Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755559AbdDRSvm (ORCPT ); Tue, 18 Apr 2017 14:51:42 -0400 Received: from mx2.suse.de ([195.135.220.15]:54988 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753408AbdDRSvj (ORCPT ); Tue, 18 Apr 2017 14:51:39 -0400 Subject: Re: [PATCH] arm64: xen: Implement EFI reset_system callback To: Stefano Stabellini 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: Daniel Kiper , Julien Grall , Boris Ostrovsky , xen-devel@lists.xen.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org From: Juergen Gross Message-ID: Date: Tue, 18 Apr 2017 20:51:36 +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: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4285 Lines: 100 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