From patchwork Fri Mar 10 02:24:25 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuang Xu X-Patchwork-Id: 13168639 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 A12D8C6FD1F for ; Fri, 10 Mar 2023 02:26:08 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1paSRU-0005fO-Jt; Thu, 09 Mar 2023 21:25:12 -0500 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 1paSRC-0005eN-4b for qemu-devel@nongnu.org; Thu, 09 Mar 2023 21:24:59 -0500 Received: from mail-pj1-x102c.google.com ([2607:f8b0:4864:20::102c]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1paSR7-0001y0-SK for qemu-devel@nongnu.org; Thu, 09 Mar 2023 21:24:51 -0500 Received: by mail-pj1-x102c.google.com with SMTP id l1so3997798pjt.2 for ; Thu, 09 Mar 2023 18:24:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1678415088; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=LnbAFlawzzcdAvvBRPDdzj3j81OcWEFdiP4smmXMd+s=; b=DieprWgRgRew+dXyufCsVgj0d50LlijffMFjhqZKc+vBW5HH4BMYPACjkuvAEJmuYZ f4/99bgSq3Vxn//Ay2n87IxglJffmGBRO3ISv44Z96ObO1Y/zgSPdSPuR/LkGsIBzjqr G/9MWbNF7llg9COoWpPnOs2rFkCd7UV1GxusnDDfocl2TEib6b2CqiYEYnBpqbWduFeY 92R4rTYKYyAljtDXLvZGh4creWQPm0TB0QHWvANtEJmGtqdmKRTA7gT9iJM62kym0lx1 Vuzka+uFxlj0YEk0ukY5uprZqDzLLv4pipqPkMOd53Xw71oF5juYJBfb1/fdok07unke 3qew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678415088; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=LnbAFlawzzcdAvvBRPDdzj3j81OcWEFdiP4smmXMd+s=; b=j/7AeAj7cx+RXXQD8+8A75hASxXMIJ2RtTc7Zc0TsXh3Yy7br6b8leT9rT9yqdYrqZ 0r2XrpKEJ2UqOiBTbSfP39p5zx3FMvp42fKjkhdMoBDB58Lxc+fgm8r0f65RIiyUk0i7 YP8IVCc4kVGRK8TG1kmsqI4r7T5HFcEXaPpWErCJlniAocW1K/x3OSxxz4vry6Cnrir9 r4Guxwv9hKdq0v2gpsdBwiA9olwrhK6mae0KuEiNMPVq59QQG0wIQSbm7qAZpfIrFx8R 9Earw6hV92AADD3NWpeqRQxiQYpt6codKve7f1bbArILMoG3ohmkgYNYJz9GXmhKvGWG Evcg== X-Gm-Message-State: AO0yUKXzEME6VR+gAHHIYg0rwoUimH6faYvfTL7CWzitRmuvoVIRwVQJ HyTwnWUMjysVhFAm7dXL2aVRsTdVWWQU9XmmwGs= X-Google-Smtp-Source: AK7set9HMN7cMugKW2H0r49hoKs1J7aGA/7PPyDgIX2Jcx0vqC8gcJPFSXgUXV3FM6DWiWIeMfXt4w== X-Received: by 2002:a05:6a20:8b23:b0:cc:5be9:fe63 with SMTP id l35-20020a056a208b2300b000cc5be9fe63mr19877271pzh.8.1678415088476; Thu, 09 Mar 2023 18:24:48 -0800 (PST) Received: from n250-032-048.byted.org ([221.194.189.28]) by smtp.gmail.com with ESMTPSA id g7-20020aa78187000000b00571f66721aesm246081pfi.42.2023.03.09.18.24.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Mar 2023 18:24:48 -0800 (PST) From: Chuang Xu To: qemu-devel@nongnu.org Cc: dgilbert@redhat.com, quintela@redhat.com, pbonzini@redhat.com, peterx@redhat.com, david@redhat.com, philmd@linaro.org, zhouyibo@bytedance.com, Chuang Xu Subject: [PATCH v7 6/6] memory: Introduce address_space_to_flatview_rcu() Date: Fri, 10 Mar 2023 10:24:25 +0800 Message-Id: <20230310022425.2992472-7-xuchuangxclwt@bytedance.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20230310022425.2992472-1-xuchuangxclwt@bytedance.com> References: <20230310022425.2992472-1-xuchuangxclwt@bytedance.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::102c; envelope-from=xuchuangxclwt@bytedance.com; helo=mail-pj1-x102c.google.com X-Spam_score_int: 4 X-Spam_score: 0.4 X-Spam_bar: / X-Spam_report: (0.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FROM_LOCAL_NOVOWEL=0.5, HK_RANDOM_ENVFROM=0.999, HK_RANDOM_FROM=1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org In last patch, we wrap vm_load with begin/commit, here we introduce address_space_to_flatview_rcu() to avoid unnecessary enforce commit during vm_load. Signed-off-by: Chuang Xu --- include/exec/memory-internal.h | 2 +- include/exec/memory.h | 20 ++++++++++++++++++++ softmmu/memory.c | 2 +- 3 files changed, 22 insertions(+), 2 deletions(-) diff --git a/include/exec/memory-internal.h b/include/exec/memory-internal.h index 100c1237ac..1432240449 100644 --- a/include/exec/memory-internal.h +++ b/include/exec/memory-internal.h @@ -30,7 +30,7 @@ static inline AddressSpaceDispatch *flatview_to_dispatch(FlatView *fv) static inline AddressSpaceDispatch *address_space_to_dispatch(AddressSpace *as) { - return flatview_to_dispatch(address_space_to_flatview(as)); + return flatview_to_dispatch(address_space_to_flatview_rcu(as)); } FlatView *address_space_get_flatview(AddressSpace *as); diff --git a/include/exec/memory.h b/include/exec/memory.h index d6fd89db64..235e3017bc 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -1100,6 +1100,9 @@ bool memory_region_transaction_in_progress(void); void memory_region_transaction_do_commit(void); +/* + * We recommend using this by default. + */ static inline FlatView *address_space_to_flatview(AddressSpace *as) { if (qemu_mutex_iothread_locked()) { @@ -1123,6 +1126,23 @@ static inline FlatView *address_space_to_flatview(AddressSpace *as) return qatomic_rcu_read(&as->current_map); } +/* + * We recommend using address_space_to_flatview() rather than this one. + * Note that if we use this during a memory region transaction, we may + * see obsolete flatviews. We must bear with an obsolete map until commit. + * And outside a memory region transaction, this is basically the same as + * address_space_to_flatview(). + */ +static inline FlatView *address_space_to_flatview_rcu(AddressSpace *as) +{ + /* + * Before using any flatview, sanity check BQL or RCU is held. + */ + assert(qemu_mutex_iothread_locked() || rcu_read_is_locked()); + + return qatomic_rcu_read(&as->current_map); +} + /** * typedef flatview_cb: callback for flatview_for_each_range() * diff --git a/softmmu/memory.c b/softmmu/memory.c index 6a8e8b4e71..33d14e967d 100644 --- a/softmmu/memory.c +++ b/softmmu/memory.c @@ -815,7 +815,7 @@ FlatView *address_space_get_flatview(AddressSpace *as) RCU_READ_LOCK_GUARD(); do { - view = address_space_to_flatview(as); + view = address_space_to_flatview_rcu(as); /* If somebody has replaced as->current_map concurrently, * flatview_ref returns false. */