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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 9EBE6C4361B for ; Mon, 14 Dec 2020 11:11:51 +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 0FE44229C5 for ; Mon, 14 Dec 2020 11:11:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0FE44229C5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:49640 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kolld-0002LQ-NR for qemu-devel@archiver.kernel.org; Mon, 14 Dec 2020 06:11:49 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:52672) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kolkQ-0001kA-6P for qemu-devel@nongnu.org; Mon, 14 Dec 2020 06:10:35 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:31123) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kolkM-0007Bh-Jd for qemu-devel@nongnu.org; Mon, 14 Dec 2020 06:10:33 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607944229; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=zaHNqBQN7bP4Yx//r4S9EEcBi7KblCYq/DjpfHFzOYY=; b=OpxCosJfm6qwC+rWaATCUnhIjg6AvN9XJ9+v4gtvyykorE6lt4rV9kotQzDsDwB0rJJmcz K2rB2MUBsUs/0lY1FI+bOtm5j4i/ZKr7tuCcQLA42wmEydlQivOognH/AlK9MKZXvm5/S7 EH8Va05TbMriZOdZ9h8s4AUm/75ikN4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-309-QadmP2xnNqy3_jIfBVJvYA-1; Mon, 14 Dec 2020 06:10:28 -0500 X-MC-Unique: QadmP2xnNqy3_jIfBVJvYA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F24D11005504; Mon, 14 Dec 2020 11:10:26 +0000 (UTC) Received: from localhost (unknown [10.40.208.9]) by smtp.corp.redhat.com (Postfix) with ESMTP id E69321C930; Mon, 14 Dec 2020 11:10:17 +0000 (UTC) Date: Mon, 14 Dec 2020 12:10:15 +0100 From: Igor Mammedov To: Stefan Hajnoczi Subject: Re: [PATCH v2 2/3] hostmem-file: add readonly=on|off option Message-ID: <20201214121015.592aaef0@redhat.com> In-Reply-To: <20200916095150.755714-3-stefanha@redhat.com> References: <20200916095150.755714-1-stefanha@redhat.com> <20200916095150.755714-3-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=imammedo@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=216.205.24.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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: Eduardo Habkost , "Michael S. Tsirkin" , Julio Montes , Xiao Guangrong , qemu-devel@nongnu.org, eric.g.ernst@gmail.com, Paolo Bonzini , Philippe =?UTF-8?B?TWF0aGlldS1EYXVkw6k=?= , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 16 Sep 2020 10:51:49 +0100 Stefan Hajnoczi wrote: > Let -object memory-backend-file work on read-only files when the > readonly=3Don option is given. This can be used to share the contents of = a > file between multiple guests while preventing them from consuming > Copy-on-Write memory if guests dirty the pages, for example. >=20 > Acked-by: Michael S. Tsirkin > Reviewed-by: Philippe Mathieu-Daud=C3=A9 > Signed-off-by: Stefan Hajnoczi cosmetic/style nits only s/Object *o/Object *obj/ for consistency with the rest of the code in file. > --- > backends/hostmem-file.c | 26 +++++++++++++++++++++++++- > qemu-options.hx | 5 ++++- > 2 files changed, 29 insertions(+), 2 deletions(-) >=20 > diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c > index dffdf142e0..da585e4300 100644 > --- a/backends/hostmem-file.c > +++ b/backends/hostmem-file.c > @@ -31,6 +31,7 @@ struct HostMemoryBackendFile { > uint64_t align; > bool discard_data; > bool is_pmem; > + bool readonly; > }; > =20 > static void > @@ -58,7 +59,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, E= rror **errp) > backend->size, fb->align, > (backend->share ? RAM_SHARED : 0) | > (fb->is_pmem ? RAM_PMEM : 0), > - fb->mem_path, false, errp); > + fb->mem_path, fb->readonly, errp); > g_free(name); > #endif > } > @@ -153,6 +154,26 @@ static void file_memory_backend_set_pmem(Object *o, = bool value, Error **errp) > fb->is_pmem =3D value; > } > =20 > +static bool file_memory_backend_get_readonly(Object *o, Error **errp) > +{ > + return MEMORY_BACKEND_FILE(o)->readonly; I thought using macro this way not acceptable and one should use HostMemoryBackendFile *fb =3D MEMORY_BACKEND_FILE(o); return fb->readonly; > +} > + > +static void file_memory_backend_set_readonly(Object *o, bool value, > + Error **errp) > +{ > + HostMemoryBackend *backend =3D MEMORY_BACKEND(o); > + HostMemoryBackendFile *fb =3D MEMORY_BACKEND_FILE(o); > + > + if (host_memory_backend_mr_inited(backend)) { > + error_setg(errp, "cannot change property 'readonly' of %s.", > + object_get_typename(o)); > + return; > + } > + > + fb->readonly =3D value; > +} > + > static void file_backend_unparent(Object *obj) > { > HostMemoryBackend *backend =3D MEMORY_BACKEND(obj); > @@ -184,6 +205,9 @@ file_backend_class_init(ObjectClass *oc, void *data) > NULL, NULL); > object_class_property_add_bool(oc, "pmem", > file_memory_backend_get_pmem, file_memory_backend_set_pmem); > + object_class_property_add_bool(oc, "readonly", > + file_memory_backend_get_readonly, > + file_memory_backend_set_readonly); > } > =20 > static void file_backend_instance_finalize(Object *o) > diff --git a/qemu-options.hx b/qemu-options.hx > index b0f020594e..3dfaaddd62 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -4369,7 +4369,7 @@ SRST > they are specified. Note that the 'id' property must be set. These > objects are placed in the '/objects' path. > =20 > - ``-object memory-backend-file,id=3Did,size=3Dsize,mem-path=3Ddir,sha= re=3Don|off,discard-data=3Don|off,merge=3Don|off,dump=3Don|off,prealloc=3Do= n|off,host-nodes=3Dhost-nodes,policy=3Ddefault|preferred|bind|interleave,al= ign=3Dalign`` > + ``-object memory-backend-file,id=3Did,size=3Dsize,mem-path=3Ddir,sha= re=3Don|off,discard-data=3Don|off,merge=3Don|off,dump=3Don|off,prealloc=3Do= n|off,host-nodes=3Dhost-nodes,policy=3Ddefault|preferred|bind|interleave,al= ign=3Dalign,readonly=3Don|off`` > Creates a memory file backend object, which can be used to back > the guest RAM with huge pages. > =20 > @@ -4452,6 +4452,9 @@ SRST > 4.15) and the filesystem of ``mem-path`` mounted with DAX > option. > =20 > + The ``readonly`` option specifies whether the backing file is op= ened > + read-only or read-write (default). > + > ``-object memory-backend-ram,id=3Did,merge=3Don|off,dump=3Don|off,sh= are=3Don|off,prealloc=3Don|off,size=3Dsize,host-nodes=3Dhost-nodes,policy= =3Ddefault|preferred|bind|interleave`` > Creates a memory backend object, which can be used to back the > guest RAM. Memory backend objects offer more control than the