Re: [Xen-devel] [PATCH 1/3] PAD helper for native and paravirt platform

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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@xxxxxxxxx>
> > 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@xxxxxxxxx>
> > ---
> >  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?

> >  /* 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@xxxxxxxxx>
> > + *
> > + *  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
> 
> 
> 
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