From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Guilherme G. Piccoli" Subject: Re: [PATCH 19/30] panic: Add the panic hypervisor notifier list Date: Mon, 23 May 2022 11:56:12 -0300 Message-ID: <0fac8c71-6f18-d15c-23f5-075dbc45f3f9@igalia.com> References: <20220427224924.592546-1-gpiccoli@igalia.com> <20220427224924.592546-20-gpiccoli@igalia.com> <81878a67-21f1-fee8-1add-f381bc8b05df@broadcom.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: 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=keKJrvyQ/+r75XOnYYRl19FO+VGyiPJcwICfZxDBkqs=; b=O+C3jDB0Vwu4Y/gkTmW/RCmTwy kNqD2emzzlOs/8A7J1xO/TSH5qapt6sCckUwfqeKLJwoCrpUi4pUQfOKCsbI70QtSFMdfNTmFr+H0 NXT6Oh9iPuG4hVKz84ZvxHpmEirVLNSMQMza54o3VmB+D23FpdTtf7JnpYZ61zk10z8NLp053Dtmb 5G5TvLT8W+VF+imYpIQccZx+LAQHhkmqjWgwAULVFomENEWSpKhN5UeAVPt+Y1vZC04/4FyRoMtUE OHqcld4S4ftUjXzRb6CJS95k+7T+FIlHKMRNj13Qcs75Xk/j3Ix2WaTpEwsP72+2bzr+hEFsSu6v0 WUJ5ifA Content-Language: en-US In-Reply-To: List-ID: Content-Type: text/plain; charset="us-ascii" To: Scott Branden , Petr Mladek , Sebastian Reichel , Florian Fainelli , Desmond yan Cc: David Gow , Evan Green , Julius Werner , bcm-kernel-feedback-list-dY08KVG/lbpWk0Htik3J/w@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-alpha-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-edac-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-hyperv-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-leds-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mips-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-parisc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-remoteproc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-um-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-xtensa-PjhNF2WwrV/0Sa2dR60CXw@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, openipmi-developer-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, rcu-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sparclinux-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, xen-devel@li 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. Cheers, Guilherme