From nobody Tue Dec 23 15:36:35 2025 Delivered-To: importer2@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer2=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=nongnu.org ARC-Seal: i=1; a=rsa-sha256; t=1718324468; cv=none; d=zohomail.com; s=zohoarc; b=aQP7jt+evmXpz6NxfiMMn3ZkTIdvFkqzpYw+0XfbBuLFr7jAJV/sr7D3Br6mZYhvmx/CHnEAsXJri1nGhQhVrb0ABnAbrAyliBEzqwqa4wrblsDT419gyIhZ1KlLJtBkohUrTCriP8URPI6KXDiMvQTSjjYocHE49xx3q2kvuUI= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1718324468; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:Reply-To:Reply-To:References:Sender:Subject:Subject:To:To:Message-Id; bh=0WunhJNZi3PqNB869tBtSDMqQ/41cwjXIohhpfE+DLs=; b=mOCUo3r5OSEqeB1vg8Z3tQKh+6WiCagcUoc39FEjXLMNozwPfYnUSkgjvh1cFDwkmudIIxxdDZmk//swTscNfEQHuCuCS7QxPBEKAF1UN6edHU4emPetampPU56/8WS2FVwuOyyUJUIgZtst/cBiom1EUzyMsvligAoObio0yP4= ARC-Authentication-Results: i=1; mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer2=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1718324468727763.8710352624722; Thu, 13 Jun 2024 17:21:08 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sHugC-0004Su-W9; Thu, 13 Jun 2024 20:20:33 -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 1sHugB-0004ST-96; Thu, 13 Jun 2024 20:20:31 -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 1sHug9-0002g0-AP; Thu, 13 Jun 2024 20:20:31 -0400 Received: from mail.maildlp.com (unknown [172.18.186.31]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4W0g0L2mDyz6K61G; Fri, 14 Jun 2024 08:20:18 +0800 (CST) Received: from lhrpeml500001.china.huawei.com (unknown [7.191.163.213]) by mail.maildlp.com (Postfix) with ESMTPS id 521B7140594; Fri, 14 Jun 2024 08:20:21 +0800 (CST) Received: from 00293818-MRGF.china.huawei.com (10.195.245.24) by lhrpeml500001.china.huawei.com (7.191.163.213) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Fri, 14 Jun 2024 01:19:58 +0100 To: , , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH RFC V3 28/29] tcg/mttcg: enable threads to unregister in tcg_ctxs[] Date: Fri, 14 Jun 2024 01:19:44 +0100 Message-ID: <20240614001944.203038-1-salil.mehta@huawei.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240613233639.202896-1-salil.mehta@huawei.com> References: <20240613233639.202896-1-salil.mehta@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.195.245.24] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To lhrpeml500001.china.huawei.com (7.191.163.213) Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer2=patchew.org@nongnu.org; helo=lists.gnu.org; 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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+importer2=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer2=patchew.org@nongnu.org X-ZM-MESSAGEID: 1718324470657100003 Content-Type: text/plain; charset="utf-8" From: Miguel Luis [BROKEN: This patch is just for reference. It has problems as it does not t= akes care of the TranslationBlocks and their assigned regions during CPU unreali= ze] When using TCG acceleration in a multi-threaded context each vCPU has its o= wn thread registered in tcg_ctxs[] upon creation and tcg_cur_ctxs stores the c= urrent 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, ther= efore breaking the assert stating tcg_cur_ctxs < tcg_max_ctxs after a certain amo= unt 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/startup.h | 7 +++++++ tcg/tcg.c | 24 ++++++++++++++++++++++++ 3 files changed, 32 insertions(+) diff --git a/accel/tcg/tcg-accel-ops-mttcg.c b/accel/tcg/tcg-accel-ops-mttc= g.c index c552b45b8e..b6d7911a87 100644 --- a/accel/tcg/tcg-accel-ops-mttcg.c +++ b/accel/tcg/tcg-accel-ops-mttcg.c @@ -122,6 +122,7 @@ static void *mttcg_cpu_thread_fn(void *arg) bql_unlock(); rcu_remove_force_rcu_notifier(&force_rcu.notifier); rcu_unregister_thread(); + tcg_unregister_thread(); return NULL; } =20 diff --git a/include/tcg/startup.h b/include/tcg/startup.h index f71305765c..dc35b24de5 100644 --- a/include/tcg/startup.h +++ b/include/tcg/startup.h @@ -45,6 +45,13 @@ void tcg_init(size_t tb_size, int splitwx, unsigned max_= cpus); */ void tcg_register_thread(void); =20 +/** + * tcg_unregister_thread: Unregister this thread with the TCG runtime + * + * TBD + */ +void tcg_unregister_thread(void); + /** * tcg_prologue_init(): Generate the code for the TCG prologue * diff --git a/tcg/tcg.c b/tcg/tcg.c index 34e3056380..e5bbe8dc07 100644 --- a/tcg/tcg.c +++ b/tcg/tcg.c @@ -761,6 +761,15 @@ QEMU_BUILD_BUG_ON((int)(offsetof(CPUNegativeOffsetStat= e, tlb.f[0]) - < MIN_TLB_MASK_TABLE_OFS); #endif =20 +/* TODO: vCPU Hotplug: Need to come back and fix the TCG */ +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 functi= on @@ -810,6 +819,21 @@ void tcg_register_thread(void) =20 tcg_ctx =3D s; } + +void tcg_unregister_thread(void) +{ + TCGContext *s =3D tcg_ctx; + unsigned int n; + + /* Unclaim an entry in tcg_ctxs */ + n =3D 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 */ =20 /* pool based memory allocation */ --=20 2.34.1