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 <hu...@cn.fujitsu.com>
> > > ---
> > > 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 0000000..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 <linux/kernel.h>
> > > +#include <linux/module.h>
> > > +#include <linux/init.h>
> > > +#include <linux/types.h>
> > > +#include <acpi/acpi_bus.h>
> > > +#include <acpi/acpi_drivers.h>
> > > +
> > > +MODULE_AUTHOR("Hu Tao <hu...@cn.fujitsu.com>");
> > > +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 because the pvpanic notifier is called with interrupts
disabled.
Suppose its safer to use an OUT instruction?
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