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Date:	Sun, 19 Feb 2012 12:14:51 +0000
From:	"Liu, Jinsong" <jinsong.liu@...el.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"keir.xen@...il.com" <keir.xen@...il.com>,
	Jan Beulich <JBeulich@...e.com>,
	"Li, Shaohua" <shaohua.li@...el.com>,
	"lenb@...nel.org" <lenb@...nel.org>
Subject: RE: [Xen-devel] [PATCH 1/3] PAD helper for native and paravirt
 platform

Konrad Rzeszutek Wilk wrote:
> On Fri, Feb 17, 2012 at 09:29:09AM -0500, Konrad Rzeszutek Wilk wrote:
>> On Fri, Feb 17, 2012 at 08:56:43AM +0000, Liu, Jinsong wrote:
>>>> From f66a2df1392bbe69426387657a220177be50d58a Mon Sep 17 00:00:00
>>>> 2001 
>>> From: Liu, Jinsong <jinsong.liu@...el.com>
>>> Date: Fri, 10 Feb 2012 20:32:50 +0800
>>> Subject: [PATCH 1/3] PAD helper for native and paravirt platform
>>> 
>>> This patch is PAD (Processor Aggregator Device) helper.
>>> It provides a native interface for natvie platform, and a template
>>> for paravirt platform, so that os can implicitly hook to proper ops
>>> accordingly. 
>>> The paravirt template will further redirect to Xen pv ops in later
>>>  patch for Xen core parking.
>> 
>> You need to CC the ACPI maintainer and the acpi mailing on this
>> patch. I did that for you in the CC. 
>> 
>> 
>>> 
>>> Signed-off-by: Liu, Jinsong <jinsong.liu@...el.com> ---
>>>  arch/x86/include/asm/paravirt.h       |   10 +++++
>>>  arch/x86/include/asm/paravirt_types.h |    7 ++++
>>>  arch/x86/kernel/paravirt.c            |    9 +++++
>>>  drivers/acpi/acpi_pad.c               |   15 +++-----
>>>  include/acpi/acpi_pad.h               |   61
>>>  +++++++++++++++++++++++++++++++++ 5 files changed, 93
>>>  insertions(+), 9 deletions(-) create mode 100644
>>> include/acpi/acpi_pad.h 
>>> 
>>> diff --git a/arch/x86/include/asm/paravirt.h
>>> b/arch/x86/include/asm/paravirt.h 
>>> index a7d2db9..02e6df0 100644
>>> --- a/arch/x86/include/asm/paravirt.h
>>> +++ b/arch/x86/include/asm/paravirt.h
>>> @@ -54,6 +54,16 @@ static inline unsigned long read_cr0(void)
>>>  	return PVOP_CALL0(unsigned long, pv_cpu_ops.read_cr0);  }
>>> 
>>> +static inline int __acpi_pad_init(void)
>>> +{
>>> +	return PVOP_CALL0(int, pv_pad_ops.acpi_pad_init); +}
>>> +
>>> +static inline void __acpi_pad_exit(void)
>>> +{
>>> +	PVOP_VCALL0(pv_pad_ops.acpi_pad_exit);
>>> +}
>>> +
>>>  static inline void write_cr0(unsigned long x)
>>>  {
>>>  	PVOP_VCALL1(pv_cpu_ops.write_cr0, x);
>>> diff --git a/arch/x86/include/asm/paravirt_types.h
>>> b/arch/x86/include/asm/paravirt_types.h index 8e8b9a4..61e20de
>>> 100644 --- a/arch/x86/include/asm/paravirt_types.h +++
>>> b/arch/x86/include/asm/paravirt_types.h @@ -336,6 +336,11 @@ struct
>>>  	pv_lock_ops { void (*spin_unlock)(struct arch_spinlock *lock);
>>>  };
>>> 
>>> +struct pv_pad_ops {
>>> +	int (*acpi_pad_init)(void);
>>> +	void (*acpi_pad_exit)(void);
>>> +};
>>> +
> 
> Looking at this a bit closer I am not sure why you choose the paravirt
> interface for this? There is another one - the x86 that could have
> been 
> choosen. Or introduce a new one that is specific to ACPI.
> 
> I am curious - what was the reason for using the paravirt interface?
> I understand it does get the job done, but it seems a bit overkill
> when something simple could have been used?
> 

It uses paravirt interface to avoid some code like 'xen_...' in native code path (acpi_pad.c).
I'm not quite sure what does 'x86' here mean? Adding 2 fields (acpi_pad_init/exit) in arch/x86/xen/enlighten.c --> xen_cpu_ops? seems it's much simpler.

Thanks,
Jinsong

>>>  /* This contains all the paravirt structures: we get a convenient
>>>   * number for each function using the offset which we use to
>>> indicate 
>>>   * what to patch. */
>>> @@ -347,6 +352,7 @@ struct paravirt_patch_template {
>>>  	struct pv_apic_ops pv_apic_ops;
>>>  	struct pv_mmu_ops pv_mmu_ops;
>>>  	struct pv_lock_ops pv_lock_ops;
>>> +	struct pv_pad_ops pv_pad_ops;
>>>  };
>>> 
>>>  extern struct pv_info pv_info;
>>> @@ -357,6 +363,7 @@ extern struct pv_irq_ops pv_irq_ops;
>>>  extern struct pv_apic_ops pv_apic_ops;
>>>  extern struct pv_mmu_ops pv_mmu_ops;
>>>  extern struct pv_lock_ops pv_lock_ops;
>>> +extern struct pv_pad_ops pv_pad_ops;
>>> 
>>>  #define PARAVIRT_PATCH(x)					\
>>>  	(offsetof(struct paravirt_patch_template, x) / sizeof(void *))
>>> diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
>>> index d90272e..ec778f6 100644
>>> --- a/arch/x86/kernel/paravirt.c
>>> +++ b/arch/x86/kernel/paravirt.c
>>> @@ -38,6 +38,8 @@
>>>  #include <asm/tlbflush.h>
>>>  #include <asm/timer.h>
>>> 
>>> +#include <acpi/acpi_pad.h>
>>> +
>>>  /* nop stub */
>>>  void _paravirt_nop(void)
>>>  {
>>> @@ -132,6 +134,7 @@ static void *get_call_destination(u8 type)
>>>  #ifdef CONFIG_PARAVIRT_SPINLOCKS
>>>  		.pv_lock_ops = pv_lock_ops,
>>>  #endif
>>> +		.pv_pad_ops = pv_pad_ops,
>>>  	};
>>>  	return *((void **)&tmpl + type);
>>>  }
>>> @@ -480,9 +483,15 @@ struct pv_mmu_ops pv_mmu_ops = {
>>>  	.set_fixmap = native_set_fixmap,
>>>  };
>>> 
>>> +struct pv_pad_ops pv_pad_ops = {
>>> +	.acpi_pad_init = native_acpi_pad_init,
>>> +	.acpi_pad_exit = native_acpi_pad_exit,
>>> +};
>>> +
>>>  EXPORT_SYMBOL_GPL(pv_time_ops);
>>>  EXPORT_SYMBOL    (pv_cpu_ops);
>>>  EXPORT_SYMBOL    (pv_mmu_ops);
>>>  EXPORT_SYMBOL_GPL(pv_apic_ops);
>>>  EXPORT_SYMBOL_GPL(pv_info);
>>>  EXPORT_SYMBOL    (pv_irq_ops);
>>> +EXPORT_SYMBOL_GPL(pv_pad_ops);
>>> diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
>>> index a43fa1a..3f0fd27 100644
>>> --- a/drivers/acpi/acpi_pad.c
>>> +++ b/drivers/acpi/acpi_pad.c
>>> @@ -30,6 +30,7 @@
>>>  #include <linux/slab.h>
>>>  #include <acpi/acpi_bus.h>
>>>  #include <acpi/acpi_drivers.h>
>>> +#include <acpi/acpi_pad.h>
>>>  #include <asm/mwait.h>
>>> 
>>>  #define ACPI_PROCESSOR_AGGREGATOR_CLASS	"acpi_pad" @@ -37,14
>>>  +38,14 @@ #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
>>>  static DEFINE_MUTEX(isolated_cpus_lock);
>>> 
>>> -static unsigned long power_saving_mwait_eax;
>>> +unsigned long power_saving_mwait_eax;
>>> 
>>>  static unsigned char tsc_detected_unstable;
>>>  static unsigned char tsc_marked_unstable;
>>>  static unsigned char lapic_detected_unstable;
>>>  static unsigned char lapic_marked_unstable;
>>> 
>>> -static void power_saving_mwait_init(void)
>>> +void power_saving_mwait_init(void)
>>>  {
>>>  	unsigned int eax, ebx, ecx, edx;
>>>  	unsigned int highest_cstate = 0;
>>> @@ -500,7 +501,7 @@ static const struct acpi_device_id
>>>  pad_device_ids[] = {  }; MODULE_DEVICE_TABLE(acpi, pad_device_ids);
>>> 
>>> -static struct acpi_driver acpi_pad_driver = {
>>> +struct acpi_driver acpi_pad_driver = {
>>>  	.name = "processor_aggregator",
>>>  	.class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
>>>  	.ids = pad_device_ids,
>>> @@ -512,16 +513,12 @@ static struct acpi_driver acpi_pad_driver = {
>>> 
>>>  static int __init acpi_pad_init(void)
>>>  {
>>> -	power_saving_mwait_init();
>>> -	if (power_saving_mwait_eax == 0)
>>> -		return -EINVAL;
>>> -
>>> -	return acpi_bus_register_driver(&acpi_pad_driver); +	return
>>>  __acpi_pad_init(); }
>>> 
>>>  static void __exit acpi_pad_exit(void)
>>>  {
>>> -	acpi_bus_unregister_driver(&acpi_pad_driver);
>>> +	__acpi_pad_exit();
>>>  }
>>> 
>>>  module_init(acpi_pad_init);
>>> diff --git a/include/acpi/acpi_pad.h b/include/acpi/acpi_pad.h
>>> new file mode 100644
>>> index 0000000..1a1471d
>>> --- /dev/null
>>> +++ b/include/acpi/acpi_pad.h
>>> @@ -0,0 +1,61 @@
>>> +/*
>>> + *  acpi_pad.h - pad device helper for native and paravirt
>>> platform + * + *  Copyright (C) 2012, Intel Corporation.
>>> + *     Author: Liu, Jinsong <jinsong.liu@...el.com> + *
>>> + *  This program is free software; you can redistribute it and/or
>>> modify + *  it under the terms of the GNU General Public License as
>>> published by + *  the Free Software Foundation; either version 2 of
>>> the License, or (at + *  your option) any later version.
>>> + *
>>> + *  This program is distributed in the hope that 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.
>>> + */
>>> +
>>> +#ifndef __ACPI_PAD_H__
>>> +#define __ACPI_PAD_H__
>>> +
>>> +#include <acpi/acpi_bus.h>
>>> +
>>> +extern unsigned long power_saving_mwait_eax;
>>> +extern struct acpi_driver acpi_pad_driver;
>>> +extern void power_saving_mwait_init(void);
>>> +
>>> +static inline int native_acpi_pad_init(void)
>>> +{
>>> +#ifdef CONFIG_ACPI_PROCESSOR_AGGREGATOR
>>> +	power_saving_mwait_init();
>>> +	if (power_saving_mwait_eax == 0)
>>> +		return -EINVAL;
>>> +
>>> +	return acpi_bus_register_driver(&acpi_pad_driver); +#else
>>> +	return 0;
>>> +#endif
>>> +}
>>> +
>>> +static inline void native_acpi_pad_exit(void)
>>> +{
>>> +#ifdef CONFIG_ACPI_PROCESSOR_AGGREGATOR
>>> +	acpi_bus_unregister_driver(&acpi_pad_driver);
>>> +#endif
>>> +}
>>> +
>>> +#ifdef CONFIG_PARAVIRT
>>> +#include <asm/paravirt.h>
>>> +#else
>>> +static inline int __acpi_pad_init(void)
>>> +{
>>> +	return native_acpi_pad_init();
>>> +}
>>> +
>>> +static inline void __acpi_pad_exit(void)
>>> +{
>>> +	native_acpi_pad_exit();
>>> +}
>>> +#endif
>>> +
>>> +#endif /* __ACPI_PAD_H__ */
>>> --
>>> 1.7.1
>> 
>> 
>> 
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@...ts.xensource.com
>> http://lists.xensource.com/xen-devel

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