Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755539AbdDFRjs (ORCPT ); Thu, 6 Apr 2017 13:39:48 -0400 Received: from mx2.suse.de ([195.135.220.15]:43336 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752410AbdDFRjW (ORCPT ); Thu, 6 Apr 2017 13:39:22 -0400 Subject: Re: [PATCH] arm64: xen: Implement EFI reset_system callback To: Daniel Kiper 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> Cc: Julien Grall , Boris Ostrovsky , xen-devel@lists.xen.org, sstabellini@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org From: Juergen Gross Message-ID: Date: Thu, 6 Apr 2017 19:39:18 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170406164309.GM4372@olila.local.net-space.pl> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3471 Lines: 85 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. Juergen