linux/drivers/xen/pcpu.c
Roger Pau Monne 073828e954 ACPI: processor: Fix evaluating _PDC method when running as Xen dom0
In ACPI systems, the OS can direct power management, as opposed to the
firmware.  This OS-directed Power Management is called OSPM.  Part of
telling the firmware that the OS going to direct power management is
making ACPI "_PDC" (Processor Driver Capabilities) calls.  These _PDC
methods must be evaluated for every processor object.  If these _PDC
calls are not completed for every processor it can lead to
inconsistency and later failures in things like the CPU frequency
driver.

In a Xen system, the dom0 kernel is responsible for system-wide power
management.  The dom0 kernel is in charge of OSPM.  However, the
number of CPUs available to dom0 can be different than the number of
CPUs physically present on the system.

This leads to a problem: the dom0 kernel needs to evaluate _PDC for
all the processors, but it can't always see them.

In dom0 kernels, ignore the existing ACPI method for determining if a
processor is physically present because it might not be accurate.
Instead, ask the hypervisor for this information.

Fix this by introducing a custom function to use when running as Xen
dom0 in order to check whether a processor object matches a CPU that's
online.  Such checking is done using the existing information fetched
by the Xen pCPU subsystem, extending it to also store the ACPI ID.

This ensures that _PDC method gets evaluated for all physically online
CPUs, regardless of the number of CPUs made available to dom0.

Fixes: 5d554a7bb0 ("ACPI: processor: add internal processor_physically_present()")
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2023-03-22 19:36:31 +01:00

404 lines
8.8 KiB
C

/******************************************************************************
* pcpu.c
* Management physical cpu in dom0, get pcpu info and provide sys interface
*
* Copyright (c) 2012 Intel Corporation
* Author: Liu, Jinsong <jinsong.liu@intel.com>
* Author: Jiang, Yunhong <yunhong.jiang@intel.com>
*
* 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.
*/
#define pr_fmt(fmt) "xen_cpu: " fmt
#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/acpi.h>
#include <xen/xenbus.h>
#include <xen/events.h>
#include <xen/interface/platform.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>
/*
* @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 acpi_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_platform_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_platform_op(&op);
}
static ssize_t online_show(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 online_store(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_RW(online);
static struct attribute *pcpu_dev_attrs[] = {
&dev_attr_online.attr,
NULL
};
static umode_t pcpu_dev_is_visible(struct kobject *kobj,
struct attribute *attr, int idx)
{
struct device *dev = kobj_to_dev(kobj);
/*
* 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.
*/
return dev->id ? attr->mode : 0;
}
static const struct attribute_group pcpu_dev_group = {
.attrs = pcpu_dev_attrs,
.is_visible = pcpu_dev_is_visible,
};
static const struct attribute_group *pcpu_dev_groups[] = {
&pcpu_dev_group,
NULL
};
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;
/* 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;
dev->groups = pcpu_dev_groups;
err = device_register(dev);
if (err) {
put_device(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->acpi_id = info->acpi_id;
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_warn("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_platform_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) {
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_warn("Failed to bind pcpu virq\n");
return irq;
}
ret = subsys_system_register(&xen_pcpu_subsys, NULL);
if (ret) {
pr_warn("Failed to register pcpu subsys\n");
goto err1;
}
ret = xen_sync_pcpus();
if (ret) {
pr_warn("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);
#ifdef CONFIG_ACPI
bool __init xen_processor_present(uint32_t acpi_id)
{
const struct pcpu *pcpu;
bool online = false;
mutex_lock(&xen_pcpu_lock);
list_for_each_entry(pcpu, &xen_pcpus, list)
if (pcpu->acpi_id == acpi_id) {
online = pcpu->flags & XEN_PCPU_FLAGS_ONLINE;
break;
}
mutex_unlock(&xen_pcpu_lock);
return online;
}
#endif