From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH 2/2] ARM: soft-reboot into same mode that we entered the kernel Date: Wed, 14 Dec 2016 12:29:45 +0000 Message-ID: <20161214122945.GE14217@n2100.armlinux.org.uk> References: <20161213113044.GC19985@leverpostej> <20161214115648.GG17982@leverpostej> <20161214120541.GD14217@n2100.armlinux.org.uk> <20161214121747.GH17982@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D43E84022C for ; Wed, 14 Dec 2016 07:28:51 -0500 (EST) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 3VVrajFUjaYT for ; Wed, 14 Dec 2016 07:28:50 -0500 (EST) Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 7935240354 for ; Wed, 14 Dec 2016 07:28:50 -0500 (EST) Content-Disposition: inline In-Reply-To: <20161214121747.GH17982@leverpostej> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: Mark Rutland Cc: marc.zyngier@arm.com, linux-arm-kernel@lists.infradead.org, dave.martin@arm.com, kvmarm@lists.cs.columbia.edu List-Id: kvmarm@lists.cs.columbia.edu On Wed, Dec 14, 2016 at 12:17:47PM +0000, Mark Rutland wrote: > On Wed, Dec 14, 2016 at 12:05:41PM +0000, Russell King - ARM Linux wrote: > > The issue here is that a panic can happen at any time from any context > > with any hyp stub in place, so there _needs_ to be a uniform way to do > > this. It's very bad that we've got this far without this point having > > been considered - all we can do right now is to try and fix the issues > > as they come up. > > > > Right now, let's fix this so we get some kind of improvement, and later > > try to sort out some kind of uniform interface for this task. > > Sure, that's a bigger task, and this is definitely a step in the right > direction. > > We need to avoid the kdump regression somehow though; can we somehow > detect if KVM is active and avoid issuing the HVC_SOFT_RESTART? That's a question for KVM people. However, there's a bigger question, which is: what do we want to happen in the case of kdump - do we want to be entering the kdump kernel in HYP or SVC mode? As the kdump kernel exists to be able to save the state of a crashing system, the kdump kernel should do that and then restart the system in a clean way (iow, not via yet another kexec.) So maybe the right answer is that kdump should always invoke the kernel in SVC mode. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.