From nobody Mon Feb 9 23:04:15 2026 Received: from szxga07-in.huawei.com (szxga07-in.huawei.com [45.249.212.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 260FA1BD006 for ; Tue, 6 Aug 2024 08:59:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.35 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722934776; cv=none; b=tA89zsRJjWdV5Kg4s9Q36T3FUOhAFCjHMSS9gpVkuUyBh+bedSid41NdOIi+Ovi0Y7nyMYR8enakMJbLt7xjwr24eaD1m7tAbfuddxyhW7d0BwCG/AdA+cNwNr5Q0F7gA6hFOMmrj+DS22GXsrm+TyiVq7Yx5bWZntT4H3oO/Uc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722934776; c=relaxed/simple; bh=WDF/r+6egignnSjHAddYiXtfN1ZrKWnOTd2V0MS7O+s=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=e/0+AsM7vv2+jwGoP9zxMPieoWamPh8/aKekY0tXPX5CHERsP9DeWkVV23qIjoUD3dEgbYAkmWTbjzvOS3YHqCSrlOrLVV/iW+0wWoil8QmWORGY9n+ObGKNYEHEk9IMoRdXpEqSUxcvLmnb58P7EKBuuLl7iVdU744gq/SJMVs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.35 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.162.112]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4WdRvY33Zqz1S76G; Tue, 6 Aug 2024 16:54:49 +0800 (CST) Received: from kwepemd200014.china.huawei.com (unknown [7.221.188.8]) by mail.maildlp.com (Postfix) with ESMTPS id 5645B140157; Tue, 6 Aug 2024 16:59:31 +0800 (CST) Received: from localhost.localdomain (10.50.165.33) by kwepemd200014.china.huawei.com (7.221.188.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.34; Tue, 6 Aug 2024 16:59:30 +0800 From: Yicong Yang To: , , , , , , , , , CC: , , , , , , , , , , , Subject: [PATCH v5 1/4] cpu/SMT: Provide a default topology_is_primary_thread() Date: Tue, 6 Aug 2024 16:53:17 +0800 Message-ID: <20240806085320.63514-2-yangyicong@huawei.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20240806085320.63514-1-yangyicong@huawei.com> References: <20240806085320.63514-1-yangyicong@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemd200014.china.huawei.com (7.221.188.8) Content-Type: text/plain; charset="utf-8" From: Yicong Yang Currently if architectures want to support HOTPLUG_SMT they need to provide a topology_is_primary_thread() telling the framework which thread in the SMT cannot offline. However arm64 doesn't have a restriction on which thread in the SMT cannot offline, a simplest choice is that just make 1st thread as the "primary" thread. So just make this as the default implementation in the framework and let architectures like x86 that have special primary thread to override this function. There's no need to provide a stub function if !CONFIG_SMP or !CONFIG_HOTPLUG_SMP. In such case the testing CPU is already the 1st CPU in the SMT so it's always the primary thread. Signed-off-by: Yicong Yang --- arch/powerpc/include/asm/topology.h | 1 + arch/x86/include/asm/topology.h | 2 +- include/linux/topology.h | 14 ++++++++++++++ 3 files changed, 16 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm= /topology.h index f4e6f2dd04b7..e0971777f2d9 100644 --- a/arch/powerpc/include/asm/topology.h +++ b/arch/powerpc/include/asm/topology.h @@ -151,6 +151,7 @@ static inline bool topology_is_primary_thread(unsigned = int cpu) { return cpu =3D=3D cpu_first_thread_sibling(cpu); } +#define topology_is_primary_thread topology_is_primary_thread =20 static inline bool topology_smt_thread_allowed(unsigned int cpu) { diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topolog= y.h index abe3a8f22cbd..86c077f8ee99 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -219,11 +219,11 @@ static inline bool topology_is_primary_thread(unsigne= d int cpu) { return cpumask_test_cpu(cpu, cpu_primary_thread_mask); } +#define topology_is_primary_thread topology_is_primary_thread =20 #else /* CONFIG_SMP */ static inline int topology_phys_to_logical_pkg(unsigned int pkg) { return = 0; } static inline int topology_max_smt_threads(void) { return 1; } -static inline bool topology_is_primary_thread(unsigned int cpu) { return t= rue; } static inline unsigned int topology_amd_nodes_per_pkg(void) { return 1; } #endif /* !CONFIG_SMP */ =20 diff --git a/include/linux/topology.h b/include/linux/topology.h index 52f5850730b3..9c9f6b9f3462 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -240,6 +240,20 @@ static inline const struct cpumask *cpu_smt_mask(int c= pu) } #endif =20 +#ifndef topology_is_primary_thread +#define topology_is_primary_thread topology_is_primary_thread +static inline bool topology_is_primary_thread(unsigned int cpu) +{ + /* + * On SMT hotplug the primary thread of the SMT won't be disabled. + * Architectures do have a special primary thread (e.g. x86) need + * to override this function. Otherwise just make the first thread + * in the SMT as the primary thread. + */ + return cpu =3D=3D cpumask_first(topology_sibling_cpumask(cpu)); +} +#endif + static inline const struct cpumask *cpu_cpu_mask(int cpu) { return cpumask_of_node(cpu_to_node(cpu)); --=20 2.24.0