Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935272AbdDFOh4 (ORCPT ); Thu, 6 Apr 2017 10:37:56 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:46523 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755595AbdDFOht (ORCPT ); Thu, 6 Apr 2017 10:37:49 -0400 Subject: Re: [PATCH] arm64: xen: Implement EFI reset_system callback To: Julien Grall , Daniel Kiper References: <20170405181417.15985-1-julien.grall@arm.com> <3f6f5853-cd08-8afc-f71a-b0c1545c7564@arm.com> <20170406142710.GE4372@olila.local.net-space.pl> <557da0c0-233b-1f56-242e-e8bc90892827@arm.com> Cc: Juergen Gross , xen-devel@lists.xen.org, sstabellini@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org From: Boris Ostrovsky Message-ID: <90916004-b553-927b-fc8e-2758f8ba04a3@oracle.com> Date: Thu, 6 Apr 2017 10:37:11 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: <557da0c0-233b-1f56-242e-e8bc90892827@arm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1699 Lines: 48 On 04/06/2017 10:32 AM, Julien Grall wrote: > Hi Daniel, > > On 06/04/17 15:27, 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. > > This thread already a fix for ARM64. So do I need to resend a patch > with x86 fixed or not? Yes please. Daniel is correct that we are safe with xen_restart(). However, we are not safe when machine_ops.power_off is called. Thanks. -boris