Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754470AbdDRShI (ORCPT ); Tue, 18 Apr 2017 14:37:08 -0400 Received: from mail.kernel.org ([198.145.29.136]:33522 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752179AbdDRShF (ORCPT ); Tue, 18 Apr 2017 14:37:05 -0400 Date: Tue, 18 Apr 2017 11:37:01 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-X260 To: Juergen Gross cc: Daniel Kiper , Julien Grall , Boris Ostrovsky , xen-devel@lists.xen.org, sstabellini@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64: xen: Implement EFI reset_system callback In-Reply-To: Message-ID: References: <20170405181417.15985-1-julien.grall@arm.com> <3f6f5853-cd08-8afc-f71a-b0c1545c7564@arm.com> <20170406142710.GE4372@olila.local.net-space.pl> <20170406152040.GH4372@olila.local.net-space.pl> <20170406160653.GJ4372@olila.local.net-space.pl> <20170406164309.GM4372@olila.local.net-space.pl> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3804 Lines: 86 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?