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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=ham 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 87497C4361B for ; Thu, 10 Dec 2020 14:13:44 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 88C5722BF5 for ; Thu, 10 Dec 2020 14:13:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 88C5722BF5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kaod.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38960 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1knMhS-0003H1-Js for qemu-devel@archiver.kernel.org; Thu, 10 Dec 2020 09:13:42 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:55386) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1knMVj-0008Pi-Oc for qemu-devel@nongnu.org; Thu, 10 Dec 2020 09:01:35 -0500 Received: from 4.mo52.mail-out.ovh.net ([178.33.43.201]:45314) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1knMVZ-000729-QV for qemu-devel@nongnu.org; Thu, 10 Dec 2020 09:01:35 -0500 Received: from mxplan5.mail.ovh.net (unknown [10.109.156.216]) by mo52.mail-out.ovh.net (Postfix) with ESMTPS id 23EA0221B74; Thu, 10 Dec 2020 15:01:22 +0100 (CET) Received: from kaod.org (37.59.142.104) by DAG8EX1.mxp5.local (172.16.2.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2044.4; Thu, 10 Dec 2020 15:01:21 +0100 Authentication-Results: garm.ovh; auth=pass (GARM-104R0053590302a-f4f5-44a1-81ed-c09b9b4470b7, 7F90A86A4359BCD1ACB0618936AE64BD6AD86209) smtp.auth=groug@kaod.org Date: Thu, 10 Dec 2020 15:01:20 +0100 From: Greg Kurz To: Daniel Henrique Barboza Subject: Re: [PATCH v2 1/1] spapr.c: set a 'kvm-type' default value instead of relying on NULL Message-ID: <20201210150120.128ab5a2@bahia.lan> In-Reply-To: <20201210130721.1521487-2-danielhb413@gmail.com> References: <20201210130721.1521487-1-danielhb413@gmail.com> <20201210130721.1521487-2-danielhb413@gmail.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [37.59.142.104] X-ClientProxiedBy: DAG1EX2.mxp5.local (172.16.2.2) To DAG8EX1.mxp5.local (172.16.2.71) X-Ovh-Tracer-GUID: e35db272-6159-40f4-9fea-b5816b071d94 X-Ovh-Tracer-Id: 3040211223922252195 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedujedrudektddgheelucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuqfggjfdpvefjgfevmfevgfenuceurghilhhouhhtmecuhedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhepfffhvffukfgjfhfogggtgfhisehtjeertdertddvnecuhfhrohhmpefirhgvghcumfhurhiiuceoghhrohhugheskhgrohgurdhorhhgqeenucggtffrrghtthgvrhhnpeefuddtieejjeevheekieeltefgleetkeetheettdeifeffvefhffelffdtfeeljeenucfkpheptddrtddrtddrtddpfeejrdehledrudegvddruddtgeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhhouggvpehsmhhtphdqohhuthdphhgvlhhopehmgihplhgrnhehrdhmrghilhdrohhvhhdrnhgvthdpihhnvghtpedtrddtrddtrddtpdhmrghilhhfrhhomhepghhrohhugheskhgrohgurdhorhhgpdhrtghpthhtohepphgsohhniihinhhisehrvgguhhgrthdrtghomh Received-SPF: pass client-ip=178.33.43.201; envelope-from=groug@kaod.org; helo=4.mo52.mail-out.ovh.net X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pbonzini@redhat.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org, david@gibson.dropbear.id.au Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 10 Dec 2020 10:07:21 -0300 Daniel Henrique Barboza wrote: > spapr_kvm_type() is considering 'vm_type=NULL' as a valid input, where > the function returns 0. This is relying on the current QEMU machine > options handling logic, where the absence of the 'kvm-type' option > will be reflected as 'vm_type=NULL' in this function. > > This is not robust, and will break if QEMU options code decides to propagate > something else in the case mentioned above (e.g. an empty string instead > of NULL). > > Let's avoid this entirely by setting a non-NULL default value in case of > no user input for 'kvm-type'. spapr_kvm_type() was changed to handle 3 fixed > values of kvm-type: "auto", "hv", and "pr", with "auto" being the default > if no kvm-type was set by the user. This allows us to always be predictable > regardless of any enhancements/changes made in QEMU options mechanics. > > While we're at it, let's also document in 'kvm-type' description the > already existing default mode, now named 'auto'. The information provided > about it is based on how the pseries kernel handles the KVM_CREATE_VM > ioctl(), where the default value '0' makes the kernel choose an available > KVM module to use, giving precedence to kvm_hv. This logic is described in > the kernel source file arch/powerpc/kvm/powerpc.c, function kvm_arch_init_vm(). > > Signed-off-by: Daniel Henrique Barboza > --- > hw/ppc/spapr.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c > index b7e0894019..f097f4ea30 100644 > --- a/hw/ppc/spapr.c > +++ b/hw/ppc/spapr.c > @@ -3021,17 +3021,18 @@ static void spapr_machine_init(MachineState *machine) > qemu_cond_init(&spapr->fwnmi_machine_check_interlock_cond); > } > > +#define DEFAULT_KVM_TYPE "auto" > static int spapr_kvm_type(MachineState *machine, const char *vm_type) > { > - if (!vm_type) { > + if (!g_ascii_strcasecmp(vm_type, DEFAULT_KVM_TYPE)) { strcmp() would be better here : we don't want to support an already existing "AUTO" value like for the other ones. And, of course, add a comment to explain why the two other ones are handled differently. > return 0; > } > > - if (!strcmp(vm_type, "HV")) { > + if (!g_ascii_strcasecmp(vm_type, "hv")) { > return 1; > } > > - if (!strcmp(vm_type, "PR")) { > + if (!g_ascii_strcasecmp(vm_type, "pr")) { > return 2; > } > > @@ -3131,7 +3132,7 @@ static char *spapr_get_kvm_type(Object *obj, Error **errp) > { > SpaprMachineState *spapr = SPAPR_MACHINE(obj); > > - return g_strdup(spapr->kvm_type); > + return g_strdup(spapr->kvm_type ? spapr->kvm_type : DEFAULT_KVM_TYPE); As in Paolo's diff, it seems better to simply initialize spapr->kvm_type ... > } > > static void spapr_set_kvm_type(Object *obj, const char *value, Error **errp) > @@ -3273,7 +3274,11 @@ static void spapr_instance_init(Object *obj) ... here. spapr->kvm_type = g_strdup(DEFAULT_KVM_TYPE); > object_property_add_str(obj, "kvm-type", > spapr_get_kvm_type, spapr_set_kvm_type); > object_property_set_description(obj, "kvm-type", > - "Specifies the KVM virtualization mode (HV, PR)"); > + "Specifies the KVM virtualization mode (auto," > + " hv, pr). Defaults to 'auto'. This mode will use" > + " any available KVM module loaded in the host," > + " where kvm_hv takes precedence if both kvm_hv and" > + " kvm_pr are loaded."); > object_property_add_bool(obj, "modern-hotplug-events", > spapr_get_modern_hotplug_events, > spapr_set_modern_hotplug_events);