Re: [PATCH v17 RESEND] pvpanic: pvpanic device driver

2013-05-06 Thread Paolo Bonzini 
Il 06/05/2013 13:38, Marcelo Tosatti ha scritto:
> On Mon, May 06, 2013 at 11:39:35AM +0800, Hu Tao wrote:
>> On Fri, May 03, 2013 at 06:59:18PM -0300, Marcelo Tosatti wrote:
>>> On Fri, May 03, 2013 at 10:47:10AM +0800, Hu Tao wrote:
 pvpanic device is a qemu simulated device through which guest panic
 event is sent to host.

 Signed-off-by: Hu Tao 
 ---
  drivers/platform/x86/Kconfig   |   7 +++
  drivers/platform/x86/Makefile  |   2 +
  drivers/platform/x86/pvpanic.c | 115 
 +
  3 files changed, 124 insertions(+)
  create mode 100644 drivers/platform/x86/pvpanic.c

 diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
 index 3338437..527ed04 100644
 --- a/drivers/platform/x86/Kconfig
 +++ b/drivers/platform/x86/Kconfig
 @@ -781,4 +781,11 @@ config APPLE_GMUX
  graphics as well as the backlight. Currently only backlight
  control is supported by the driver.
  
 +config PVPANIC
 +  tristate "pvpanic device support"
 +  depends on ACPI
 +  ---help---
 +This driver provides support for pvpanic device, which is a qemu
 +simulated device through which guest panic event is sent to host.
 +
  endif # X86_PLATFORM_DEVICES
 diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
 index ace2b38..ef0ec74 100644
 --- a/drivers/platform/x86/Makefile
 +++ b/drivers/platform/x86/Makefile
 @@ -51,3 +51,5 @@ obj-$(CONFIG_INTEL_OAKTRAIL) += intel_oaktrail.o
  obj-$(CONFIG_SAMSUNG_Q10) += samsung-q10.o
  obj-$(CONFIG_APPLE_GMUX)  += apple-gmux.o
  obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
 +
 +obj-$(CONFIG_PVPANIC)   += pvpanic.o
 diff --git a/drivers/platform/x86/pvpanic.c 
 b/drivers/platform/x86/pvpanic.c
 new file mode 100644
 index 000..81c95ec
 --- /dev/null
 +++ b/drivers/platform/x86/pvpanic.c
 @@ -0,0 +1,115 @@
 +/*
 + *  pvpanic.c - pvpanic Device Support
 + *
 + *  Copyright (C) 2013 Fujitsu.
 + *
 + *  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.
 + *
 + *  You should have received a copy of the GNU General Public License
 + *  along with this program; if not, write to the Free Software
 + *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  
 02110-1301  USA
 + */
 +
 +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 +
 +#include 
 +#include 
 +#include 
 +#include 
 +#include 
 +#include 
 +
 +MODULE_AUTHOR("Hu Tao ");
 +MODULE_DESCRIPTION("pvpanic device driver");
 +MODULE_LICENSE("GPL");
 +
 +static int pvpanic_add(struct acpi_device *device);
 +static int pvpanic_remove(struct acpi_device *device);
 +
 +static const struct acpi_device_id pvpanic_device_ids[] = {
 +  { "QEMU0001", 0},
 +  { "", 0},
 +};
 +MODULE_DEVICE_TABLE(acpi, pvpanic_device_ids);
 +
 +#define PVPANIC_PANICKED  (1 << 0)
 +
 +static acpi_handle handle;
 +
 +static struct acpi_driver pvpanic_driver = {
 +  .name = "pvpanic",
 +  .class ="QEMU",
 +  .ids =  pvpanic_device_ids,
 +  .ops =  {
 +  .add =  pvpanic_add,
 +  .remove =   pvpanic_remove,
 +  },
 +  .owner =THIS_MODULE,
 +};
 +
 +static void
 +pvpanic_send_event(unsigned int event)
 +{
 +  union acpi_object arg;
 +  struct acpi_object_list arg_list;
 +
 +  if (!handle)
 +  return;
 +
 +  arg.type = ACPI_TYPE_INTEGER;
 +  arg.integer.value = event;
 +
 +  arg_list.count = 1;
 +  arg_list.pointer = &arg;
 +
 +  acpi_evaluate_object(handle, "WRPT", &arg_list, NULL);
 +}
>>>
>>> Is it safe to call acpi_evaluate_object from a panic notifier? For
>>> example:
>>>
>>> - Has it been confirmed that no code invoked via acpi_evaluate_object can 
>>> panic() ?
>>
>> Confirmed.
>>
>>> - acpi_ex_enter_interpreter grabs a mutex. Is that path ever used?
>>
>> Unfortunately yes. As I can tell, there are 2 places in the path to grab
>> a mutex: when searching the namespace for the method, and when executing
>> the method. I didn't find a non-blocking version of acpi_evaluate_object.
> 
> Then thats a bug becau

Re: [PATCH v17 RESEND] pvpanic: pvpanic device driver

2013-05-06 Thread Marcelo Tosatti 
On Mon, May 06, 2013 at 11:39:35AM +0800, Hu Tao wrote:
> On Fri, May 03, 2013 at 06:59:18PM -0300, Marcelo Tosatti wrote:
> > On Fri, May 03, 2013 at 10:47:10AM +0800, Hu Tao wrote:
> > > pvpanic device is a qemu simulated device through which guest panic
> > > event is sent to host.
> > > 
> > > Signed-off-by: Hu Tao 
> > > ---
> > >  drivers/platform/x86/Kconfig   |   7 +++
> > >  drivers/platform/x86/Makefile  |   2 +
> > >  drivers/platform/x86/pvpanic.c | 115 
> > > +
> > >  3 files changed, 124 insertions(+)
> > >  create mode 100644 drivers/platform/x86/pvpanic.c
> > > 
> > > diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> > > index 3338437..527ed04 100644
> > > --- a/drivers/platform/x86/Kconfig
> > > +++ b/drivers/platform/x86/Kconfig
> > > @@ -781,4 +781,11 @@ config APPLE_GMUX
> > > graphics as well as the backlight. Currently only backlight
> > > control is supported by the driver.
> > >  
> > > +config PVPANIC
> > > + tristate "pvpanic device support"
> > > + depends on ACPI
> > > + ---help---
> > > +   This driver provides support for pvpanic device, which is a qemu
> > > +   simulated device through which guest panic event is sent to host.
> > > +
> > >  endif # X86_PLATFORM_DEVICES
> > > diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> > > index ace2b38..ef0ec74 100644
> > > --- a/drivers/platform/x86/Makefile
> > > +++ b/drivers/platform/x86/Makefile
> > > @@ -51,3 +51,5 @@ obj-$(CONFIG_INTEL_OAKTRAIL)+= intel_oaktrail.o
> > >  obj-$(CONFIG_SAMSUNG_Q10)+= samsung-q10.o
> > >  obj-$(CONFIG_APPLE_GMUX) += apple-gmux.o
> > >  obj-$(CONFIG_CHROMEOS_LAPTOP)+= chromeos_laptop.o
> > > +
> > > +obj-$(CONFIG_PVPANIC)   += pvpanic.o
> > > diff --git a/drivers/platform/x86/pvpanic.c 
> > > b/drivers/platform/x86/pvpanic.c
> > > new file mode 100644
> > > index 000..81c95ec
> > > --- /dev/null
> > > +++ b/drivers/platform/x86/pvpanic.c
> > > @@ -0,0 +1,115 @@
> > > +/*
> > > + *  pvpanic.c - pvpanic Device Support
> > > + *
> > > + *  Copyright (C) 2013 Fujitsu.
> > > + *
> > > + *  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.
> > > + *
> > > + *  You should have received a copy of the GNU General Public License
> > > + *  along with this program; if not, write to the Free Software
> > > + *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  
> > > 02110-1301  USA
> > > + */
> > > +
> > > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> > > +
> > > +#include 
> > > +#include 
> > > +#include 
> > > +#include 
> > > +#include 
> > > +#include 
> > > +
> > > +MODULE_AUTHOR("Hu Tao ");
> > > +MODULE_DESCRIPTION("pvpanic device driver");
> > > +MODULE_LICENSE("GPL");
> > > +
> > > +static int pvpanic_add(struct acpi_device *device);
> > > +static int pvpanic_remove(struct acpi_device *device);
> > > +
> > > +static const struct acpi_device_id pvpanic_device_ids[] = {
> > > + { "QEMU0001", 0},
> > > + { "", 0},
> > > +};
> > > +MODULE_DEVICE_TABLE(acpi, pvpanic_device_ids);
> > > +
> > > +#define PVPANIC_PANICKED (1 << 0)
> > > +
> > > +static acpi_handle handle;
> > > +
> > > +static struct acpi_driver pvpanic_driver = {
> > > + .name = "pvpanic",
> > > + .class ="QEMU",
> > > + .ids =  pvpanic_device_ids,
> > > + .ops =  {
> > > + .add =  pvpanic_add,
> > > + .remove =   pvpanic_remove,
> > > + },
> > > + .owner =THIS_MODULE,
> > > +};
> > > +
> > > +static void
> > > +pvpanic_send_event(unsigned int event)
> > > +{
> > > + union acpi_object arg;
> > > + struct acpi_object_list arg_list;
> > > +
> > > + if (!handle)
> > > + return;
> > > +
> > > + arg.type = ACPI_TYPE_INTEGER;
> > > + arg.integer.value = event;
> > > +
> > > + arg_list.count = 1;
> > > + arg_list.pointer = &arg;
> > > +
> > > + acpi_evaluate_object(handle, "WRPT", &arg_list, NULL);
> > > +}
> > 
> > Is it safe to call acpi_evaluate_object from a panic notifier? For
> > example:
> > 
> > - Has it been confirmed that no code invoked via acpi_evaluate_object can 
> > panic() ?
> 
> Confirmed.
> 
> > - acpi_ex_enter_interpreter grabs a mutex. Is that path ever used?
> 
> Unfortunately yes. As I can tell, there are 2 places in the path to grab
> a mutex: when searching the namespace for the method, and when executing
> the method. I didn't find a non-blocking version of acpi

Re: [PATCH v17 RESEND] pvpanic: pvpanic device driver

2013-05-05 Thread Hu Tao 
On Fri, May 03, 2013 at 06:59:18PM -0300, Marcelo Tosatti wrote:
> On Fri, May 03, 2013 at 10:47:10AM +0800, Hu Tao wrote:
> > pvpanic device is a qemu simulated device through which guest panic
> > event is sent to host.
> > 
> > Signed-off-by: Hu Tao 
> > ---
> >  drivers/platform/x86/Kconfig   |   7 +++
> >  drivers/platform/x86/Makefile  |   2 +
> >  drivers/platform/x86/pvpanic.c | 115 
> > +
> >  3 files changed, 124 insertions(+)
> >  create mode 100644 drivers/platform/x86/pvpanic.c
> > 
> > diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> > index 3338437..527ed04 100644
> > --- a/drivers/platform/x86/Kconfig
> > +++ b/drivers/platform/x86/Kconfig
> > @@ -781,4 +781,11 @@ config APPLE_GMUX
> >   graphics as well as the backlight. Currently only backlight
> >   control is supported by the driver.
> >  
> > +config PVPANIC
> > +   tristate "pvpanic device support"
> > +   depends on ACPI
> > +   ---help---
> > + This driver provides support for pvpanic device, which is a qemu
> > + simulated device through which guest panic event is sent to host.
> > +
> >  endif # X86_PLATFORM_DEVICES
> > diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> > index ace2b38..ef0ec74 100644
> > --- a/drivers/platform/x86/Makefile
> > +++ b/drivers/platform/x86/Makefile
> > @@ -51,3 +51,5 @@ obj-$(CONFIG_INTEL_OAKTRAIL)  += intel_oaktrail.o
> >  obj-$(CONFIG_SAMSUNG_Q10)  += samsung-q10.o
> >  obj-$(CONFIG_APPLE_GMUX)   += apple-gmux.o
> >  obj-$(CONFIG_CHROMEOS_LAPTOP)  += chromeos_laptop.o
> > +
> > +obj-$(CONFIG_PVPANIC)   += pvpanic.o
> > diff --git a/drivers/platform/x86/pvpanic.c b/drivers/platform/x86/pvpanic.c
> > new file mode 100644
> > index 000..81c95ec
> > --- /dev/null
> > +++ b/drivers/platform/x86/pvpanic.c
> > @@ -0,0 +1,115 @@
> > +/*
> > + *  pvpanic.c - pvpanic Device Support
> > + *
> > + *  Copyright (C) 2013 Fujitsu.
> > + *
> > + *  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.
> > + *
> > + *  You should have received a copy of the GNU General Public License
> > + *  along with this program; if not, write to the Free Software
> > + *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  
> > 02110-1301  USA
> > + */
> > +
> > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> > +
> > +#include 
> > +#include 
> > +#include 
> > +#include 
> > +#include 
> > +#include 
> > +
> > +MODULE_AUTHOR("Hu Tao ");
> > +MODULE_DESCRIPTION("pvpanic device driver");
> > +MODULE_LICENSE("GPL");
> > +
> > +static int pvpanic_add(struct acpi_device *device);
> > +static int pvpanic_remove(struct acpi_device *device);
> > +
> > +static const struct acpi_device_id pvpanic_device_ids[] = {
> > +   { "QEMU0001", 0},
> > +   { "", 0},
> > +};
> > +MODULE_DEVICE_TABLE(acpi, pvpanic_device_ids);
> > +
> > +#define PVPANIC_PANICKED   (1 << 0)
> > +
> > +static acpi_handle handle;
> > +
> > +static struct acpi_driver pvpanic_driver = {
> > +   .name = "pvpanic",
> > +   .class ="QEMU",
> > +   .ids =  pvpanic_device_ids,
> > +   .ops =  {
> > +   .add =  pvpanic_add,
> > +   .remove =   pvpanic_remove,
> > +   },
> > +   .owner =THIS_MODULE,
> > +};
> > +
> > +static void
> > +pvpanic_send_event(unsigned int event)
> > +{
> > +   union acpi_object arg;
> > +   struct acpi_object_list arg_list;
> > +
> > +   if (!handle)
> > +   return;
> > +
> > +   arg.type = ACPI_TYPE_INTEGER;
> > +   arg.integer.value = event;
> > +
> > +   arg_list.count = 1;
> > +   arg_list.pointer = &arg;
> > +
> > +   acpi_evaluate_object(handle, "WRPT", &arg_list, NULL);
> > +}
> 
> Is it safe to call acpi_evaluate_object from a panic notifier? For
> example:
> 
> - Has it been confirmed that no code invoked via acpi_evaluate_object can 
> panic() ?

Confirmed.

> - acpi_ex_enter_interpreter grabs a mutex. Is that path ever used?

Unfortunately yes. As I can tell, there are 2 places in the path to grab
a mutex: when searching the namespace for the method, and when executing
the method. I didn't find a non-blocking version of acpi_evaluate_object.

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Re: [PATCH v17 RESEND] pvpanic: pvpanic device driver

2013-05-03 Thread Marcelo Tosatti 
On Fri, May 03, 2013 at 10:47:10AM +0800, Hu Tao wrote:
> pvpanic device is a qemu simulated device through which guest panic
> event is sent to host.
> 
> Signed-off-by: Hu Tao 
> ---
>  drivers/platform/x86/Kconfig   |   7 +++
>  drivers/platform/x86/Makefile  |   2 +
>  drivers/platform/x86/pvpanic.c | 115 
> +
>  3 files changed, 124 insertions(+)
>  create mode 100644 drivers/platform/x86/pvpanic.c
> 
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 3338437..527ed04 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -781,4 +781,11 @@ config APPLE_GMUX
> graphics as well as the backlight. Currently only backlight
> control is supported by the driver.
>  
> +config PVPANIC
> + tristate "pvpanic device support"
> + depends on ACPI
> + ---help---
> +   This driver provides support for pvpanic device, which is a qemu
> +   simulated device through which guest panic event is sent to host.
> +
>  endif # X86_PLATFORM_DEVICES
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index ace2b38..ef0ec74 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -51,3 +51,5 @@ obj-$(CONFIG_INTEL_OAKTRAIL)+= intel_oaktrail.o
>  obj-$(CONFIG_SAMSUNG_Q10)+= samsung-q10.o
>  obj-$(CONFIG_APPLE_GMUX) += apple-gmux.o
>  obj-$(CONFIG_CHROMEOS_LAPTOP)+= chromeos_laptop.o
> +
> +obj-$(CONFIG_PVPANIC)   += pvpanic.o
> diff --git a/drivers/platform/x86/pvpanic.c b/drivers/platform/x86/pvpanic.c
> new file mode 100644
> index 000..81c95ec
> --- /dev/null
> +++ b/drivers/platform/x86/pvpanic.c
> @@ -0,0 +1,115 @@
> +/*
> + *  pvpanic.c - pvpanic Device Support
> + *
> + *  Copyright (C) 2013 Fujitsu.
> + *
> + *  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.
> + *
> + *  You should have received a copy of the GNU General Public License
> + *  along with this program; if not, write to the Free Software
> + *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  
> 02110-1301  USA
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +
> +MODULE_AUTHOR("Hu Tao ");
> +MODULE_DESCRIPTION("pvpanic device driver");
> +MODULE_LICENSE("GPL");
> +
> +static int pvpanic_add(struct acpi_device *device);
> +static int pvpanic_remove(struct acpi_device *device);
> +
> +static const struct acpi_device_id pvpanic_device_ids[] = {
> + { "QEMU0001", 0},
> + { "", 0},
> +};
> +MODULE_DEVICE_TABLE(acpi, pvpanic_device_ids);
> +
> +#define PVPANIC_PANICKED (1 << 0)
> +
> +static acpi_handle handle;
> +
> +static struct acpi_driver pvpanic_driver = {
> + .name = "pvpanic",
> + .class ="QEMU",
> + .ids =  pvpanic_device_ids,
> + .ops =  {
> + .add =  pvpanic_add,
> + .remove =   pvpanic_remove,
> + },
> + .owner =THIS_MODULE,
> +};
> +
> +static void
> +pvpanic_send_event(unsigned int event)
> +{
> + union acpi_object arg;
> + struct acpi_object_list arg_list;
> +
> + if (!handle)
> + return;
> +
> + arg.type = ACPI_TYPE_INTEGER;
> + arg.integer.value = event;
> +
> + arg_list.count = 1;
> + arg_list.pointer = &arg;
> +
> + acpi_evaluate_object(handle, "WRPT", &arg_list, NULL);
> +}

Is it safe to call acpi_evaluate_object from a panic notifier? For
example:

- Has it been confirmed that no code invoked via acpi_evaluate_object can 
panic() ?
- acpi_ex_enter_interpreter grabs a mutex. Is that path ever used?

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Re: [PATCH v17 RESEND] pvpanic: pvpanic device driver

2013-05-03 Thread Paolo Bonzini 
Il 03/05/2013 04:47, Hu Tao ha scritto:
> pvpanic device is a qemu simulated device through which guest panic
> event is sent to host.
> 
> Signed-off-by: Hu Tao 

Reviewed-by: Paolo Bonzini 

but you may reword the help message as hinted below.

Paolo

> ---
>  drivers/platform/x86/Kconfig   |   7 +++
>  drivers/platform/x86/Makefile  |   2 +
>  drivers/platform/x86/pvpanic.c | 115 
> +
>  3 files changed, 124 insertions(+)
>  create mode 100644 drivers/platform/x86/pvpanic.c
> 
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 3338437..527ed04 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -781,4 +781,11 @@ config APPLE_GMUX
> graphics as well as the backlight. Currently only backlight
> control is supported by the driver.
>  
> +config PVPANIC
> + tristate "pvpanic device support"
> + depends on ACPI
> + ---help---
> +   This driver provides support for pvpanic device, which is a qemu
> +   simulated device through which guest panic event is sent to host.

This driver provides support for the pvpanic device.  pvpanic is
a paravirtualized device provided by QEMU; it lets a virtual machine
(guest) communicate panic events to the host.

>  endif # X86_PLATFORM_DEVICES
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index ace2b38..ef0ec74 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -51,3 +51,5 @@ obj-$(CONFIG_INTEL_OAKTRAIL)+= intel_oaktrail.o
>  obj-$(CONFIG_SAMSUNG_Q10)+= samsung-q10.o
>  obj-$(CONFIG_APPLE_GMUX) += apple-gmux.o
>  obj-$(CONFIG_CHROMEOS_LAPTOP)+= chromeos_laptop.o
> +
> +obj-$(CONFIG_PVPANIC)   += pvpanic.o
> diff --git a/drivers/platform/x86/pvpanic.c b/drivers/platform/x86/pvpanic.c
> new file mode 100644
> index 000..81c95ec
> --- /dev/null
> +++ b/drivers/platform/x86/pvpanic.c
> @@ -0,0 +1,115 @@
> +/*
> + *  pvpanic.c - pvpanic Device Support
> + *
> + *  Copyright (C) 2013 Fujitsu.
> + *
> + *  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.
> + *
> + *  You should have received a copy of the GNU General Public License
> + *  along with this program; if not, write to the Free Software
> + *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  
> 02110-1301  USA
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +
> +MODULE_AUTHOR("Hu Tao ");
> +MODULE_DESCRIPTION("pvpanic device driver");
> +MODULE_LICENSE("GPL");
> +
> +static int pvpanic_add(struct acpi_device *device);
> +static int pvpanic_remove(struct acpi_device *device);
> +
> +static const struct acpi_device_id pvpanic_device_ids[] = {
> + { "QEMU0001", 0},
> + { "", 0},
> +};
> +MODULE_DEVICE_TABLE(acpi, pvpanic_device_ids);
> +
> +#define PVPANIC_PANICKED (1 << 0)
> +
> +static acpi_handle handle;
> +
> +static struct acpi_driver pvpanic_driver = {
> + .name = "pvpanic",
> + .class ="QEMU",
> + .ids =  pvpanic_device_ids,
> + .ops =  {
> + .add =  pvpanic_add,
> + .remove =   pvpanic_remove,
> + },
> + .owner =THIS_MODULE,
> +};
> +
> +static void
> +pvpanic_send_event(unsigned int event)
> +{
> + union acpi_object arg;
> + struct acpi_object_list arg_list;
> +
> + if (!handle)
> + return;
> +
> + arg.type = ACPI_TYPE_INTEGER;
> + arg.integer.value = event;
> +
> + arg_list.count = 1;
> + arg_list.pointer = &arg;
> +
> + acpi_evaluate_object(handle, "WRPT", &arg_list, NULL);
> +}
> +
> +static int
> +pvpanic_panic_notify(struct notifier_block *nb, unsigned long code,
> +  void *unused)
> +{
> + pvpanic_send_event(PVPANIC_PANICKED);
> + return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block pvpanic_panic_nb = {
> + .notifier_call = pvpanic_panic_notify,
> +};
> +
> +static int pvpanic_add(struct acpi_device *device)
> +{
> + acpi_status status;
> + u64 ret;
> +
> + status = acpi_evaluate_integer(device->handle, "_STA", NULL,
> +&ret);
> +
> + if (ACPI_FAILURE(status) || (ret & 0x0B) != 0x0B)
> + return -ENODEV;
> +
> + handle = device->handle;
> + atomic_notifier_chain_register(&panic_notifie