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 D57B7C433DB for ; Tue, 2 Feb 2021 19:33:59 +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 737F764E39 for ; Tue, 2 Feb 2021 19:33:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 737F764E39 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]:52692 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l71R0-00037G-Gl for qemu-devel@archiver.kernel.org; Tue, 02 Feb 2021 14:33:58 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:36846) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l71O9-0008J9-Nx for qemu-devel@nongnu.org; Tue, 02 Feb 2021 14:31:01 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:55321) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l71O7-0001Fs-8y for qemu-devel@nongnu.org; Tue, 02 Feb 2021 14:31:01 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612294257; 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=aGiRvX/miiDra234/3N3CmVjK/lJzDKYceY/6z9WJE8=; b=CVdKox/ZS7qRepxacCRNnykoHd9RouUKOUDHL8jrc/CBpy3Tj0QF6sXkb8oHLEK/D05rUd PW8bydgUK0nK/jD7XiDdbQ9iRkVBcOeizDerDB/HdbOGg+6jwOsrnhV2brYzzaI+REBE8Q 4MtQNSzABFyXnyLm623luvm3aZg9g5A= 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-56-wdoEUUNeNSGxKnGM6sCnUA-1; Tue, 02 Feb 2021 14:30:54 -0500 X-MC-Unique: wdoEUUNeNSGxKnGM6sCnUA-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 3AF07C7432; Tue, 2 Feb 2021 19:30:25 +0000 (UTC) Received: from localhost (ovpn-3-197.rdu2.redhat.com [10.22.3.197]) by smtp.corp.redhat.com (Postfix) with ESMTP id 014106EF57; Tue, 2 Feb 2021 19:30:24 +0000 (UTC) From: Eduardo Habkost To: Peter Maydell , qemu-devel@nongnu.org Subject: [PULL 2/3] hostmem-file: add readonly=on|off option Date: Tue, 2 Feb 2021 14:30:19 -0500 Message-Id: <20210202193020.4107711-3-ehabkost@redhat.com> In-Reply-To: <20210202193020.4107711-1-ehabkost@redhat.com> References: <20210202193020.4107711-1-ehabkost@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=ehabkost@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=ehabkost@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.386, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: Igor Mammedov , "Michael S . Tsirkin" , Stefan Hajnoczi , Paolo Bonzini , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Stefan Hajnoczi Let -object memory-backend-file work on read-only files when the readonly=on 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. Signed-off-by: Stefan Hajnoczi Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Liam Merwick Acked-by: Michael S. Tsirkin Message-Id: <20210104171320.575838-3-stefanha@redhat.com> Signed-off-by: Eduardo Habkost --- backends/hostmem-file.c | 28 +++++++++++++++++++++++++++- qemu-options.hx | 5 ++++- 2 files changed, 31 insertions(+), 2 deletions(-) diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index e8276921244..733408e076f 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -29,6 +29,7 @@ struct HostMemoryBackendFile { uint64_t align; bool discard_data; bool is_pmem; + bool readonly; }; static void @@ -56,7 +57,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **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 } @@ -151,6 +152,28 @@ static void file_memory_backend_set_pmem(Object *o, bool value, Error **errp) fb->is_pmem = value; } +static bool file_memory_backend_get_readonly(Object *obj, Error **errp) +{ + HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj); + + return fb->readonly; +} + +static void file_memory_backend_set_readonly(Object *obj, bool value, + Error **errp) +{ + HostMemoryBackend *backend = MEMORY_BACKEND(obj); + HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj); + + if (host_memory_backend_mr_inited(backend)) { + error_setg(errp, "cannot change property 'readonly' of %s.", + object_get_typename(obj)); + return; + } + + fb->readonly = value; +} + static void file_backend_unparent(Object *obj) { HostMemoryBackend *backend = MEMORY_BACKEND(obj); @@ -182,6 +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); } static void file_backend_instance_finalize(Object *o) diff --git a/qemu-options.hx b/qemu-options.hx index d0410f05125..c09c4646e28 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4426,7 +4426,7 @@ SRST they are specified. Note that the 'id' property must be set. These objects are placed in the '/objects' path. - ``-object memory-backend-file,id=id,size=size,mem-path=dir,share=on|off,discard-data=on|off,merge=on|off,dump=on|off,prealloc=on|off,host-nodes=host-nodes,policy=default|preferred|bind|interleave,align=align`` + ``-object memory-backend-file,id=id,size=size,mem-path=dir,share=on|off,discard-data=on|off,merge=on|off,dump=on|off,prealloc=on|off,host-nodes=host-nodes,policy=default|preferred|bind|interleave,align=align,readonly=on|off`` Creates a memory file backend object, which can be used to back the guest RAM with huge pages. @@ -4509,6 +4509,9 @@ SRST 4.15) and the filesystem of ``mem-path`` mounted with DAX option. + The ``readonly`` option specifies whether the backing file is opened + read-only or read-write (default). + ``-object memory-backend-ram,id=id,merge=on|off,dump=on|off,share=on|off,prealloc=on|off,size=size,host-nodes=host-nodes,policy=default|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 -- 2.28.0