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=-15.1 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,USER_AGENT_SANE_1 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 BD93FC433B4 for ; Tue, 4 May 2021 10:31:21 +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 21CB0611AB for ; Tue, 4 May 2021 10:31:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 21CB0611AB 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]:60440 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ldsKl-0002zU-SQ for qemu-devel@archiver.kernel.org; Tue, 04 May 2021 06:31:19 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56790) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lds3A-0007cu-KR for qemu-devel@nongnu.org; Tue, 04 May 2021 06:13:10 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:55113) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lds37-0000Sh-G2 for qemu-devel@nongnu.org; Tue, 04 May 2021 06:13:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620123184; 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=F31XZ8c07tCUiTMXEoJP3omgUChlW6fAf2KPZMy/9E0=; b=dC44PDar5j6aMCwjEaDf+dj2xqJDHY6ZuphY7bQ12K/6BIJB14IVmpxAfdP7iMUf0UGvI/ u1pBKThfF4gWUaio0iWQtb+IJCNNWasOWHrFtFbOaCIXqudG4b6ytAu+LsG3IMZE+6aLEv 6fagPdUPQweAkDbcBqPr15j835ZB6t8= 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-540-7f2Lyf1LMaSW-P18v9dPfw-1; Tue, 04 May 2021 06:13:03 -0400 X-MC-Unique: 7f2Lyf1LMaSW-P18v9dPfw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F28AC8030CF; Tue, 4 May 2021 10:13:01 +0000 (UTC) Received: from redhat.com (ovpn-113-37.ams2.redhat.com [10.36.113.37]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 924925D730; Tue, 4 May 2021 10:12:41 +0000 (UTC) Date: Tue, 4 May 2021 11:12:38 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: David Hildenbrand Subject: Re: [PATCH v7 10/15] hostmem: Wire up RAM_NORESERVE via "reserve" property Message-ID: References: <20210428133754.10713-1-david@redhat.com> <20210428133754.10713-11-david@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210428133754.10713-11-david@redhat.com> User-Agent: Mutt/2.0.6 (2021-03-06) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 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: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.698, 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Marcel Apfelbaum , Eduardo Habkost , "Michael S. Tsirkin" , Richard Henderson , Markus Armbruster , Peter Xu , qemu-devel@nongnu.org, Greg Kurz , Paolo Bonzini , Stefan Hajnoczi , Murilo Opsfelder Araujo , Igor Mammedov , Nitesh Lal , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Apr 28, 2021 at 03:37:49PM +0200, David Hildenbrand wrote: > Let's provide a way to control the use of RAM_NORESERVE via memory > backends using the "reserve" property which defaults to true (old > behavior). > > Only Linux currently supports clearing the flag (and support is checked at > runtime, depending on the setting of "/proc/sys/vm/overcommit_memory"). > Windows and other POSIX systems will bail out with "reserve=false". > > The target use case is virtio-mem, which dynamically exposes memory > inside a large, sparse memory area to the VM. This essentially allows > avoiding to set "/proc/sys/vm/overcommit_memory == 0") when using > virtio-mem and also supporting hugetlbfs in the future. > > Reviewed-by: Peter Xu > Reviewed-by: Eduardo Habkost > Reviewed-by: Markus Armbruster > Acked-by: Eduardo Habkost for memory backend and machine core > Cc: Markus Armbruster > Cc: Eric Blake > Cc: Igor Mammedov > Signed-off-by: David Hildenbrand > --- > backends/hostmem-file.c | 11 ++++++----- > backends/hostmem-memfd.c | 1 + > backends/hostmem-ram.c | 1 + > backends/hostmem.c | 32 ++++++++++++++++++++++++++++++++ > include/sysemu/hostmem.h | 2 +- > qapi/qom.json | 10 ++++++++++ > 6 files changed, 51 insertions(+), 6 deletions(-) > > diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c > index b683da9daf..9d550e53d4 100644 > --- a/backends/hostmem-file.c > +++ b/backends/hostmem-file.c > @@ -40,6 +40,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) > object_get_typename(OBJECT(backend))); > #else > HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend); > + uint32_t ram_flags; > gchar *name; > > if (!backend->size) { > @@ -52,11 +53,11 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) > } > > name = host_memory_backend_get_name(backend); > - memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), > - name, > - backend->size, fb->align, > - (backend->share ? RAM_SHARED : 0) | > - (fb->is_pmem ? RAM_PMEM : 0), > + ram_flags = backend->share ? RAM_SHARED : 0; > + ram_flags |= backend->reserve ? 0 : RAM_NORESERVE; > + ram_flags |= fb->is_pmem ? RAM_PMEM : 0; > + memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), name, > + backend->size, fb->align, ram_flags, > fb->mem_path, fb->readonly, errp); > g_free(name); > #endif > diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c > index 93b5d1a4cf..f3436b623d 100644 > --- a/backends/hostmem-memfd.c > +++ b/backends/hostmem-memfd.c > @@ -55,6 +55,7 @@ memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) > > name = host_memory_backend_get_name(backend); > ram_flags = backend->share ? RAM_SHARED : 0; > + ram_flags |= backend->reserve ? 0 : RAM_NORESERVE; > memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name, > backend->size, ram_flags, fd, 0, errp); > g_free(name); > diff --git a/backends/hostmem-ram.c b/backends/hostmem-ram.c > index 741e701062..b8e55cdbd0 100644 > --- a/backends/hostmem-ram.c > +++ b/backends/hostmem-ram.c > @@ -29,6 +29,7 @@ ram_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) > > name = host_memory_backend_get_name(backend); > ram_flags = backend->share ? RAM_SHARED : 0; > + ram_flags |= backend->reserve ? 0 : RAM_NORESERVE; > memory_region_init_ram_flags_nomigrate(&backend->mr, OBJECT(backend), name, > backend->size, ram_flags, errp); > g_free(name); > diff --git a/backends/hostmem.c b/backends/hostmem.c > index c6c1ff5b99..58fdc1b658 100644 > --- a/backends/hostmem.c > +++ b/backends/hostmem.c > @@ -217,6 +217,11 @@ static void host_memory_backend_set_prealloc(Object *obj, bool value, > Error *local_err = NULL; > HostMemoryBackend *backend = MEMORY_BACKEND(obj); > > + if (!backend->reserve && value) { > + error_setg(errp, "'prealloc=on' and 'reserve=off' are incompatible"); > + return; > + } > + > if (!host_memory_backend_mr_inited(backend)) { > backend->prealloc = value; > return; > @@ -268,6 +273,7 @@ static void host_memory_backend_init(Object *obj) > /* TODO: convert access to globals to compat properties */ > backend->merge = machine_mem_merge(machine); > backend->dump = machine_dump_guest_core(machine); > + backend->reserve = true; > backend->prealloc_threads = 1; > } > > @@ -426,6 +432,28 @@ static void host_memory_backend_set_share(Object *o, bool value, Error **errp) > backend->share = value; > } > > +static bool host_memory_backend_get_reserve(Object *o, Error **errp) > +{ > + HostMemoryBackend *backend = MEMORY_BACKEND(o); > + > + return backend->reserve; > +} > + > +static void host_memory_backend_set_reserve(Object *o, bool value, Error **errp) > +{ > + HostMemoryBackend *backend = MEMORY_BACKEND(o); > + > + if (host_memory_backend_mr_inited(backend)) { > + error_setg(errp, "cannot change property value"); > + return; > + } > + if (backend->prealloc && !value) { > + error_setg(errp, "'prealloc=on' and 'reserve=off' are incompatible"); > + return; > + } > + backend->reserve = value; > +} > + > static bool > host_memory_backend_get_use_canonical_path(Object *obj, Error **errp) > { > @@ -494,6 +522,10 @@ host_memory_backend_class_init(ObjectClass *oc, void *data) > host_memory_backend_get_share, host_memory_backend_set_share); > object_class_property_set_description(oc, "share", > "Mark the memory as private to QEMU or shared"); > + object_class_property_add_bool(oc, "reserve", > + host_memory_backend_get_reserve, host_memory_backend_set_reserve); > + object_class_property_set_description(oc, "reserve", > + "Reserve swap space (or huge pages) if applicable"); > /* > * Do not delete/rename option. This option must be considered stable > * (as if it didn't have the 'x-' prefix including deprecation period) as > diff --git a/include/sysemu/hostmem.h b/include/sysemu/hostmem.h > index df5644723a..9ff5c16963 100644 > --- a/include/sysemu/hostmem.h > +++ b/include/sysemu/hostmem.h > @@ -64,7 +64,7 @@ struct HostMemoryBackend { > /* protected */ > uint64_t size; > bool merge, dump, use_canonical_path; > - bool prealloc, is_mapped, share; > + bool prealloc, is_mapped, share, reserve; > uint32_t prealloc_threads; > DECLARE_BITMAP(host_nodes, MAX_NODES + 1); > HostMemPolicy policy; > diff --git a/qapi/qom.json b/qapi/qom.json > index cd0e76d564..4fa3137aab 100644 > --- a/qapi/qom.json > +++ b/qapi/qom.json > @@ -545,6 +545,9 @@ > # @share: if false, the memory is private to QEMU; if true, it is shared > # (default: false) > # > +# @reserve: if true, reserve swap space (or huge pages) if applicable > +# default: true) > +# > # @size: size of the memory region in bytes > # > # @x-use-canonical-path-for-ramblock-id: if true, the canoncial path is used > @@ -556,6 +559,12 @@ > # false generally, but true for machine > # types <= 4.0) > # > +# Note: prealloc=true and reserve=false cannot be set at the same time. With > +# reserve=true, the behavior depends on the operating system: for example, > +# Linux will not reserve swap space for shared file mappings -- > +# "not applicable". In contrast, reserve=false will bail out if it cannot > +# be configured accordingly. > +# > # Since: 2.1 > ## > { 'struct': 'MemoryBackendProperties', > @@ -566,6 +575,7 @@ > '*prealloc': 'bool', > '*prealloc-threads': 'uint32', > '*share': 'bool', > + '*reserve': 'bool', > 'size': 'size', > '*x-use-canonical-path-for-ramblock-id': 'bool' } } IIUC from the previous patch in the series, 'reserve' is only implemented on Linux. If we make this QAPI prop dependant on CONFIG_LINUX, then mgmt apps will do the right thing to detect what platform(s) it works on. 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 :|