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Re: [PATCH] arm64: xen: Implement EFI reset_system callback

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  Re: [PATCH] arm64: xen: Implement EFI reset_system callback Stefano Stabellini <sstabellini@kernel.org> - 2017-04-18 20:40 +0200
    Re: [PATCH] arm64: xen: Implement EFI reset_system callback Stefano Stabellini <sstabellini@kernel.org> - 2017-04-18 20:50 +0200
      Re: [PATCH] arm64: xen: Implement EFI reset_system callback Juergen Gross <jgross@suse.com> - 2017-04-18 21:00 +0200
        Re: [PATCH] arm64: xen: Implement EFI reset_system callback Julien Grall <julien.grall@arm.com> - 2017-04-20 20:10 +0200
    Re: [PATCH] arm64: xen: Implement EFI reset_system callback Juergen Gross <jgross@suse.com> - 2017-04-18 20:50 +0200

#1625527 — Re: [PATCH] arm64: xen: Implement EFI reset_system callback

On Thu, 6 Apr 2017, Juergen Gross wrote:
> On 06/04/17 18:43, Daniel Kiper wrote:
> > On Thu, Apr 06, 2017 at 06:22:44PM +0200, Juergen Gross wrote:
> >> On 06/04/17 18:06, Daniel Kiper wrote:
> >>> Hi Julien,
> >>>
> >>> On Thu, Apr 06, 2017 at 04:39:13PM +0100, Julien Grall wrote:
> >>>> Hi Daniel,
> >>>>
> >>>> On 06/04/17 16:20, Daniel Kiper wrote:
> >>>>> On Thu, Apr 06, 2017 at 04:38:24PM +0200, Juergen Gross wrote:
> >>>>>> On 06/04/17 16:27, Daniel Kiper wrote:
> >>>>>>> On Thu, Apr 06, 2017 at 09:32:32AM +0100, Julien Grall wrote:
> >>>>>>>> Hi Juergen,
> >>>>>>>>
> >>>>>>>> On 06/04/17 07:23, Juergen Gross wrote:
> >>>>>>>>> On 05/04/17 21:49, Boris Ostrovsky wrote:
> >>>>>>>>>> On 04/05/2017 02:14 PM, Julien Grall wrote:
> >>>>>>>>>>> The x86 code has theoritically a similar issue, altought EFI does not
> >>>>>>>>>>> seem to be the preferred method. I have left it unimplemented on x86 and
> >>>>>>>>>>> CCed Linux Xen x86 maintainers to know their view here.
> >>>>>>>>>>
> >>>>>>>>>> (+Daniel)
> >>>>>>>>>>
> >>>>>>>>>> This could be a problem for x86 as well, at least theoretically.
> >>>>>>>>>> xen_machine_power_off() may call pm_power_off(), which is efi.reset_system.
> >>>>>>>>>>
> >>>>>>>>>> So I think we should have a similar routine there.
> >>>>>>>>>
> >>>>>>>>> +1
> >>>>>>>>>
> >>>>>>>>> I don't see any problem with such a routine added, in contrast to
> >>>>>>>>> potential "reboots" instead of power off without it.
> >>>>>>>>>
> >>>>>>>>> So I think this dummy xen_efi_reset_system() should be added to
> >>>>>>>>> drivers/xen/efi.c instead.
> >>>>>>>>
> >>>>>>>> I will resend the patch during day with xen_efi_reset_system moved
> >>>>>>>> to common code and implement the x86 counterpart (thought, I will
> >>>>>>>> not be able to test it).
> >>>>>>>
> >>>>>>> I think that this is ARM specific issue. On x86 machine_restart() calls
> >>>>>>> xen_restart(). Hence, everything works. So, I think that it should be
> >>>>>>> fixed only for ARM. Anyway, please CC me when you send a patch.
> >>>>>>
> >>>>>> What about xen_machine_power_off() (as stated in Boris' mail)?
> >>>>>
> >>>>> Guys what do you think about that:
> >>>>>
> >>>>> --- a/drivers/firmware/efi/reboot.c
> >>>>> +++ b/drivers/firmware/efi/reboot.c
> >>>>> @@ -55,7 +55,7 @@ static void efi_power_off(void)
> >>>>>
> >>>>> static int __init efi_shutdown_init(void)
> >>>>> {
> >>>>> -       if (!efi_enabled(EFI_RUNTIME_SERVICES))
> >>>>> +       if (!efi_enabled(EFI_RUNTIME_SERVICES) || efi_enabled(EFI_PARAVIRT))
> >>>>>                return -ENODEV;
> >>>>>
> >>>>>        if (efi_poweroff_required())
> >>>>>
> >>>>>
> >>>>> Julien, for ARM64 please take a look at arch/arm64/kernel/efi.c:efi_poweroff_required(void).
> >>>>>
> >>>>> I hope that tweaks for both files should solve our problem.
> >>>>
> >>>> This sounds good for power off (I haven't tried to power off DOM0
> >>>> yet). But this will not solve the restart problem (see
> >>>> machine_restart in arch/arm64/kernel/process.c) which call directly
> >>>> efi_reboot.
> >>>
> >>> Hmmm... It seems to me that efi.reset_system override with empty function
> >>> in arch/arm/xen/efi.c is the best solution. So, I see three patches here.
> >>> One for drivers/firmware/efi/reboot.c, one for arch/arm/xen/efi.c and one
> >>> for arch/arm64/kernel/efi.c. Does it make sense?
> >>
> >> I still think the empty function should be in drivers/xen/efi.c and we
> >> should use it in arch/x86/xen/efi.c, too.
> > 
> > If you wish we can go that way too. Though I thing that we should fix
> > drivers/firmware/efi/reboot.c:efi_shutdown_init() too. Just in case.
> 
> Sure, go ahead. I won't object.

For the Xen on ARM side, the original patch that started this thread
(20170405181417.15985-1-julien.grall@arm.com) is good to go, right?

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#1625537

On Tue, 18 Apr 2017, Juergen Gross wrote:
> On 18/04/17 20:37, Stefano Stabellini wrote:
> > On Thu, 6 Apr 2017, Juergen Gross wrote:
> >> On 06/04/17 18:43, Daniel Kiper wrote:
> >>> On Thu, Apr 06, 2017 at 06:22:44PM +0200, Juergen Gross wrote:
> >>>> On 06/04/17 18:06, Daniel Kiper wrote:
> >>>>> Hi Julien,
> >>>>>
> >>>>> On Thu, Apr 06, 2017 at 04:39:13PM +0100, Julien Grall wrote:
> >>>>>> Hi Daniel,
> >>>>>>
> >>>>>> On 06/04/17 16:20, Daniel Kiper wrote:
> >>>>>>> On Thu, Apr 06, 2017 at 04:38:24PM +0200, Juergen Gross wrote:
> >>>>>>>> On 06/04/17 16:27, Daniel Kiper wrote:
> >>>>>>>>> On Thu, Apr 06, 2017 at 09:32:32AM +0100, Julien Grall wrote:
> >>>>>>>>>> Hi Juergen,
> >>>>>>>>>>
> >>>>>>>>>> On 06/04/17 07:23, Juergen Gross wrote:
> >>>>>>>>>>> On 05/04/17 21:49, Boris Ostrovsky wrote:
> >>>>>>>>>>>> On 04/05/2017 02:14 PM, Julien Grall wrote:
> >>>>>>>>>>>>> The x86 code has theoritically a similar issue, altought EFI does not
> >>>>>>>>>>>>> seem to be the preferred method. I have left it unimplemented on x86 and
> >>>>>>>>>>>>> CCed Linux Xen x86 maintainers to know their view here.
> >>>>>>>>>>>>
> >>>>>>>>>>>> (+Daniel)
> >>>>>>>>>>>>
> >>>>>>>>>>>> This could be a problem for x86 as well, at least theoretically.
> >>>>>>>>>>>> xen_machine_power_off() may call pm_power_off(), which is efi.reset_system.
> >>>>>>>>>>>>
> >>>>>>>>>>>> So I think we should have a similar routine there.
> >>>>>>>>>>>
> >>>>>>>>>>> +1
> >>>>>>>>>>>
> >>>>>>>>>>> I don't see any problem with such a routine added, in contrast to
> >>>>>>>>>>> potential "reboots" instead of power off without it.
> >>>>>>>>>>>
> >>>>>>>>>>> So I think this dummy xen_efi_reset_system() should be added to
> >>>>>>>>>>> drivers/xen/efi.c instead.
> >>>>>>>>>>
> >>>>>>>>>> I will resend the patch during day with xen_efi_reset_system moved
> >>>>>>>>>> to common code and implement the x86 counterpart (thought, I will
> >>>>>>>>>> not be able to test it).
> >>>>>>>>>
> >>>>>>>>> I think that this is ARM specific issue. On x86 machine_restart() calls
> >>>>>>>>> xen_restart(). Hence, everything works. So, I think that it should be
> >>>>>>>>> fixed only for ARM. Anyway, please CC me when you send a patch.
> >>>>>>>>
> >>>>>>>> What about xen_machine_power_off() (as stated in Boris' mail)?
> >>>>>>>
> >>>>>>> Guys what do you think about that:
> >>>>>>>
> >>>>>>> --- a/drivers/firmware/efi/reboot.c
> >>>>>>> +++ b/drivers/firmware/efi/reboot.c
> >>>>>>> @@ -55,7 +55,7 @@ static void efi_power_off(void)
> >>>>>>>
> >>>>>>> static int __init efi_shutdown_init(void)
> >>>>>>> {
> >>>>>>> -       if (!efi_enabled(EFI_RUNTIME_SERVICES))
> >>>>>>> +       if (!efi_enabled(EFI_RUNTIME_SERVICES) || efi_enabled(EFI_PARAVIRT))
> >>>>>>>                return -ENODEV;
> >>>>>>>
> >>>>>>>        if (efi_poweroff_required())
> >>>>>>>
> >>>>>>>
> >>>>>>> Julien, for ARM64 please take a look at arch/arm64/kernel/efi.c:efi_poweroff_required(void).
> >>>>>>>
> >>>>>>> I hope that tweaks for both files should solve our problem.
> >>>>>>
> >>>>>> This sounds good for power off (I haven't tried to power off DOM0
> >>>>>> yet). But this will not solve the restart problem (see
> >>>>>> machine_restart in arch/arm64/kernel/process.c) which call directly
> >>>>>> efi_reboot.
> >>>>>
> >>>>> Hmmm... It seems to me that efi.reset_system override with empty function
> >>>>> in arch/arm/xen/efi.c is the best solution. So, I see three patches here.
> >>>>> One for drivers/firmware/efi/reboot.c, one for arch/arm/xen/efi.c and one
> >>>>> for arch/arm64/kernel/efi.c. Does it make sense?
> >>>>
> >>>> I still think the empty function should be in drivers/xen/efi.c and we
> >>>> should use it in arch/x86/xen/efi.c, too.
> >>>
> >>> If you wish we can go that way too. Though I thing that we should fix
> >>> drivers/firmware/efi/reboot.c:efi_shutdown_init() too. Just in case.
> >>
> >> Sure, go ahead. I won't object.
> > 
> > For the Xen on ARM side, the original patch that started this thread
> > (20170405181417.15985-1-julien.grall@arm.com) is good to go, right?
> > 
> 
> As I said: the dummy xen_efi_reset_system() should be in
> drivers/xen/efi.c

OK. Who is working on it?

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#1625544

On 18/04/17 20:46, Stefano Stabellini wrote:
> On Tue, 18 Apr 2017, Juergen Gross wrote:
>> On 18/04/17 20:37, Stefano Stabellini wrote:
>>> On Thu, 6 Apr 2017, Juergen Gross wrote:
>>>> On 06/04/17 18:43, Daniel Kiper wrote:
>>>>> On Thu, Apr 06, 2017 at 06:22:44PM +0200, Juergen Gross wrote:
>>>>>> On 06/04/17 18:06, Daniel Kiper wrote:
>>>>>>> Hi Julien,
>>>>>>>
>>>>>>> On Thu, Apr 06, 2017 at 04:39:13PM +0100, Julien Grall wrote:
>>>>>>>> Hi Daniel,
>>>>>>>>
>>>>>>>> On 06/04/17 16:20, Daniel Kiper wrote:
>>>>>>>>> On Thu, Apr 06, 2017 at 04:38:24PM +0200, Juergen Gross wrote:
>>>>>>>>>> On 06/04/17 16:27, Daniel Kiper wrote:
>>>>>>>>>>> On Thu, Apr 06, 2017 at 09:32:32AM +0100, Julien Grall wrote:
>>>>>>>>>>>> Hi Juergen,
>>>>>>>>>>>>
>>>>>>>>>>>> On 06/04/17 07:23, Juergen Gross wrote:
>>>>>>>>>>>>> On 05/04/17 21:49, Boris Ostrovsky wrote:
>>>>>>>>>>>>>> On 04/05/2017 02:14 PM, Julien Grall wrote:
>>>>>>>>>>>>>>> The x86 code has theoritically a similar issue, altought EFI does not
>>>>>>>>>>>>>>> seem to be the preferred method. I have left it unimplemented on x86 and
>>>>>>>>>>>>>>> CCed Linux Xen x86 maintainers to know their view here.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> (+Daniel)
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> This could be a problem for x86 as well, at least theoretically.
>>>>>>>>>>>>>> xen_machine_power_off() may call pm_power_off(), which is efi.reset_system.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> So I think we should have a similar routine there.
>>>>>>>>>>>>>
>>>>>>>>>>>>> +1
>>>>>>>>>>>>>
>>>>>>>>>>>>> I don't see any problem with such a routine added, in contrast to
>>>>>>>>>>>>> potential "reboots" instead of power off without it.
>>>>>>>>>>>>>
>>>>>>>>>>>>> So I think this dummy xen_efi_reset_system() should be added to
>>>>>>>>>>>>> drivers/xen/efi.c instead.
>>>>>>>>>>>>
>>>>>>>>>>>> I will resend the patch during day with xen_efi_reset_system moved
>>>>>>>>>>>> to common code and implement the x86 counterpart (thought, I will
>>>>>>>>>>>> not be able to test it).
>>>>>>>>>>>
>>>>>>>>>>> I think that this is ARM specific issue. On x86 machine_restart() calls
>>>>>>>>>>> xen_restart(). Hence, everything works. So, I think that it should be
>>>>>>>>>>> fixed only for ARM. Anyway, please CC me when you send a patch.
>>>>>>>>>>
>>>>>>>>>> What about xen_machine_power_off() (as stated in Boris' mail)?
>>>>>>>>>
>>>>>>>>> Guys what do you think about that:
>>>>>>>>>
>>>>>>>>> --- a/drivers/firmware/efi/reboot.c
>>>>>>>>> +++ b/drivers/firmware/efi/reboot.c
>>>>>>>>> @@ -55,7 +55,7 @@ static void efi_power_off(void)
>>>>>>>>>
>>>>>>>>> static int __init efi_shutdown_init(void)
>>>>>>>>> {
>>>>>>>>> -       if (!efi_enabled(EFI_RUNTIME_SERVICES))
>>>>>>>>> +       if (!efi_enabled(EFI_RUNTIME_SERVICES) || efi_enabled(EFI_PARAVIRT))
>>>>>>>>>                return -ENODEV;
>>>>>>>>>
>>>>>>>>>        if (efi_poweroff_required())
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Julien, for ARM64 please take a look at arch/arm64/kernel/efi.c:efi_poweroff_required(void).
>>>>>>>>>
>>>>>>>>> I hope that tweaks for both files should solve our problem.
>>>>>>>>
>>>>>>>> This sounds good for power off (I haven't tried to power off DOM0
>>>>>>>> yet). But this will not solve the restart problem (see
>>>>>>>> machine_restart in arch/arm64/kernel/process.c) which call directly
>>>>>>>> efi_reboot.
>>>>>>>
>>>>>>> Hmmm... It seems to me that efi.reset_system override with empty function
>>>>>>> in arch/arm/xen/efi.c is the best solution. So, I see three patches here.
>>>>>>> One for drivers/firmware/efi/reboot.c, one for arch/arm/xen/efi.c and one
>>>>>>> for arch/arm64/kernel/efi.c. Does it make sense?
>>>>>>
>>>>>> I still think the empty function should be in drivers/xen/efi.c and we
>>>>>> should use it in arch/x86/xen/efi.c, too.
>>>>>
>>>>> If you wish we can go that way too. Though I thing that we should fix
>>>>> drivers/firmware/efi/reboot.c:efi_shutdown_init() too. Just in case.
>>>>
>>>> Sure, go ahead. I won't object.
>>>
>>> For the Xen on ARM side, the original patch that started this thread
>>> (20170405181417.15985-1-julien.grall@arm.com) is good to go, right?
>>>
>>
>> As I said: the dummy xen_efi_reset_system() should be in
>> drivers/xen/efi.c
> 
> OK. Who is working on it?

Didn't Julien say he would do it?


Juergen

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#1627726

Hi,

On 18/04/17 19:51, Juergen Gross wrote:
> On 18/04/17 20:46, Stefano Stabellini wrote:
>> On Tue, 18 Apr 2017, Juergen Gross wrote:
>>> On 18/04/17 20:37, Stefano Stabellini wrote:
>>>> On Thu, 6 Apr 2017, Juergen Gross wrote:
>>>>> On 06/04/17 18:43, Daniel Kiper wrote:
>>>>>> On Thu, Apr 06, 2017 at 06:22:44PM +0200, Juergen Gross wrote:
>>>>>>> On 06/04/17 18:06, Daniel Kiper wrote:
>>>>>>>> Hi Julien,
>>>>>>>>
>>>>>>>> On Thu, Apr 06, 2017 at 04:39:13PM +0100, Julien Grall wrote:
>>>>>>>>> Hi Daniel,
>>>>>>>>>
>>>>>>>>> On 06/04/17 16:20, Daniel Kiper wrote:
>>>>>>>>>> On Thu, Apr 06, 2017 at 04:38:24PM +0200, Juergen Gross wrote:
>>>>>>>>>>> On 06/04/17 16:27, Daniel Kiper wrote:
>>>>>>>>>>>> On Thu, Apr 06, 2017 at 09:32:32AM +0100, Julien Grall wrote:
>>>>>>>>>>>>> Hi Juergen,
>>>>>>>>>>>>>
>>>>>>>>>>>>> On 06/04/17 07:23, Juergen Gross wrote:
>>>>>>>>>>>>>> On 05/04/17 21:49, Boris Ostrovsky wrote:
>>>>>>>>>>>>>>> On 04/05/2017 02:14 PM, Julien Grall wrote:
>>>>>>>>>>>>>>>> The x86 code has theoritically a similar issue, altought EFI does not
>>>>>>>>>>>>>>>> seem to be the preferred method. I have left it unimplemented on x86 and
>>>>>>>>>>>>>>>> CCed Linux Xen x86 maintainers to know their view here.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> (+Daniel)
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> This could be a problem for x86 as well, at least theoretically.
>>>>>>>>>>>>>>> xen_machine_power_off() may call pm_power_off(), which is efi.reset_system.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> So I think we should have a similar routine there.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> +1
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I don't see any problem with such a routine added, in contrast to
>>>>>>>>>>>>>> potential "reboots" instead of power off without it.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> So I think this dummy xen_efi_reset_system() should be added to
>>>>>>>>>>>>>> drivers/xen/efi.c instead.
>>>>>>>>>>>>>
>>>>>>>>>>>>> I will resend the patch during day with xen_efi_reset_system moved
>>>>>>>>>>>>> to common code and implement the x86 counterpart (thought, I will
>>>>>>>>>>>>> not be able to test it).
>>>>>>>>>>>>
>>>>>>>>>>>> I think that this is ARM specific issue. On x86 machine_restart() calls
>>>>>>>>>>>> xen_restart(). Hence, everything works. So, I think that it should be
>>>>>>>>>>>> fixed only for ARM. Anyway, please CC me when you send a patch.
>>>>>>>>>>>
>>>>>>>>>>> What about xen_machine_power_off() (as stated in Boris' mail)?
>>>>>>>>>>
>>>>>>>>>> Guys what do you think about that:
>>>>>>>>>>
>>>>>>>>>> --- a/drivers/firmware/efi/reboot.c
>>>>>>>>>> +++ b/drivers/firmware/efi/reboot.c
>>>>>>>>>> @@ -55,7 +55,7 @@ static void efi_power_off(void)
>>>>>>>>>>
>>>>>>>>>> static int __init efi_shutdown_init(void)
>>>>>>>>>> {
>>>>>>>>>> -       if (!efi_enabled(EFI_RUNTIME_SERVICES))
>>>>>>>>>> +       if (!efi_enabled(EFI_RUNTIME_SERVICES) || efi_enabled(EFI_PARAVIRT))
>>>>>>>>>>                return -ENODEV;
>>>>>>>>>>
>>>>>>>>>>        if (efi_poweroff_required())
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Julien, for ARM64 please take a look at arch/arm64/kernel/efi.c:efi_poweroff_required(void).
>>>>>>>>>>
>>>>>>>>>> I hope that tweaks for both files should solve our problem.
>>>>>>>>>
>>>>>>>>> This sounds good for power off (I haven't tried to power off DOM0
>>>>>>>>> yet). But this will not solve the restart problem (see
>>>>>>>>> machine_restart in arch/arm64/kernel/process.c) which call directly
>>>>>>>>> efi_reboot.
>>>>>>>>
>>>>>>>> Hmmm... It seems to me that efi.reset_system override with empty function
>>>>>>>> in arch/arm/xen/efi.c is the best solution. So, I see three patches here.
>>>>>>>> One for drivers/firmware/efi/reboot.c, one for arch/arm/xen/efi.c and one
>>>>>>>> for arch/arm64/kernel/efi.c. Does it make sense?
>>>>>>>
>>>>>>> I still think the empty function should be in drivers/xen/efi.c and we
>>>>>>> should use it in arch/x86/xen/efi.c, too.
>>>>>>
>>>>>> If you wish we can go that way too. Though I thing that we should fix
>>>>>> drivers/firmware/efi/reboot.c:efi_shutdown_init() too. Just in case.
>>>>>
>>>>> Sure, go ahead. I won't object.
>>>>
>>>> For the Xen on ARM side, the original patch that started this thread
>>>> (20170405181417.15985-1-julien.grall@arm.com) is good to go, right?
>>>>
>>>
>>> As I said: the dummy xen_efi_reset_system() should be in
>>> drivers/xen/efi.c
>>
>> OK. Who is working on it?
>
> Didn't Julien say he would do it?

Yes. I looked at bit closer to the problem mention with power off. 
xen_efi_reset_system cannot be a NOP because there may not be fallback 
alternatives (see machine_power_off in arch/arm64/kernel/process.c)

So I think we would have to translate EFI_RESET* to Xen SHUTDOWN_* and 
then call HYPERVISOR_sched_op directly.

I will send a new version soon.

Cheers,

-- 
Julien Grall

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#1625540

On 18/04/17 20:37, Stefano Stabellini wrote:
> On Thu, 6 Apr 2017, Juergen Gross wrote:
>> On 06/04/17 18:43, Daniel Kiper wrote:
>>> On Thu, Apr 06, 2017 at 06:22:44PM +0200, Juergen Gross wrote:
>>>> On 06/04/17 18:06, Daniel Kiper wrote:
>>>>> Hi Julien,
>>>>>
>>>>> On Thu, Apr 06, 2017 at 04:39:13PM +0100, Julien Grall wrote:
>>>>>> Hi Daniel,
>>>>>>
>>>>>> On 06/04/17 16:20, Daniel Kiper wrote:
>>>>>>> On Thu, Apr 06, 2017 at 04:38:24PM +0200, Juergen Gross wrote:
>>>>>>>> On 06/04/17 16:27, Daniel Kiper wrote:
>>>>>>>>> On Thu, Apr 06, 2017 at 09:32:32AM +0100, Julien Grall wrote:
>>>>>>>>>> Hi Juergen,
>>>>>>>>>>
>>>>>>>>>> On 06/04/17 07:23, Juergen Gross wrote:
>>>>>>>>>>> On 05/04/17 21:49, Boris Ostrovsky wrote:
>>>>>>>>>>>> On 04/05/2017 02:14 PM, Julien Grall wrote:
>>>>>>>>>>>>> The x86 code has theoritically a similar issue, altought EFI does not
>>>>>>>>>>>>> seem to be the preferred method. I have left it unimplemented on x86 and
>>>>>>>>>>>>> CCed Linux Xen x86 maintainers to know their view here.
>>>>>>>>>>>>
>>>>>>>>>>>> (+Daniel)
>>>>>>>>>>>>
>>>>>>>>>>>> This could be a problem for x86 as well, at least theoretically.
>>>>>>>>>>>> xen_machine_power_off() may call pm_power_off(), which is efi.reset_system.
>>>>>>>>>>>>
>>>>>>>>>>>> So I think we should have a similar routine there.
>>>>>>>>>>>
>>>>>>>>>>> +1
>>>>>>>>>>>
>>>>>>>>>>> I don't see any problem with such a routine added, in contrast to
>>>>>>>>>>> potential "reboots" instead of power off without it.
>>>>>>>>>>>
>>>>>>>>>>> So I think this dummy xen_efi_reset_system() should be added to
>>>>>>>>>>> drivers/xen/efi.c instead.
>>>>>>>>>>
>>>>>>>>>> I will resend the patch during day with xen_efi_reset_system moved
>>>>>>>>>> to common code and implement the x86 counterpart (thought, I will
>>>>>>>>>> not be able to test it).
>>>>>>>>>
>>>>>>>>> I think that this is ARM specific issue. On x86 machine_restart() calls
>>>>>>>>> xen_restart(). Hence, everything works. So, I think that it should be
>>>>>>>>> fixed only for ARM. Anyway, please CC me when you send a patch.
>>>>>>>>
>>>>>>>> What about xen_machine_power_off() (as stated in Boris' mail)?
>>>>>>>
>>>>>>> Guys what do you think about that:
>>>>>>>
>>>>>>> --- a/drivers/firmware/efi/reboot.c
>>>>>>> +++ b/drivers/firmware/efi/reboot.c
>>>>>>> @@ -55,7 +55,7 @@ static void efi_power_off(void)
>>>>>>>
>>>>>>> static int __init efi_shutdown_init(void)
>>>>>>> {
>>>>>>> -       if (!efi_enabled(EFI_RUNTIME_SERVICES))
>>>>>>> +       if (!efi_enabled(EFI_RUNTIME_SERVICES) || efi_enabled(EFI_PARAVIRT))
>>>>>>>                return -ENODEV;
>>>>>>>
>>>>>>>        if (efi_poweroff_required())
>>>>>>>
>>>>>>>
>>>>>>> Julien, for ARM64 please take a look at arch/arm64/kernel/efi.c:efi_poweroff_required(void).
>>>>>>>
>>>>>>> I hope that tweaks for both files should solve our problem.
>>>>>>
>>>>>> This sounds good for power off (I haven't tried to power off DOM0
>>>>>> yet). But this will not solve the restart problem (see
>>>>>> machine_restart in arch/arm64/kernel/process.c) which call directly
>>>>>> efi_reboot.
>>>>>
>>>>> Hmmm... It seems to me that efi.reset_system override with empty function
>>>>> in arch/arm/xen/efi.c is the best solution. So, I see three patches here.
>>>>> One for drivers/firmware/efi/reboot.c, one for arch/arm/xen/efi.c and one
>>>>> for arch/arm64/kernel/efi.c. Does it make sense?
>>>>
>>>> I still think the empty function should be in drivers/xen/efi.c and we
>>>> should use it in arch/x86/xen/efi.c, too.
>>>
>>> If you wish we can go that way too. Though I thing that we should fix
>>> drivers/firmware/efi/reboot.c:efi_shutdown_init() too. Just in case.
>>
>> Sure, go ahead. I won't object.
> 
> For the Xen on ARM side, the original patch that started this thread
> (20170405181417.15985-1-julien.grall@arm.com) is good to go, right?
> 

As I said: the dummy xen_efi_reset_system() should be in
drivers/xen/efi.c


Juergen

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