Re: [PATCH 3/3] Xen pad logic and notification

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Fri, Feb 17, 2012 at 08:58:38AM +0000, Liu, Jinsong wrote:
> >From fee39804d2634dfba7b369dc82dac19b57400f84 Mon Sep 17 00:00:00 2001
> From: Liu, Jinsong <jinsong.liu@intel.com>
> Date: Sat, 18 Feb 2012 00:46:29 +0800
> Subject: [PATCH 3/3] Xen pad logic and notification
> 
> This patch implement Xen pad logic, and when getting pad device
> notification, it hypercalls to Xen hypervisor for core parking.

CC-ing linux-acpi@vger.kernel.org and Len Brown.

> 
> Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>
> ---
>  drivers/xen/xen_acpi_pad.c       |  189 ++++++++++++++++++++++++++++++++++++++
>  include/xen/interface/platform.h |   14 +++
>  2 files changed, 203 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/xen/xen_acpi_pad.c b/drivers/xen/xen_acpi_pad.c
> index 63ab2fb..ba66d51 100644
> --- a/drivers/xen/xen_acpi_pad.c
> +++ b/drivers/xen/xen_acpi_pad.c
> @@ -1,8 +1,197 @@
> +/*
> + * xen_acpi_pad.c - Xen pad interface
> + *
> + * Copyright (c) 2012, Intel Corporation.
> + *    Author: Liu, Jinsong <jinsong.liu@intel.com>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/types.h>
> +#include <acpi/acpi_bus.h>
> +#include <acpi/acpi_drivers.h>
> +
> +#include <asm/xen/hypercall.h>
> +
> +#define ACPI_PROCESSOR_AGGREGATOR_CLASS "xen_acpi_pad"
> +#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Xen Processor Aggregator"
> +#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
> +static DEFINE_MUTEX(xen_cpu_lock);
> +
> +static int xen_acpi_pad_idle_cpus(int *num_cpus)
> +{
> +	int ret;
> +
> +	struct xen_platform_op op = {
> +		.cmd = XENPF_core_parking,
> +		.interface_version = XENPF_INTERFACE_VERSION,
> +	};
> +
> +	/* set cpu nums expected to be idled */
> +	op.u.core_parking.type = XEN_CORE_PARKING_SET;
> +	op.u.core_parking.idle_nums = (uint32_t)*num_cpus;
> +	ret = HYPERVISOR_dom0_op(&op);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * get cpu nums actually be idled
> +	 * cannot get it by using hypercall once (shared with _SET)
> +	 * because of the characteristic of Xen continue_hypercall_on_cpu
> +	 */
> +	op.u.core_parking.type = XEN_CORE_PARKING_GET;
> +	ret = HYPERVISOR_dom0_op(&op);
> +	if (ret)
> +		return ret;
> +
> +	*num_cpus = op.u.core_parking.idle_nums;
> +	return 0;
> +}
> +
> +/*
> + * Query firmware how many CPUs should be idle
> + * return -1 on failure
> + */
> +static int xen_acpi_pad_pur(acpi_handle handle)
> +{
> +	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
> +	union acpi_object *package;
> +	int num = -1;
> +
> +	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
> +		return num;
> +
> +	if (!buffer.length || !buffer.pointer)
> +		return num;
> +
> +	package = buffer.pointer;
> +
> +	if (package->type == ACPI_TYPE_PACKAGE &&
> +		package->package.count == 2 &&
> +		package->package.elements[0].integer.value == 1) /* rev 1 */
> +
> +		num = package->package.elements[1].integer.value;
> +
> +	kfree(buffer.pointer);
> +	return num;
> +}
> +
> +/* Notify firmware how many CPUs are idle */
> +static void xen_acpi_pad_ost(acpi_handle handle, int stat,
> +	uint32_t idle_cpus)
> +{
> +	union acpi_object params[3] = {
> +		{.type = ACPI_TYPE_INTEGER,},
> +		{.type = ACPI_TYPE_INTEGER,},
> +		{.type = ACPI_TYPE_BUFFER,},
> +	};
> +	struct acpi_object_list arg_list = {3, params};
> +
> +	params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY;
> +	params[1].integer.value =  stat;
> +	params[2].buffer.length = 4;
> +	params[2].buffer.pointer = (void *)&idle_cpus;
> +	acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
> +}
> +
> +static void xen_acpi_pad_handle_notify(acpi_handle handle)
> +{
> +	int ret, num_cpus;
> +
> +	mutex_lock(&xen_cpu_lock);
> +	num_cpus = xen_acpi_pad_pur(handle);
> +	if (num_cpus < 0) {
> +		mutex_unlock(&xen_cpu_lock);
> +		return;
> +	}
> +
> +	ret = xen_acpi_pad_idle_cpus(&num_cpus);
> +	if (ret) {
> +		mutex_unlock(&xen_cpu_lock);
> +		return;
> +	}
> +
> +	xen_acpi_pad_ost(handle, 0, num_cpus);
> +	mutex_unlock(&xen_cpu_lock);
> +}
> +
> +static void xen_acpi_pad_notify(acpi_handle handle, u32 event,
> +	void *data)
> +{
> +	switch (event) {
> +	case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
> +		xen_acpi_pad_handle_notify(handle);
> +		break;
> +	default:
> +		printk(KERN_WARNING "Unsupported event [0x%x]\n", event);
> +		break;
> +	}
> +}
> +
> +static int xen_acpi_pad_add(struct acpi_device *device)
> +{
> +	acpi_status status;
> +
> +	strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
> +	strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
> +
> +	status = acpi_install_notify_handler(device->handle,
> +		 ACPI_DEVICE_NOTIFY, xen_acpi_pad_notify, device);
> +	if (ACPI_FAILURE(status))
> +		return -ENODEV;
> +
> +	return 0;
> +}
> +
> +static int xen_acpi_pad_remove(struct acpi_device *device,
> +	int type)
> +{
> +	int num_cpus = 0;
> +
> +	mutex_lock(&xen_cpu_lock);
> +	xen_acpi_pad_idle_cpus(&num_cpus);
> +	mutex_unlock(&xen_cpu_lock);
> +
> +	acpi_remove_notify_handler(device->handle,
> +		ACPI_DEVICE_NOTIFY, xen_acpi_pad_notify);
> +	return 0;
> +}
> +
> +static const struct acpi_device_id xen_pad_device_ids[] = {
> +	{"ACPI000C", 0},
> +	{"", 0},
> +};
> +
> +static struct acpi_driver xen_acpi_pad_driver = {
> +	.name = "xen_processor_aggregator",
> +	.class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
> +	.ids = xen_pad_device_ids,
> +	.ops = {
> +		.add = xen_acpi_pad_add,
> +		.remove = xen_acpi_pad_remove,
> +	},
> +};
> +
>  int xen_acpi_pad_init(void)
>  {
> +#ifdef CONFIG_ACPI_PROCESSOR_AGGREGATOR

How does that work when the the driver is booted under baremetal? Won't
it kick out the native ACPI_PROCESSOR_AGGREGATOR_CLASS (acpi_pad.c) ?

What about if the other ACPI_PROCESSOR_AGGREGATOR_CLASS gets called first?
Won't this fail?

Or is the acpi_bus_register_driver smart enough to process more than one
ACPI bus device?

> +	return acpi_bus_register_driver(&xen_acpi_pad_driver);
> +#else
>  	return 0;
> +#endif
>  }
>  
>  void xen_acpi_pad_exit(void)
>  {
> +#ifdef CONFIG_ACPI_PROCESSOR_AGGREGATOR
> +	acpi_bus_unregister_driver(&xen_acpi_pad_driver);
> +#endif
>  }
> diff --git a/include/xen/interface/platform.h b/include/xen/interface/platform.h
> index c168468..56ec72a 100644
> --- a/include/xen/interface/platform.h
> +++ b/include/xen/interface/platform.h
> @@ -297,6 +297,19 @@ struct xenpf_set_processor_pminfo {
>  };
>  DEFINE_GUEST_HANDLE_STRUCT(xenpf_set_processor_pminfo);
>  
> +#define XENPF_core_parking      60
> +
> +#define XEN_CORE_PARKING_SET    1
> +#define XEN_CORE_PARKING_GET    2
> +struct xenpf_core_parking {
> +	/* IN variables */
> +	uint32_t type;
> +	/* IN variables:  set cpu nums expected to be idled */
> +	/* OUT variables: get cpu nums actually be idled */
> +	uint32_t idle_nums;
> +};
> +DEFINE_GUEST_HANDLE_STRUCT(xenpf_core_parking);
> +
>  struct xen_platform_op {
>  	uint32_t cmd;
>  	uint32_t interface_version; /* XENPF_INTERFACE_VERSION */
> @@ -312,6 +325,7 @@ struct xen_platform_op {
>  		struct xenpf_change_freq       change_freq;
>  		struct xenpf_getidletime       getidletime;
>  		struct xenpf_set_processor_pminfo set_pminfo;
> +		struct xenpf_core_parking      core_parking;
>  		uint8_t                        pad[128];
>  	} u;
>  };
> -- 
> 1.7.1