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 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 3195FE7D27F for ; Tue, 26 Sep 2023 10:39:13 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ql5Sz-0006C0-3v; Tue, 26 Sep 2023 06:38:57 -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 1ql5Su-00060K-CS; Tue, 26 Sep 2023 06:38:52 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ql5Ss-00020o-FN; Tue, 26 Sep 2023 06:38:52 -0400 Received: from lhrpeml500001.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Rvx5V3z5Pz6K8jp; Tue, 26 Sep 2023 18:37:34 +0800 (CST) Received: from A190218597.china.huawei.com (10.126.174.16) by lhrpeml500001.china.huawei.com (7.191.163.213) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Tue, 26 Sep 2023 11:38:30 +0100 To: , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH RFC V2 36/37] tcg/mttcg: enable threads to unregister in tcg_ctxs[] Date: Tue, 26 Sep 2023 11:36:53 +0100 Message-ID: <20230926103654.34424-5-salil.mehta@huawei.com> X-Mailer: git-send-email 2.8.3 In-Reply-To: <20230926103654.34424-1-salil.mehta@huawei.com> References: <20230926100436.28284-1-salil.mehta@huawei.com> <20230926103654.34424-1-salil.mehta@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.126.174.16] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To lhrpeml500001.china.huawei.com (7.191.163.213) X-CFilter-Loop: Reflected Received-SPF: pass client-ip=185.176.79.56; envelope-from=salil.mehta@huawei.com; helo=frasgout.his.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H5=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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-to: Salil Mehta From: Salil Mehta via Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Miguel Luis [This patch is just for reference. It has problems as it does not takes care of the TranslationBlocks and their assigned regions during CPU unrealize] When using TCG acceleration in a multi-threaded context each vCPU has its own thread registered in tcg_ctxs[] upon creation and tcg_cur_ctxs stores the current number of threads that got created. Although, the lack of a mechanism to unregister these threads is a problem when exercising vCPU hotplug/unplug due to the fact that tcg_cur_ctxs gets incremented everytime a vCPU gets hotplugged but never gets decremented everytime a vCPU gets unplugged, therefore breaking the assert stating tcg_cur_ctxs < tcg_max_ctxs after a certain amount of vCPU hotplugs. Suggested-by: Salil Mehta [SM: Check Things To Do Section, https://lore.kernel.org/all/20200613213629.21984-1-salil.mehta@huawei.com/] Signed-off-by: Miguel Luis --- accel/tcg/tcg-accel-ops-mttcg.c | 1 + include/tcg/tcg.h | 1 + tcg/tcg.c | 23 +++++++++++++++++++++++ 3 files changed, 25 insertions(+) diff --git a/accel/tcg/tcg-accel-ops-mttcg.c b/accel/tcg/tcg-accel-ops-mttcg.c index b276262007..5cf9747ef2 100644 --- a/accel/tcg/tcg-accel-ops-mttcg.c +++ b/accel/tcg/tcg-accel-ops-mttcg.c @@ -127,6 +127,7 @@ static void *mttcg_cpu_thread_fn(void *arg) qemu_mutex_unlock_iothread(); rcu_remove_force_rcu_notifier(&force_rcu.notifier); rcu_unregister_thread(); + tcg_unregister_thread(); return NULL; } diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h index 0875971719..6c1cd2a618 100644 --- a/include/tcg/tcg.h +++ b/include/tcg/tcg.h @@ -785,6 +785,7 @@ static inline void *tcg_malloc(int size) void tcg_init(size_t tb_size, int splitwx, unsigned max_cpus); void tcg_register_thread(void); +void tcg_unregister_thread(void); void tcg_prologue_init(TCGContext *s); void tcg_func_start(TCGContext *s); diff --git a/tcg/tcg.c b/tcg/tcg.c index ddfe9a96cb..6760f40823 100644 --- a/tcg/tcg.c +++ b/tcg/tcg.c @@ -742,6 +742,14 @@ static void alloc_tcg_plugin_context(TCGContext *s) #endif } +static void free_tcg_plugin_context(TCGContext *s) +{ +#ifdef CONFIG_PLUGIN + g_ptr_array_unref(s->plugin_tb->insns); + g_free(s->plugin_tb); +#endif +} + /* * All TCG threads except the parent (i.e. the one that called tcg_context_init * and registered the target's TCG globals) must register with this function @@ -791,6 +799,21 @@ void tcg_register_thread(void) tcg_ctx = s; } + +void tcg_unregister_thread(void) +{ + TCGContext *s = tcg_ctx; + unsigned int n; + + /* Unclaim an entry in tcg_ctxs */ + n = qatomic_fetch_dec(&tcg_cur_ctxs); + g_assert(n > 1); + qatomic_store_release(&tcg_ctxs[n - 1], 0); + + free_tcg_plugin_context(s); + + g_free(s); +} #endif /* !CONFIG_USER_ONLY */ /* pool based memory allocation */ -- 2.34.1