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 X-Spam-Level: X-Spam-Status: No, score=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88553C433E0 for ; Tue, 4 Aug 2020 17:16:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 70A84207FC for ; Tue, 4 Aug 2020 17:16:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596561396; bh=KgUSQXHnQmyfVqBx7P8DiLDgLrGMLQ5sEeXPjkKaMgo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=NgsmoPqrJCbZKm8RgycSQv67ZB8Fvm3V0dMYGaZ+l1Zw1VoZHGTz9g/Q82njNPGvr VFbP32wWQ8nkTUl9rCg8OobRkdo6hiHgPNQHg/FjbAoU3U4vYBmLwscK+Z4M17fKWd c0CCqlJZ8dDaUlkO6glVoBNqD0wDdZ7x3HmoRnFc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729978AbgHDRQe (ORCPT ); Tue, 4 Aug 2020 13:16:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:33078 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729760AbgHDRQc (ORCPT ); Tue, 4 Aug 2020 13:16:32 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 00B8F207FC; Tue, 4 Aug 2020 17:16:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596561392; bh=KgUSQXHnQmyfVqBx7P8DiLDgLrGMLQ5sEeXPjkKaMgo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=po6Awiu2jyPPa8K7P1obOSX43I7xN26lmV3hDkANXkQYWOVML8pKHGk7i8bZvGsXJ C7YOUuBeHSAf5ybIvPArid5p2sVn2opD172H2vkd7LXJ3RBWN+wElJAYGQ02xwutbi T1rDroNvCn5e/s/uutC20fI/FKFmzW8QVPCvkUro= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1k30YA-00HReQ-IA; Tue, 04 Aug 2020 18:16:30 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Tue, 04 Aug 2020 18:16:30 +0100 From: Marc Zyngier To: =?UTF-8?Q?Alex_Benn=C3=A9e?= Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu, christoffer.dall@arm.com Subject: Re: [PATCH v1 3/3] kernel/configs: don't include PCI_QUIRKS in KVM guest configs In-Reply-To: <87lfiumnc8.fsf@linaro.org> References: <20200804124417.27102-1-alex.bennee@linaro.org> <20200804124417.27102-4-alex.bennee@linaro.org> <87r1smmpw5.fsf@linaro.org> <87lfiumnc8.fsf@linaro.org> User-Agent: Roundcube Webmail/1.4.5 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: alex.bennee@linaro.org, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu, christoffer.dall@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-08-04 16:40, Alex Bennée wrote: > Marc Zyngier writes: > >> On 2020-08-04 15:44, Alex Bennée wrote: >>> Marc Zyngier writes: >>> >>>> On 2020-08-04 13:44, Alex Bennée wrote: >>>>> The VIRTIO_PCI support is an idealised PCI bus, we don't need a >>>>> bunch >>>>> of bloat for real world hardware for a VirtIO guest. >>>> >>>> Who says this guest will only have virtio devices? >>> >>> This is true - although what is the point of kvm_guest.config? We >>> certainly turn on a whole bunch of virt optimised pathways with >>> PARAVIRT >>> and HYPERVISOR_GUEST along with the rest of VirtIO. >> >> Most of which actually qualifies as bloat itself as far as KVM/arm64 >> is concerned... > > So here is the question - does the kernel care about having a blessed > config for a minimal viable guest? They are certainly used in the cloud > but I understand the kernel is trying to get away from having a zoo of > configs. What is the actual point of kvm_guest.config? Just an easy > enabling for developers? The cloud vendor I know certainly doesn't provide a "dumbed down" kernel configuration. What they run is either a distro kernel or something that fits their environment (which does include HW PCI devices, and hardly any virtio device). My take is that this kvm-special config isn't that useful in the real world, and I don't believe there is such thing as a "minimal viable guest" config, certainly not across architectures and VMMs. Hopefully it fits someone's development workflow, but that's probably it. M. -- Jazz is not dead. It just smells funny...