From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1C29EC433EF for ; Thu, 5 May 2022 13:05:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378837AbiEENJ2 (ORCPT ); Thu, 5 May 2022 09:09:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378845AbiEENJZ (ORCPT ); Thu, 5 May 2022 09:09:25 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8BA5612A98; Thu, 5 May 2022 06:05:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=K5gn/7sp7L1lwAyBxMpQcFTyNqRFPph4Q66pGuhOfbY=; b=TwG/Y7SJWPlxMzvXvY6UbL6sJ+ CFdPhtngSc5X84rkj+dUERbEGZ73AHlrth6uXHT5iHF+Ye3jngcDInSWu4kT86DX2OSO8YnWqUqG4 pAQZ9NyHCOskp48HSEIXauRLverJszCC+n5H+8mWBhsdkvUOLKX9Llx6ExJu+0irM3/ShF79oYDx5 GWv6C1bWPCCo69R58DuhXQ+KO7UKApDx6uPydfhCGg/uVUE+Ka6kiRZJis5Y83J9M0MXPLPMXhBP7 byVsFvVwebplom62LBjJYn+vYrdl3OKyJ2sxoIOgI7viJrbJEbgpDUOLBnUqQgTTXKrcrWDWXP9a5 BHj9CxuQ==; Received: from [179.113.53.197] (helo=[192.168.1.60]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1nmbAj-0000uD-EM; Thu, 05 May 2022 15:05:33 +0200 Message-ID: <3bee47db-f771-b502-82a3-d6fac388aa89@igalia.com> Date: Thu, 5 May 2022 10:05:18 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: Should arm64 have a custom crash shutdown handler? Content-Language: en-US To: Mark Rutland , "Michael Kelley (LINUX)" Cc: Marc Zyngier , Catalin Marinas , will Deacon , Vitaly Kuznetsov , Russell King , Ard Biesheuvel , broonie@kernel.org, "linux-arm-kernel@lists.infradead.org" , linux-kernel , "linux-hyperv@vger.kernel.org" References: <427a8277-49f0-4317-d6c3-4a15d7070e55@igalia.com> <874k24igjf.wl-maz@kernel.org> <92645c41-96fd-2755-552f-133675721a24@igalia.com> From: "Guilherme G. Piccoli" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On 05/05/2022 09:53, Mark Rutland wrote: > [...] > Looking at those, the cleanup work is all arch-specific. What exactly would we > need to do on arm64, and why does it need to happen at that point specifically? > On arm64 we don't expect as much paravirtualization as on x86, so it's not > clear to me whether we need anything at all. > >> Anyway, the idea here was to gather a feedback on how "receptive" arm64 >> community would be to allow such customization, appreciated your feedback =) > > ... and are you trying to do this for Hyper-V or just using that as an example? > > I think we're not going to be very receptive without a more concrete example of > what you want. > > What exactly do *you* need, and *why*? Is that for Hyper-V or another hypervisor? > > Thanks > Mark. Hi Mark, my plan would be doing that for Hyper-V - kind of the same code, almost. For example, in hv_crash_handler() there is a stimer clean-up and the vmbus unload - my understanding is that this same code would need to run in arm64. Michael Kelley is CCed, he was discussing with me in the panic notifiers thread and may elaborate more on the needs. But also (not related with my specific plan), I've seen KVM quiesce code on x86 as well [see kvm_crash_shutdown() on arch/x86] , I'm not sure if this is necessary for arm64 or if this already executing in some abstracted form, I didn't dig deep - probably Vitaly is aware of that, hence I've CCed him here. Cheers, Guilherme