Re: [PATCH 2/2] efi: Fix efi_power_off() not being run before acpi_power_off() when necessary

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 7/8/22 18:37, Ard Biesheuvel wrote:
> On Fri, 8 Jul 2022 at 15:14, Hans de Goede <hdegoede@redhat.com> wrote:
>>
>> Commit 98f30d0ecf79 ("ACPI: power: Switch to sys-off handler API")
>> switched the ACPI sleep code from directly setting the old global
>> pm_power_off handler to using the new register_sys_off_handler()
>> mechanism with a priority of SYS_OFF_PRIO_FIRMWARE.
>>
>> This is a problem when the old global pm_power_off handler would later
>> be overwritten, such as done by the late_initcall(efi_shutdown_init):
>>
>>         if (efi_poweroff_required())
>>                 pm_power_off = efi_power_off;
>>
>> The old global pm_power_off handler gets run with a priority of
>> SYS_OFF_PRIO_DEFAULT which is lower then SYS_OFF_PRIO_FIRMWARE, causing
>> acpi_power_off() to run first, changing the behavior from before
>> the ACPI sleep code switched to the new register_sys_off_handler().
>>
>> Switch the registering of efi_power_off over to register_sys_off_handler()
>> with a priority of SYS_OFF_PRIO_FIRMWARE + 1 so that it will run before
>> acpi_power_off() as before.
>>
>> Note since the new sys-off-handler code will try all handlers in
>> priority order, there is no more need for the EFI code to store and
>> call the original pm_power_off handler.
>>
>> Fixes: 98f30d0ecf79 ("ACPI: power: Switch to sys-off handler API")
>> Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> 
> Acked-by: Ard Biesheuvel <ardb@kernel.org>

Thanks, I'll include this in my next fixes pull-req for 5.19.

Regards,

Hans


> 
> Note that, as far as I know, this should only affect x86 even though
> this is generic EFI code, and arm64 also supports ACPI boot, but it
> doesn't use ACPI for poweroff/reboot etc
> 
>> ---
>>  drivers/firmware/efi/reboot.c | 21 +++++++++++----------
>>  1 file changed, 11 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/firmware/efi/reboot.c b/drivers/firmware/efi/reboot.c
>> index 73089a24f04b..ceae84c19d22 100644
>> --- a/drivers/firmware/efi/reboot.c
>> +++ b/drivers/firmware/efi/reboot.c
>> @@ -6,7 +6,7 @@
>>  #include <linux/efi.h>
>>  #include <linux/reboot.h>
>>
>> -static void (*orig_pm_power_off)(void);
>> +static struct sys_off_handler *efi_sys_off_handler;
>>
>>  int efi_reboot_quirk_mode = -1;
>>
>> @@ -51,15 +51,11 @@ bool __weak efi_poweroff_required(void)
>>         return false;
>>  }
>>
>> -static void efi_power_off(void)
>> +static int efi_power_off(struct sys_off_data *data)
>>  {
>>         efi.reset_system(EFI_RESET_SHUTDOWN, EFI_SUCCESS, 0, NULL);
>> -       /*
>> -        * The above call should not return, if it does fall back to
>> -        * the original power off method (typically ACPI poweroff).
>> -        */
>> -       if (orig_pm_power_off)
>> -               orig_pm_power_off();
>> +
>> +       return NOTIFY_DONE;
>>  }
>>
>>  static int __init efi_shutdown_init(void)
>> @@ -68,8 +64,13 @@ static int __init efi_shutdown_init(void)
>>                 return -ENODEV;
>>
>>         if (efi_poweroff_required()) {
>> -               orig_pm_power_off = pm_power_off;
>> -               pm_power_off = efi_power_off;
>> +               /* SYS_OFF_PRIO_FIRMWARE + 1 so that it runs before acpi_power_off */
>> +               efi_sys_off_handler =
>> +                       register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
>> +                                                SYS_OFF_PRIO_FIRMWARE + 1,
>> +                                                efi_power_off, NULL);
>> +               if (IS_ERR(efi_sys_off_handler))
>> +                       return PTR_ERR(efi_sys_off_handler);
>>         }
>>
>>         return 0;
>> --
>> 2.36.0
>>
>