From patchwork Fri Oct 28 09:52:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13023315 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 56AC0C38A02 for ; Fri, 28 Oct 2022 09:54:32 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ooM36-0002mj-Fp; Fri, 28 Oct 2022 05:53:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ooM31-0002dU-Mh for qemu-devel@nongnu.org; Fri, 28 Oct 2022 05:53:07 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ooM2z-0003if-Th for qemu-devel@nongnu.org; Fri, 28 Oct 2022 05:53:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666950785; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Z09OX8mf7aTaRKtsoW3ApxkW9/XaDPpq/lkwkTqpy3E=; b=IXBRknHoIRcljBDsctvSgCmFLgjm/CHXUTpRHr3kYzLwgLG/9ySR9H4YpnyiCHEMgUG84I XhaoYukLyARYyp9nEOG2ekxOAptzdzMElyfThGlooV7EQnCoMCyTH97sNUA9D01lO11pqM O39dYSCLuC19mUPzL4+PRIDqtvg8gbo= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-587-Lev_3ZDtMAaf4urqhockhA-1; Fri, 28 Oct 2022 05:53:03 -0400 X-MC-Unique: Lev_3ZDtMAaf4urqhockhA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 255633817A66; Fri, 28 Oct 2022 09:53:03 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.194.241]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4A1961400C3B; Fri, 28 Oct 2022 09:53:01 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Cc: Igor Mammedov , Xiao Guangrong , Richard Henderson , Stefan Weil , David Hildenbrand , Michal Privoznik Subject: [GIT PULL 8/8] vl: Allow ThreadContext objects to be created before the sandbox option Date: Fri, 28 Oct 2022 11:52:25 +0200 Message-Id: <20221028095225.86118-9-david@redhat.com> In-Reply-To: <20221028095225.86118-1-david@redhat.com> References: <20221028095225.86118-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Received-SPF: pass client-ip=170.10.129.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.515, 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_H2=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Qemu-devel" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Currently, there is no way to configure a CPU affinity inside QEMU when the sandbox option disables it for QEMU as a whole, for example, via: -sandbox enable=on,resourcecontrol=deny While ThreadContext objects can be created on the QEMU commandline and the CPU affinity can be configured externally via the thread-id, this is insufficient if a ThreadContext with a certain CPU affinity is already required during QEMU startup, before we can intercept QEMU and configure the CPU affinity. Blocking sched_setaffinity() was introduced in 24f8cdc57224 ("seccomp: add resourcecontrol argument to command line"), "to avoid any bigger of the process". However, we only care about once QEMU is running, not when the instance starting QEMU explicitly requests a certain CPU affinity on the QEMU comandline. Right now, for NUMA-aware preallocation of memory backends used for initial machine RAM, one has to: 1) Start QEMU with the memory-backend with "prealloc=off" 2) Pause QEMU before it starts the guest (-S) 3) Create ThreadContext, configure the CPU affinity using the thread-id 4) Configure the ThreadContext as "prealloc-context" of the memory backend 5) Trigger preallocation by setting "prealloc=on" To simplify this handling especially for initial machine RAM, allow creation of ThreadContext objects before parsing sandbox options, such that the CPU affinity requested on the QEMU commandline alongside the sandbox option can be set. As ThreadContext objects essentially only create a persistent context thread and set the CPU affinity, this is easily possible. With this change, we can create a ThreadContext with a CPU affinity on the QEMU commandline and use it for preallocation of memory backends glued to the machine (simplified example): To make "-name debug-threads=on" keep working as expected for the context threads, perform earlier parsing of "-name". qemu-system-x86_64 -m 1G \ -object thread-context,id=tc1,cpu-affinity=3-4 \ -object memory-backend-ram,id=pc.ram,size=1G,prealloc=on,prealloc-threads=2,prealloc-context=tc1 \ -machine memory-backend=pc.ram \ -S -monitor stdio -sandbox enable=on,resourcecontrol=deny And while we can query the current CPU affinity: (qemu) qom-get tc1 cpu-affinity [ 3, 4 ] We can no longer change it from QEMU directly: (qemu) qom-set tc1 cpu-affinity 1-2 Error: Setting CPU affinity failed: Operation not permitted Reviewed-by: Michal Privoznik Message-Id: <20221014134720.168738-8-david@redhat.com> Signed-off-by: David Hildenbrand --- softmmu/vl.c | 36 ++++++++++++++++++++++++++++++++---- 1 file changed, 32 insertions(+), 4 deletions(-) diff --git a/softmmu/vl.c b/softmmu/vl.c index b464da25bc..b5a23420ac 100644 --- a/softmmu/vl.c +++ b/softmmu/vl.c @@ -1759,6 +1759,27 @@ static void object_option_parse(const char *optarg) visit_free(v); } +/* + * Very early object creation, before the sandbox options have been activated. + */ +static bool object_create_pre_sandbox(const char *type) +{ + /* + * Objects should in general not get initialized "too early" without + * a reason. If you add one, state the reason in a comment! + */ + + /* + * Reason: -sandbox on,resourcecontrol=deny disallows setting CPU + * affinity of threads. + */ + if (g_str_equal(type, "thread-context")) { + return true; + } + + return false; +} + /* * Initial object creation happens before all other * QEMU data types are created. The majority of objects @@ -1773,6 +1794,11 @@ static bool object_create_early(const char *type) * add one, state the reason in a comment! */ + /* Reason: already created. */ + if (object_create_pre_sandbox(type)) { + return false; + } + /* Reason: property "chardev" */ if (g_str_equal(type, "rng-egd") || g_str_equal(type, "qtest")) { @@ -1895,7 +1921,7 @@ static void qemu_create_early_backends(void) */ static bool object_create_late(const char *type) { - return !object_create_early(type); + return !object_create_early(type) && !object_create_pre_sandbox(type); } static void qemu_create_late_backends(void) @@ -2351,6 +2377,11 @@ static int process_runstate_actions(void *opaque, QemuOpts *opts, Error **errp) static void qemu_process_early_options(void) { + qemu_opts_foreach(qemu_find_opts("name"), + parse_name, NULL, &error_fatal); + + object_option_foreach_add(object_create_pre_sandbox); + #ifdef CONFIG_SECCOMP QemuOptsList *olist = qemu_find_opts_err("sandbox", NULL); if (olist) { @@ -2358,9 +2389,6 @@ static void qemu_process_early_options(void) } #endif - qemu_opts_foreach(qemu_find_opts("name"), - parse_name, NULL, &error_fatal); - if (qemu_opts_foreach(qemu_find_opts("action"), process_runstate_actions, NULL, &error_fatal)) { exit(1);