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https://github.com/torvalds/linux
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xen/pcpu: 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@intel.com> Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
parent
05e36006ad
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20
Documentation/ABI/testing/sysfs-devices-system-xen_cpu
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20
Documentation/ABI/testing/sysfs-devices-system-xen_cpu
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@ -0,0 +1,20 @@
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What: /sys/devices/system/xen_cpu/
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Date: May 2012
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Contact: Liu, Jinsong <jinsong.liu@intel.com>
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Description:
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A collection of global/individual Xen physical cpu attributes
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Individual physical cpu attributes are contained in
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subdirectories named by the Xen's logical cpu number, e.g.:
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/sys/devices/system/xen_cpu/xen_cpu#/
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What: /sys/devices/system/xen_cpu/xen_cpu#/online
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Date: May 2012
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Contact: Liu, Jinsong <jinsong.liu@intel.com>
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Description:
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Interface to online/offline Xen physical cpus
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When running under Xen platform, it provide user interface
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to online/offline physical cpus, except cpu0 due to several
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logic restrictions and assumptions.
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@ -17,6 +17,7 @@ obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o
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obj-$(CONFIG_XEN_PVHVM) += platform-pci.o
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obj-$(CONFIG_XEN_TMEM) += tmem.o
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obj-$(CONFIG_SWIOTLB_XEN) += swiotlb-xen.o
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obj-$(CONFIG_XEN_DOM0) += pcpu.o
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obj-$(CONFIG_XEN_DOM0) += pci.o acpi.o
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obj-$(CONFIG_XEN_MCE_LOG) += mcelog.o
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obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback/
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371
drivers/xen/pcpu.c
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371
drivers/xen/pcpu.c
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@ -0,0 +1,371 @@
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/******************************************************************************
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* pcpu.c
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* Management physical cpu in dom0, get pcpu info and provide sys interface
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*
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* Copyright (c) 2012 Intel Corporation
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* Author: Liu, Jinsong <jinsong.liu@intel.com>
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* Author: Jiang, Yunhong <yunhong.jiang@intel.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation; or, when distributed
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* separately from the Linux kernel or incorporated into other
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* software packages, subject to the following license:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this source file (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy, modify,
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* merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include <linux/interrupt.h>
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#include <linux/spinlock.h>
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#include <linux/cpu.h>
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#include <linux/stat.h>
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#include <linux/capability.h>
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#include <xen/xen.h>
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#include <xen/xenbus.h>
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#include <xen/events.h>
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#include <xen/interface/platform.h>
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#include <asm/xen/hypervisor.h>
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#include <asm/xen/hypercall.h>
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#define XEN_PCPU "xen_cpu: "
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/*
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* @cpu_id: Xen physical cpu logic number
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* @flags: Xen physical cpu status flag
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* - XEN_PCPU_FLAGS_ONLINE: cpu is online
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* - XEN_PCPU_FLAGS_INVALID: cpu is not present
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*/
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struct pcpu {
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struct list_head list;
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struct device dev;
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uint32_t cpu_id;
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uint32_t flags;
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};
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static struct bus_type xen_pcpu_subsys = {
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.name = "xen_cpu",
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.dev_name = "xen_cpu",
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};
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static DEFINE_MUTEX(xen_pcpu_lock);
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static LIST_HEAD(xen_pcpus);
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static int xen_pcpu_down(uint32_t cpu_id)
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{
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struct xen_platform_op op = {
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.cmd = XENPF_cpu_offline,
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.interface_version = XENPF_INTERFACE_VERSION,
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.u.cpu_ol.cpuid = cpu_id,
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};
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return HYPERVISOR_dom0_op(&op);
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}
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static int xen_pcpu_up(uint32_t cpu_id)
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{
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struct xen_platform_op op = {
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.cmd = XENPF_cpu_online,
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.interface_version = XENPF_INTERFACE_VERSION,
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.u.cpu_ol.cpuid = cpu_id,
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};
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return HYPERVISOR_dom0_op(&op);
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}
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static ssize_t show_online(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct pcpu *cpu = container_of(dev, struct pcpu, dev);
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return sprintf(buf, "%u\n", !!(cpu->flags & XEN_PCPU_FLAGS_ONLINE));
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}
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static ssize_t __ref store_online(struct device *dev,
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struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct pcpu *pcpu = container_of(dev, struct pcpu, dev);
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unsigned long long val;
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ssize_t ret;
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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if (kstrtoull(buf, 0, &val) < 0)
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return -EINVAL;
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switch (val) {
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case 0:
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ret = xen_pcpu_down(pcpu->cpu_id);
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break;
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case 1:
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ret = xen_pcpu_up(pcpu->cpu_id);
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break;
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default:
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ret = -EINVAL;
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}
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if (ret >= 0)
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ret = count;
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return ret;
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}
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static DEVICE_ATTR(online, S_IRUGO | S_IWUSR, show_online, store_online);
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static bool xen_pcpu_online(uint32_t flags)
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{
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return !!(flags & XEN_PCPU_FLAGS_ONLINE);
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}
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static void pcpu_online_status(struct xenpf_pcpuinfo *info,
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struct pcpu *pcpu)
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{
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if (xen_pcpu_online(info->flags) &&
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!xen_pcpu_online(pcpu->flags)) {
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/* the pcpu is onlined */
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pcpu->flags |= XEN_PCPU_FLAGS_ONLINE;
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kobject_uevent(&pcpu->dev.kobj, KOBJ_ONLINE);
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} else if (!xen_pcpu_online(info->flags) &&
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xen_pcpu_online(pcpu->flags)) {
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/* The pcpu is offlined */
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pcpu->flags &= ~XEN_PCPU_FLAGS_ONLINE;
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kobject_uevent(&pcpu->dev.kobj, KOBJ_OFFLINE);
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}
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}
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static struct pcpu *get_pcpu(uint32_t cpu_id)
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{
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struct pcpu *pcpu;
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list_for_each_entry(pcpu, &xen_pcpus, list) {
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if (pcpu->cpu_id == cpu_id)
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return pcpu;
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}
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return NULL;
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}
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static void pcpu_release(struct device *dev)
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{
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struct pcpu *pcpu = container_of(dev, struct pcpu, dev);
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list_del(&pcpu->list);
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kfree(pcpu);
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}
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static void unregister_and_remove_pcpu(struct pcpu *pcpu)
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{
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struct device *dev;
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if (!pcpu)
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return;
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dev = &pcpu->dev;
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if (dev->id)
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device_remove_file(dev, &dev_attr_online);
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/* pcpu remove would be implicitly done */
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device_unregister(dev);
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}
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static int register_pcpu(struct pcpu *pcpu)
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{
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struct device *dev;
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int err = -EINVAL;
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if (!pcpu)
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return err;
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dev = &pcpu->dev;
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dev->bus = &xen_pcpu_subsys;
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dev->id = pcpu->cpu_id;
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dev->release = pcpu_release;
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err = device_register(dev);
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if (err) {
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pcpu_release(dev);
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return err;
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}
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/*
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* Xen never offline cpu0 due to several restrictions
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* and assumptions. This basically doesn't add a sys control
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* to user, one cannot attempt to offline BSP.
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*/
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if (dev->id) {
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err = device_create_file(dev, &dev_attr_online);
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if (err) {
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device_unregister(dev);
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return err;
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}
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}
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return 0;
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}
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static struct pcpu *create_and_register_pcpu(struct xenpf_pcpuinfo *info)
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{
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struct pcpu *pcpu;
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int err;
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if (info->flags & XEN_PCPU_FLAGS_INVALID)
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return ERR_PTR(-ENODEV);
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pcpu = kzalloc(sizeof(struct pcpu), GFP_KERNEL);
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if (!pcpu)
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return ERR_PTR(-ENOMEM);
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INIT_LIST_HEAD(&pcpu->list);
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pcpu->cpu_id = info->xen_cpuid;
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pcpu->flags = info->flags;
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/* Need hold on xen_pcpu_lock before pcpu list manipulations */
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list_add_tail(&pcpu->list, &xen_pcpus);
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err = register_pcpu(pcpu);
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if (err) {
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pr_warning(XEN_PCPU "Failed to register pcpu%u\n",
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info->xen_cpuid);
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return ERR_PTR(-ENOENT);
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}
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return pcpu;
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}
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/*
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* Caller should hold the xen_pcpu_lock
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*/
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static int sync_pcpu(uint32_t cpu, uint32_t *max_cpu)
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{
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int ret;
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struct pcpu *pcpu = NULL;
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struct xenpf_pcpuinfo *info;
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struct xen_platform_op op = {
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.cmd = XENPF_get_cpuinfo,
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.interface_version = XENPF_INTERFACE_VERSION,
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.u.pcpu_info.xen_cpuid = cpu,
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};
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ret = HYPERVISOR_dom0_op(&op);
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if (ret)
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return ret;
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info = &op.u.pcpu_info;
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if (max_cpu)
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*max_cpu = info->max_present;
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pcpu = get_pcpu(cpu);
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/*
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* Only those at cpu present map has its sys interface.
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*/
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if (info->flags & XEN_PCPU_FLAGS_INVALID) {
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if (pcpu)
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unregister_and_remove_pcpu(pcpu);
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return 0;
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}
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if (!pcpu) {
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pcpu = create_and_register_pcpu(info);
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if (IS_ERR_OR_NULL(pcpu))
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return -ENODEV;
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} else
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pcpu_online_status(info, pcpu);
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return 0;
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}
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/*
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* Sync dom0's pcpu information with xen hypervisor's
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*/
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static int xen_sync_pcpus(void)
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{
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/*
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* Boot cpu always have cpu_id 0 in xen
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*/
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uint32_t cpu = 0, max_cpu = 0;
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int err = 0;
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struct pcpu *pcpu, *tmp;
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mutex_lock(&xen_pcpu_lock);
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while (!err && (cpu <= max_cpu)) {
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err = sync_pcpu(cpu, &max_cpu);
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cpu++;
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}
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if (err)
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list_for_each_entry_safe(pcpu, tmp, &xen_pcpus, list)
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unregister_and_remove_pcpu(pcpu);
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mutex_unlock(&xen_pcpu_lock);
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return err;
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}
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static void xen_pcpu_work_fn(struct work_struct *work)
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{
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xen_sync_pcpus();
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}
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static DECLARE_WORK(xen_pcpu_work, xen_pcpu_work_fn);
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static irqreturn_t xen_pcpu_interrupt(int irq, void *dev_id)
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{
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schedule_work(&xen_pcpu_work);
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return IRQ_HANDLED;
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}
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static int __init xen_pcpu_init(void)
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{
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int irq, ret;
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if (!xen_initial_domain())
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return -ENODEV;
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irq = bind_virq_to_irqhandler(VIRQ_PCPU_STATE, 0,
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xen_pcpu_interrupt, 0,
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"xen-pcpu", NULL);
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if (irq < 0) {
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pr_warning(XEN_PCPU "Failed to bind pcpu virq\n");
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return irq;
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}
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ret = subsys_system_register(&xen_pcpu_subsys, NULL);
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if (ret) {
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pr_warning(XEN_PCPU "Failed to register pcpu subsys\n");
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goto err1;
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}
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ret = xen_sync_pcpus();
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if (ret) {
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pr_warning(XEN_PCPU "Failed to sync pcpu info\n");
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goto err2;
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}
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return 0;
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err2:
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bus_unregister(&xen_pcpu_subsys);
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err1:
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unbind_from_irqhandler(irq, NULL);
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return ret;
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}
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arch_initcall(xen_pcpu_init);
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@ -314,6 +314,13 @@ struct xenpf_pcpuinfo {
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};
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DEFINE_GUEST_HANDLE_STRUCT(xenpf_pcpuinfo);
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#define XENPF_cpu_online 56
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#define XENPF_cpu_offline 57
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struct xenpf_cpu_ol {
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uint32_t cpuid;
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};
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DEFINE_GUEST_HANDLE_STRUCT(xenpf_cpu_ol);
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struct xen_platform_op {
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uint32_t cmd;
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uint32_t interface_version; /* XENPF_INTERFACE_VERSION */
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@ -330,6 +337,7 @@ struct xen_platform_op {
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struct xenpf_getidletime getidletime;
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struct xenpf_set_processor_pminfo set_pminfo;
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struct xenpf_pcpuinfo pcpu_info;
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struct xenpf_cpu_ol cpu_ol;
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uint8_t pad[128];
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} u;
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};
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@ -80,6 +80,7 @@
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#define VIRQ_CONSOLE 2 /* (DOM0) Bytes received on emergency console. */
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#define VIRQ_DOM_EXC 3 /* (DOM0) Exceptional event for some domain. */
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#define VIRQ_DEBUGGER 6 /* (DOM0) A domain has paused for debugging. */
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#define VIRQ_PCPU_STATE 9 /* (DOM0) PCPU state changed */
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/* Architecture-specific VIRQ definitions. */
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#define VIRQ_ARCH_0 16
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