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.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 smtp.lore.kernel.org (Postfix) with ESMTPS id 31D04C433EF for ; Fri, 11 Mar 2022 10:12:21 +0000 (UTC) Received: from localhost ([::1]:41440 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nScFw-0004OE-3s for qemu-devel@archiver.kernel.org; Fri, 11 Mar 2022 05:12:20 -0500 Received: from eggs.gnu.org ([209.51.188.92]:45958) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nScDo-0001xH-UG for qemu-devel@nongnu.org; Fri, 11 Mar 2022 05:10:14 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:54213) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nScDm-0003Sl-8P for qemu-devel@nongnu.org; Fri, 11 Mar 2022 05:10:08 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1646993405; h=from:from:reply-to:reply-to:subject:subject: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=P5tMpq8QgggNPj8vr96zMSOAMAai2QDI7lYHO+90L/I=; b=Z6nv80fy4b0vcr5sKqkKlCaCjVFLVUbWD0hQN0k36/w6oPzoD0HGOpj9JBVvC2t/AdFjxx OAcBNKVcdhDjgGUxB3n4gHfr3YwX65sgQnKFIUMNydjlJfTBs0oVPkuNnzqWZn94tS2//v dnP8Rjzq8udvWatWyEbnnyvTEMMWmvg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-152-tdyB9PK_NFmu7swN6P7Ydg-1; Fri, 11 Mar 2022 05:09:58 -0500 X-MC-Unique: tdyB9PK_NFmu7swN6P7Ydg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EE7211006AA6; Fri, 11 Mar 2022 10:09:56 +0000 (UTC) Received: from redhat.com (unknown [10.39.193.251]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 858BA7A5CE; Fri, 11 Mar 2022 10:09:00 +0000 (UTC) Date: Fri, 11 Mar 2022 10:08:57 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Steven Sistare Subject: Re: [PATCH V7 10/29] machine: memfd-alloc option Message-ID: References: <1640199934-455149-1-git-send-email-steven.sistare@oracle.com> <1640199934-455149-11-git-send-email-steven.sistare@oracle.com> <20220303121534-mutt-send-email-mst@kernel.org> <20220304114124.6fe97646@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.1.5 (2021-12-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Jason Zeng , Juan Quintela , Eric Blake , "Michael S. Tsirkin" , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" , Zheng Chuan , Alex Williamson , Paolo Bonzini , Stefan Hajnoczi , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Igor Mammedov , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Alex =?utf-8?Q?Benn=C3=A9e?= , Markus Armbruster Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Mar 07, 2022 at 09:41:44AM -0500, Steven Sistare wrote: > On 3/4/2022 5:41 AM, Igor Mammedov wrote: > > On Thu, 3 Mar 2022 12:21:15 -0500 > > "Michael S. Tsirkin" wrote: > > > >> On Wed, Dec 22, 2021 at 11:05:15AM -0800, Steve Sistare wrote: > >>> Allocate anonymous memory using memfd_create if the memfd-alloc machine > >>> option is set. > >>> > >>> Signed-off-by: Steve Sistare > >>> --- > >>> hw/core/machine.c | 19 +++++++++++++++++++ > >>> include/hw/boards.h | 1 + > >>> qemu-options.hx | 6 ++++++ > >>> softmmu/physmem.c | 47 ++++++++++++++++++++++++++++++++++++++--------- > >>> softmmu/vl.c | 1 + > >>> trace-events | 1 + > >>> util/qemu-config.c | 4 ++++ > >>> 7 files changed, 70 insertions(+), 9 deletions(-) > >>> > >>> diff --git a/hw/core/machine.c b/hw/core/machine.c > >>> index 53a99ab..7739d88 100644 > >>> --- a/hw/core/machine.c > >>> +++ b/hw/core/machine.c > >>> @@ -392,6 +392,20 @@ static void machine_set_mem_merge(Object *obj, bool value, Error **errp) > >>> ms->mem_merge = value; > >>> } > >>> > >>> +static bool machine_get_memfd_alloc(Object *obj, Error **errp) > >>> +{ > >>> + MachineState *ms = MACHINE(obj); > >>> + > >>> + return ms->memfd_alloc; > >>> +} > >>> + > >>> +static void machine_set_memfd_alloc(Object *obj, bool value, Error **errp) > >>> +{ > >>> + MachineState *ms = MACHINE(obj); > >>> + > >>> + ms->memfd_alloc = value; > >>> +} > >>> + > >>> static bool machine_get_usb(Object *obj, Error **errp) > >>> { > >>> MachineState *ms = MACHINE(obj); > >>> @@ -829,6 +843,11 @@ static void machine_class_init(ObjectClass *oc, void *data) > >>> object_class_property_set_description(oc, "mem-merge", > >>> "Enable/disable memory merge support"); > >>> > >>> + object_class_property_add_bool(oc, "memfd-alloc", > >>> + machine_get_memfd_alloc, machine_set_memfd_alloc); > >>> + object_class_property_set_description(oc, "memfd-alloc", > >>> + "Enable/disable allocating anonymous memory using memfd_create"); > >>> + > >>> object_class_property_add_bool(oc, "usb", > >>> machine_get_usb, machine_set_usb); > >>> object_class_property_set_description(oc, "usb", > >>> diff --git a/include/hw/boards.h b/include/hw/boards.h > >>> index 9c1c190..a57d7a0 100644 > >>> --- a/include/hw/boards.h > >>> +++ b/include/hw/boards.h > >>> @@ -327,6 +327,7 @@ struct MachineState { > >>> char *dt_compatible; > >>> bool dump_guest_core; > >>> bool mem_merge; > >>> + bool memfd_alloc; > >>> bool usb; > >>> bool usb_disabled; > >>> char *firmware; > >>> diff --git a/qemu-options.hx b/qemu-options.hx > >>> index 7d47510..33c8173 100644 > >>> --- a/qemu-options.hx > >>> +++ b/qemu-options.hx > >>> @@ -30,6 +30,7 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \ > >>> " vmport=on|off|auto controls emulation of vmport (default: auto)\n" > >>> " dump-guest-core=on|off include guest memory in a core dump (default=on)\n" > >>> " mem-merge=on|off controls memory merge support (default: on)\n" > >>> + " memfd-alloc=on|off controls allocating anonymous guest RAM using memfd_create (default: off)\n" > >> > >> Question: are there any disadvantages associated with using > >> memfd_create? I guess we are using up an fd, but that seems minor. Any > >> reason not to set to on by default? maybe with a fallback option to > >> disable that? > > Old Linux host kernels, circa 4.1, do not support huge pages for shared memory. That doesn't matter, as we don't support any distros with kernels that old https://www.qemu.org/docs/master/about/build-platforms.html We can assume something around kernel 4.18 I believe. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|