: cpu is online
> + * - XEN_PCPU_FLAGS_INVALID: cpu is not present
> + */
> +struct pcpu {
> + struct list_head list;
> + struct device dev;
> + uint32_t cpu_id;
> + uint32_t flags;
> +};
> +
> +static struct bus_type xen_pcpu_subsys = {
> + .name = "xen_cpu",
> + .dev_name = "xen_cpu",
> +};
> +
> +static DEFINE_MUTEX(xen_pcpu_lock);
> +
> +static LIST_HEAD(xen_pcpus);
> +
> +static int xen_pcpu_down(uint32_t cpu_id)
> +{
> + struct xen_platform_op op = {
> + .cmd = XENPF_cpu_offline,
> + .interface_version = XENPF_INTERFACE_VERSION,
> + .u.cpu_ol.cpuid = cpu_id,
> + };
> +
> + return HYPERVISOR_dom0_op(&op);
> +}
> +
> +static int xen_pcpu_up(uint32_t cpu_id)
> +{
> + struct xen_platform_op op = {
> + .cmd = XENPF_cpu_online,
> + .interface_version = XENPF_INTERFACE_VERSION,
> + .u.cpu_ol.cpuid = cpu_id,
> + };
> +
> + return HYPERVISOR_dom0_op(&op);
> +}
> +
> +static ssize_t show_online(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct pcpu *cpu = container_of(dev, struct pcpu, dev);
> +
> + return sprintf(buf, "%u\n", !!(cpu->flags & XEN_PCPU_FLAGS_ONLINE));
> +}
> +
> +static ssize_t __ref store_online(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct pcpu *pcpu = container_of(dev, struct pcpu, dev);
> + unsigned long long val;
> + ssize_t ret;
> +
> + if (!capable(CAP_SYS_ADMIN))
> + return -EPERM;
> +
> + if (kstrtoull(buf, 0, &val) < 0)
> + return -EINVAL;
> +
> + switch (val) {
> + case 0:
> + ret = xen_pcpu_down(pcpu->cpu_id);
> + break;
> + case 1:
> + ret = xen_pcpu_up(pcpu->cpu_id);
> + break;
> + default:
> + ret = -EINVAL;
> + }
> +
> + if (ret >= 0)
> + ret = count;
> + return ret;
> +}
> +static DEVICE_ATTR(online, S_IRUGO | S_IWUSR, show_online, store_online);
> +
> +static bool xen_pcpu_online(uint32_t flags)
> +{
> + return !!(flags & XEN_PCPU_FLAGS_ONLINE);
> +}
> +
> +static void pcpu_online_status(struct xenpf_pcpuinfo *info,
> + struct pcpu *pcpu)
> +{
> + if (xen_pcpu_online(info->flags) &&
> + !xen_pcpu_online(pcpu->flags)) {
> + /* the pcpu is onlined */
> + pcpu->flags |= XEN_PCPU_FLAGS_ONLINE;
> + kobject_uevent(&pcpu->dev.kobj, KOBJ_ONLINE);
> + } else if (!xen_pcpu_online(info->flags) &&
> + xen_pcpu_online(pcpu->flags)) {
> + /* The pcpu is offlined */
> + pcpu->flags &= ~XEN_PCPU_FLAGS_ONLINE;
> + kobject_uevent(&pcpu->dev.kobj, KOBJ_OFFLINE);
> + }
> +}
> +
> +static struct pcpu *get_pcpu(uint32_t cpu_id)
> +{
> + struct pcpu *pcpu;
> +
> + list_for_each_entry(pcpu, &xen_pcpus, list) {
> + if (pcpu->cpu_id == cpu_id)
> + return pcpu;
> + }
> +
> + return NULL;
> +}
> +
> +static void pcpu_release(struct device *dev)
> +{
> + struct pcpu *pcpu = container_of(dev, struct pcpu, dev);
> +
> + list_del(&pcpu->list);
> + kfree(pcpu);
> +}
> +
> +static void unregister_and_remove_pcpu(struct pcpu *pcpu)
> +{
> + struct device *dev;
> +
> + if (!pcpu)
> + return;
> +
> + dev = &pcpu->dev;
> + if (dev->id)
> + device_remove_file(dev, &dev_attr_online);
> +
> + /* pcpu remove would be implicitly done */
> + device_unregister(dev);
> +}
> +
> +static int register_pcpu(struct pcpu *pcpu)
> +{
> + struct device *dev;
> + int err = -EINVAL;
> +
> + if (!pcpu)
> + return err;
> +
> + dev = &pcpu->dev;
> + dev->bus = &xen_pcpu_subsys;
> + dev->id = pcpu->cpu_id;
> + dev->release = pcpu_release;
> +
> + err = device_register(dev);
> + if (err) {
> + pcpu_release(dev);
> + return err;
> + }
> +
> + /*
> + * Xen never offline cpu0 due to several restrictions
> + * and assumptions. This basically doesn't add a sys control
> + * to user, one cannot attempt to offline BSP.
> + */
> + if (dev->id) {
> + err = device_create_file(dev, &dev_attr_online);
> + if (err) {
> + device_unregister(dev);
> + return err;
> + }
> + }
> +
> + return 0;
> +}
> +
> +static struct pcpu *create_and_register_pcpu(struct xenpf_pcpuinfo *info)
> +{
> + struct pcpu *pcpu;
> + int err;
> +
> + if (info->flags & XEN_PCPU_FLAGS_INVALID)
> + return ERR_PTR(-ENODEV);
> +
> + pcpu = kzalloc(sizeof(struct pcpu), GFP_KERNEL);
> + if (!pcpu)
> + return ERR_PTR(-ENOMEM);
> +
> + INIT_LIST_HEAD(&pcpu->list);
> + pcpu->cpu_id = info->xen_cpuid;
> + pcpu->flags = info->flags;
> +
> + /* Need hold on xen_pcpu_lock before pcpu list manipulations */
> + list_add_tail(&pcpu->list, &xen_pcpus);
> +
> + err = register_pcpu(pcpu);
> + if (err) {
> + pr_warning(XEN_PCPU "Failed to register pcpu%u\n",
> + info->xen_cpuid);
> + return ERR_PTR(-ENOENT);
> + }
> +
> + return pcpu;
> +}
> +
> +/*
> + * Caller should hold the xen_pcpu_lock
> + */
> +static int sync_pcpu(uint32_t cpu, uint32_t *max_cpu)
> +{
> + int ret;
> + struct pcpu *pcpu = NULL;
> + struct xenpf_pcpuinfo *info;
> + struct xen_platform_op op = {
> + .cmd = XENPF_get_cpuinfo,
> + .interface_version = XENPF_INTERFACE_VERSION,
> + .u.pcpu_info.xen_cpuid = cpu,
> + };
> +
> + ret = HYPERVISOR_dom0_op(&op);
> + if (ret)
> + return ret;
> +
> + info = &op.u.pcpu_info;
> + if (max_cpu)
> + *max_cpu = info->max_present;
> +
> + pcpu = get_pcpu(cpu);
> +
> + /*
> + * Only those at cpu present map has its sys interface.
> + */
> + if (info->flags & XEN_PCPU_FLAGS_INVALID) {
> + if (pcpu)
> + unregister_and_remove_pcpu(pcpu);
> + return 0;
> + }
> +
> + if (!pcpu) {
> + pcpu = create_and_register_pcpu(info);
> + if (IS_ERR_OR_NULL(pcpu))
> + return -ENODEV;
> + } else
> + pcpu_online_status(info, pcpu);
> +
> + return 0;
> +}
> +
> +/*
> + * Sync dom0's pcpu information with xen hypervisor's
> + */
> +static int xen_sync_pcpus(void)
> +{
> + /*
> + * Boot cpu always have cpu_id 0 in xen
> + */
> + uint32_t cpu = 0, max_cpu = 0;
> + int err = 0;
> + struct pcpu *pcpu, *tmp;
> +
> + mutex_lock(&xen_pcpu_lock);
> +
> + while (!err && (cpu <= max_cpu)) {
> + err = sync_pcpu(cpu, &max_cpu);
> + cpu++;
> + }
> +
> + if (err)
> + list_for_each_entry_safe(pcpu, tmp, &xen_pcpus, list)
> + unregister_and_remove_pcpu(pcpu);
> +
> + mutex_unlock(&xen_pcpu_lock);
> +
> + return err;
> +}
> +
> +static void xen_pcpu_work_fn(struct work_struct *work)
> +{
> + xen_sync_pcpus();
> +}
> +static DECLARE_WORK(xen_pcpu_work, xen_pcpu_work_fn);
> +
> +static irqreturn_t xen_pcpu_interrupt(int irq, void *dev_id)
> +{
> + schedule_work(&xen_pcpu_work);
> + return IRQ_HANDLED;
> +}
> +
> +static int __init xen_pcpu_init(void)
> +{
> + int irq, ret;
> +
> + if (!xen_initial_domain())
> + return -ENODEV;
> +
> + irq = bind_virq_to_irqhandler(VIRQ_PCPU_STATE, 0,
> + xen_pcpu_interrupt, 0,
> + "xen-pcpu", NULL);
> + if (irq < 0) {
> + pr_warning(XEN_PCPU "Failed to bind pcpu virq\n");
> + return irq;
> + }
> +
> + ret = subsys_system_register(&xen_pcpu_subsys, NULL);
> + if (ret) {
> + pr_warning(XEN_PCPU "Failed to register pcpu subsys\n");
> + goto err1;
> + }
> +
> + ret = xen_sync_pcpus();
> + if (ret) {
> + pr_warning(XEN_PCPU "Failed to sync pcpu info\n");
> + goto err2;
> + }
> +
> + return 0;
> +
> +err2:
> + bus_unregister(&xen_pcpu_subsys);
> +err1:
> + unbind_from_irqhandler(irq, NULL);
> + return ret;
> +}
> +arch_initcall(xen_pcpu_init);
> diff --git a/include/xen/interface/platform.h
> b/include/xen/interface/platform.h
> index 486653f..61fa661 100644
> --- a/include/xen/interface/platform.h
> +++ b/include/xen/interface/platform.h
> @@ -314,6 +314,13 @@ struct xenpf_pcpuinfo {
> };
> DEFINE_GUEST_HANDLE_STRUCT(xenpf_pcpuinfo);
>
> +#define XENPF_cpu_online 56
> +#define XENPF_cpu_offline 57
> +struct xenpf_cpu_ol {
> + uint32_t cpuid;
> +};
> +DEFINE_GUEST_HANDLE_STRUCT(xenpf_cpu_ol);
> +
> struct xen_platform_op {
> uint32_t cmd;
> uint32_t interface_version; /* XENPF_INTERFACE_VERSION */
> @@ -330,6 +337,7 @@ struct xen_platform_op {
> struct xenpf_getidletime getidletime;
> struct xenpf_set_processor_pminfo set_pminfo;
> struct xenpf_pcpuinfo pcpu_info;
> + struct xenpf_cpu_ol cpu_ol;
> uint8_t pad[128];
> } u;
> };
> diff --git a/include/xen/interface/xen.h b/include/xen/interface/xen.h
> index a890804..0801468 100644
> --- a/include/xen/interface/xen.h
> +++ b/include/xen/interface/xen.h
> @@ -80,6 +80,7 @@
> #define VIRQ_CONSOLE 2 /* (DOM0) Bytes received on emergency console. */
> #define VIRQ_DOM_EXC 3 /* (DOM0) Exceptional event for some domain. */
> #define VIRQ_DEBUGGER 6 /* (DOM0) A domain has paused for debugging. */
> +#define VIRQ_PCPU_STATE 9 /* (DOM0) PCPU state changed */
>
> /* Architecture-specific VIRQ definitions. */
> #define VIRQ_ARCH_0 16
> --
> 1.7.1
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel
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