From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v4 00/21] SError rework + RAS&IESB for firmware first support Date: Tue, 31 Oct 2017 10:08:29 +0000 Message-ID: <20171031100829.GC5584@arm.com> References: <20171019145807.23251-1-james.morse@arm.com> <20171031063535.GA2166@lvm> 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 0F34C49D09 for ; Tue, 31 Oct 2017 06:07:00 -0400 (EDT) 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 IPn-RdhrIEGs for ; Tue, 31 Oct 2017 06:06:53 -0400 (EDT) Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id CEC8440795 for ; Tue, 31 Oct 2017 06:06:53 -0400 (EDT) Content-Disposition: inline In-Reply-To: <20171031063535.GA2166@lvm> 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: Christoffer Dall Cc: Jonathan.Zhang@cavium.com, Marc Zyngier , Catalin Marinas , Julien Thierry , wangxiongfeng2@huawei.com, linux-arm-kernel@lists.infradead.org, Dongjiu Geng , kvmarm@lists.cs.columbia.edu List-Id: kvmarm@lists.cs.columbia.edu On Tue, Oct 31, 2017 at 07:35:35AM +0100, Christoffer Dall wrote: > Hi James, Catalin, and Will, > > On Thu, Oct 19, 2017 at 03:57:46PM +0100, James Morse wrote: > > Hello, > > > > The aim of this series is to enable IESB and add ESB-instructions to let us > > kick any pending RAS errors into firmware to be handled by firmware-first. > > > > Not all systems will have this firmware, so these RAS errors will become > > pending SErrors. We should take these as quickly as possible and avoid > > panic()ing for errors where we could have continued. > > > > This first part of this series reworks the DAIF masking so that SError is > > unmasked unless we are handling a debug exception. > > > > The last part provides the same minimal handling for SError that interrupt > > KVM. KVM is currently unable to handle SErrors during world-switch, unless > > they occur during a magic single-instruction window, it hyp-panics. I suspect > > this will be easier to fix once the VHE world-switch is further optimised. > > > > KVMs kvm_inject_vabt() needs updating for v8.2 as now we can specify an ESR, > > and all-zeros has a RAS meaning. > > > > KVM's existing 'impdef SError to the guest' behaviour probably needs revisiting. > > These are errors where we don't know what they mean, they may not be > > synchronised by ESB. Today we blame the guest. > > My half-baked suggestion would be to make a virtual SError pending, but then > > exit to user-space to give Qemu the change to quit (for virtual machines that > > don't generate SError), pend an SError with a new Qemu-specific ESR, or blindly > > continue and take KVMs default all-zeros impdef ESR. > > The KVM side of this series is looking pretty good. > > What are the merge plans for this? I am fine if you will take this via > the arm64 tree with our acks from the KVM side. Alternatively, I > suppose you can apply all the arm64 patches and provide us with a stable > branch for that? I'll take a look this afternoon, but we haven't had a linux next release since the 18th so I'm starting to get nervous about conflicts if I end up pulling in new trees now. Will