From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161260AbbKFL7f (ORCPT ); Fri, 6 Nov 2015 06:59:35 -0500 Received: from foss.arm.com ([217.140.101.70]:41455 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1032739AbbKFL7e (ORCPT ); Fri, 6 Nov 2015 06:59:34 -0500 Date: Fri, 6 Nov 2015 11:59:16 +0000 From: Mark Rutland To: David Vrabel Cc: Stefano Stabellini , xen-devel@lists.xensource.com, linux@arm.linux.org.uk, Ian Campbell , arnd@arndb.de, marc.zyngier@arm.com, catalin.marinas@arm.com, konrad.wilk@oracle.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, olof@lixom.net, linux-arm-kernel@lists.infradead.org, vkuznets@redhat.com, geoff@infradead.org, takahiro.akashi@linaro.org Subject: Re: [PATCH v11 5/5] xen/arm: account for stolen ticks Message-ID: <20151106115916.GA23038@leverpostej> References: <1446737696-9749-5-git-send-email-stefano.stabellini@eu.citrix.com> <20151105165743.GG32247@leverpostej> <563C91FD.7060703@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <563C91FD.7060703@citrix.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 06, 2015 at 11:41:49AM +0000, David Vrabel wrote: > On 06/11/15 11:39, Stefano Stabellini wrote: > > On Thu, 5 Nov 2015, Mark Rutland wrote: > >>> static void xen_percpu_init(void) > >>> { > >>> struct vcpu_register_vcpu_info info; > >>> @@ -104,6 +120,8 @@ static void xen_percpu_init(void) > >>> BUG_ON(err); > >>> per_cpu(xen_vcpu, cpu) = vcpup; > >>> > >>> + xen_setup_runstate_info(cpu); > >> > >> Does the runstate memory area get unregsitered when a kernel tears > >> things down, or is kexec somehow inhibited for xen guests? > >> > >> i couldn't spot either happening, but I may have missed it. > > > > I don't think that the runstate memory area needs to be unregistered for > > kexec, but I am not very knowledgeble on kexec and Xen, CC'ing Vitaly > > and David. > > There's a whole pile of other state needing to be reset for kexec (event > channels and grant tables for example). The guest needs to soft reset > itself (available in Xen 4.6) before kexec'ing another kernel. > > This soft reset would also including cleaning up this shared memory region. Ok. So we don't currently have the code kernel-side, but it looks like it would be relatively simple to add (having just spotted [1]), and everything should be ready on the Xen side.` Thanks, Mark. [1] https://lkml.org/lkml/2015/9/25/152