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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4EBF2C433F5 for ; Tue, 24 May 2022 12:27:53 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4L6tkv4nD1z3c7F for ; Tue, 24 May 2022 22:27:51 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=suse.com header.i=@suse.com header.a=rsa-sha256 header.s=susede1 header.b=cmANZ9ka; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=suse.com (client-ip=195.135.220.29; helo=smtp-out2.suse.de; envelope-from=pmladek@suse.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=suse.com header.i=@suse.com header.a=rsa-sha256 header.s=susede1 header.b=cmANZ9ka; dkim-atps=neutral Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4L6mvW2kXlz2yLg for ; Tue, 24 May 2022 18:04:55 +1000 (AEST) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id C6A001F8B8; Tue, 24 May 2022 08:04:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1653379492; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+HrTVIvXJDgrzNQFl8Mhx0wGW/HWHO1IHY/NT0Ch0wc=; b=cmANZ9kaIvAGzRMHaeCxB0LLBkrlXozlKGlr2MQNHSGuBkVg9GZ4ULppK80AYEMbn3sHQ3 SRCkpAxtJlotC4dIBTUf4LWabWRfn+CV2iXTLVzyyBDKp8B9onijAa8QBBUxy4R2DAxIkT C3aqZP5pWFL7HdTOLlEm50sKDepVyxc= Received: from suse.cz (unknown [10.100.201.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id A47272C141; Tue, 24 May 2022 08:04:51 +0000 (UTC) Date: Tue, 24 May 2022 10:04:51 +0200 From: Petr Mladek To: "Guilherme G. Piccoli" Subject: Re: [PATCH 19/30] panic: Add the panic hypervisor notifier list Message-ID: References: <20220427224924.592546-1-gpiccoli@igalia.com> <20220427224924.592546-20-gpiccoli@igalia.com> <81878a67-21f1-fee8-1add-f381bc8b05df@broadcom.com> <0fac8c71-6f18-d15c-23f5-075dbc45f3f9@igalia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0fac8c71-6f18-d15c-23f5-075dbc45f3f9@igalia.com> X-Mailman-Approved-At: Tue, 24 May 2022 22:27:19 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paul Mackerras , Justin Chen , Pavel Machek , Alexander Gordeev , "K. Y. Srinivasan" , Wei Liu , stern@rowland.harvard.edu, xen-devel@lists.xenproject.org, Christian Borntraeger , linux-pm@vger.kernel.org, linux-um@lists.infradead.org, Nicholas Piggin , luto@kernel.org, Mihai Carabas , tglx@linutronix.de, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, senozhatsky@chromium.org, d.hatayama@jp.fujitsu.com, mhiramat@kernel.org, akpm@linux-foundation.org, linux-hyperv@vger.kernel.org, dave.hansen@linux.intel.com, linux-s390@vger.kernel.org, Stephen Hemminger , Vasily Gorbik , vgoyal@redhat.com, Sven Schnelle , Andrea Parri , linux-xtensa@linux-xtensa.org, john.ogness@linutronix.de, Scott Branden , Doug Berger , Markus Mayer , hidehiro.kawai.ez@hitachi.com, linux-arm-kernel@lists.infradead.org, kernel-dev@igalia.com, fabiomirmar@gmail.com, halves@canonical.com, alejandro.j.jimenez@oracle.com, feng.tang@intel.com, zhenwei pi , will@kernel.org, Florian Fainelli , bhe@redhat.com, corbet@lwn.net, Dexuan Cui , Evan Green , bcm-kernel-feedback-list@broadcom.com, Tianyu Lan , keescook@chromium.org, arnd@arndb.de, Haiyang Zhang , rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, openipmi-developer@lists.sourceforge.net, Thomas Bogendoerfer , linux-parisc@vger.kernel.org, Sebastian Reichel , linux-alpha@vger.kernel.org, Brian Norris , "David S. Miller" , peterz@infradead.org, linux-remoteproc@vger.kernel.org, mikelley@microsoft.com, sparclinux@vger.kernel.org, Lee Jones , Ard Biesheuvel , linux-leds@vger.kernel.org, x86@kernel.org, mingo@redhat.com, Desmond yan , dyoung@redhat.com, paulmck@kernel.org, Heiko Carstens , Shile Zhang , Wang ShaoBo , Christophe JAILLET , David Gow , linux-tegra@vger.kernel.org, andriy.shevchenko@linux.intel.com, Hari Bathini , linux-edac@vger.kernel.org, jgross@suse.com, netdev@vger.kernel.org, kernel@gpiccoli.net, kexec@lists.infradead.org, linux-mips@vger.kernel.org, Julius Werner , vkuznets@redhat.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon 2022-05-23 11:56:12, Guilherme G. Piccoli wrote: > On 19/05/2022 16:20, Scott Branden wrote: > > [...] > >> Hi Scott / Desmond, thanks for the detailed answer! Is this adapter > >> designed to run in x86 only or you have other architectures' use cases? > > The adapter may be used in any PCIe design that supports DMA. > > So it may be possible to run in arm64 servers. > >> > >> [...] > >> With that said, and given this is a lightweight notifier that ideally > >> should run ASAP, I'd keep this one in the hypervisor list. We can > >> "adjust" the semantic of this list to include lightweight notifiers that > >> reset adapters. > > Sounds the best to keep system operating as tested today. > >> > >> With that said, Petr has a point - not always such list is going to be > >> called before kdump. So, that makes me think in another idea: what if we > >> have another list, but not on panic path, but instead in the custom > >> crash_shutdown()? Drivers could add callbacks there that must execute > >> before kexec/kdump, no matter what. > > It may be beneficial for some other drivers but for our use we would > > then need to register for the panic path and the crash_shutdown path. > > We notify the VK card for 2 purposes: one to stop DMA so memory stop > > changing during a kdump. And also to get the card into a good state so > > resets happen cleanly. > > Thanks Scott! With that, I guess it's really better to keep this > notifier in this hypervisor/early list - I'm planning to do that for V2. > Unless Petr or somebody has strong feelings against that, of course. I am fine with it because we do not have a better solution at the moment. It might be a good candidate for the 5th notifier list mentioned in the thread https://lore.kernel.org/r/YoyQyHHfhIIXSX0U@alley . But I am not sure if the 5th list is worth the complexity. Best Regards, Petr