From patchwork Thu Feb 9 15:41:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13134778 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2381DC636D7 for ; Thu, 9 Feb 2023 15:42:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231565AbjBIPmv (ORCPT ); Thu, 9 Feb 2023 10:42:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54946 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231563AbjBIPmk (ORCPT ); Thu, 9 Feb 2023 10:42:40 -0500 Received: from mail-wm1-x32d.google.com (mail-wm1-x32d.google.com [IPv6:2a00:1450:4864:20::32d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1024A643D9 for ; Thu, 9 Feb 2023 07:42:05 -0800 (PST) Received: by mail-wm1-x32d.google.com with SMTP id f47-20020a05600c492f00b003dc584a7b7eso4166605wmp.3 for ; Thu, 09 Feb 2023 07:42:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; 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=L+woZryxcmbb99mupmnna5okozeg16DDHF5Mj8G3upM=; b=gih0aal19S9nSzdM2EI39YXMR5nl2xJGmtK0jzTE06zlTaPK55Qd3mmQbuA+cqaMfi UKiLU5aZy7tn5ia+NmqWiU2EIpJXjm+fDDGunmntxWjZlIjdBS/kvJd5YQuENxMxYm+c AFCdDwoZNSl8QxCX/2NWvs67wm2cgNRqbNfWyER2oudQkCZDjotapvk0Oq2ROv0FFMgP XmfClELw1Wf9sqYOdjcclv1gsharUtQT3NQ8ATagCEfGaKpyiP0YzWR6Cmxn3OclvS6T 5EBXLwFqCjBILNmTwK63SbEhYwRJSJC+ssLE0iWqSWJRAAZbpJuQ+VdlW+sY17OQEiAl oASQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; 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=L+woZryxcmbb99mupmnna5okozeg16DDHF5Mj8G3upM=; b=wtmQIE92JSXTZG4cOhfid5sGdFaLNv1tBmbSjJGxc6SQbksNuphrH53gLSWIHzxT1A tmCQGgWADTS6W9m/P/g+hYaMBb7vVMIJ87ep2DDUSxixEW7DIRm79kEP08vcttFVu9TD 4i+cyBXRzo02t+QYbukFJyuZ+92NarJstCIIedPYSFr5X/cKeSFT+GsQBaWT4nn0RbT9 AYnVR0uZ9O94yAwj96Bbs5Gu1SnK1dPATtDlIrltwkt3x4wElS3UzGk2lMLYJYV9rawo NvR7jXuDrWF5qoJ/9X1Sj2WIQyfA5718gl1/tpbTcrYpAEPLLnp98rfxJMOuyFxyDOAI hevg== X-Gm-Message-State: AO0yUKXWlohQ9R+Mw52EV9woMahFqS0i3l0gVOsjfWh2+X9mUbdD3YIR zkzj4B93NeuWUQ4yKngrZHhfAQ== X-Google-Smtp-Source: AK7set/sWgTNchnuaYWjizrQWtBx268zZySwi/F8bUcd1EeZGHrZZweHAtzLqOUWHa4cn1YWsuFIWg== X-Received: by 2002:a05:600c:3298:b0:3dd:1c45:a36d with SMTP id t24-20020a05600c329800b003dd1c45a36dmr4683343wmp.27.1675957323675; Thu, 09 Feb 2023 07:42:03 -0800 (PST) Received: from usaari01.cust.communityfibre.co.uk ([2a02:6b6a:b566:0:8009:2525:9580:8db2]) by smtp.gmail.com with ESMTPSA id y6-20020a05600c364600b003df7b40f99fsm5099754wmq.11.2023.02.09.07.42.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Feb 2023 07:42:03 -0800 (PST) From: Usama Arif To: dwmw2@infradead.org, tglx@linutronix.de, kim.phillips@amd.com Cc: arjan@linux.intel.com, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com, paulmck@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de, hewenliang4@huawei.com, thomas.lendacky@amd.com, seanjc@google.com, pmenzel@molgen.mpg.de, fam.zheng@bytedance.com, punit.agrawal@bytedance.com, simon.evans@bytedance.com, liangma@liangbit.com, David Woodhouse , Usama Arif Subject: [PATCH v8 4/9] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() Date: Thu, 9 Feb 2023 15:41:51 +0000 Message-Id: <20230209154156.266385-5-usama.arif@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230209154156.266385-1-usama.arif@bytedance.com> References: <20230209154156.266385-1-usama.arif@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: David Woodhouse When bringing up a secondary CPU from do_boot_cpu(), the warm reset flag is set in CMOS and the starting IP for the trampoline written inside the BDA at 0x467. Once the CPU is running, the CMOS flag is unset and the value in the BDA cleared. To allow for parallel bringup of CPUs, add a reference count to track the number of CPUs currently bring brought up, and clear the state only when the count reaches zero. Since the RTC spinlock is required to write to the CMOS, it can be used for mutual exclusion on the refcount too. [Usama Arif: fixed rebase conflict] Signed-off-by: David Woodhouse Signed-off-by: Usama Arif --- arch/x86/kernel/smpboot.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 55cad72715d9..3a793772a2aa 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -121,17 +121,20 @@ int arch_update_cpu_topology(void) return retval; } + +static unsigned int smpboot_warm_reset_vector_count; + static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip) { unsigned long flags; spin_lock_irqsave(&rtc_lock, flags); - CMOS_WRITE(0xa, 0xf); + if (!smpboot_warm_reset_vector_count++) { + CMOS_WRITE(0xa, 0xf); + *((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_HIGH)) = start_eip >> 4; + *((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) = start_eip & 0xf; + } spin_unlock_irqrestore(&rtc_lock, flags); - *((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_HIGH)) = - start_eip >> 4; - *((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) = - start_eip & 0xf; } static inline void smpboot_restore_warm_reset_vector(void) @@ -143,10 +146,12 @@ static inline void smpboot_restore_warm_reset_vector(void) * to default values. */ spin_lock_irqsave(&rtc_lock, flags); - CMOS_WRITE(0, 0xf); + if (!--smpboot_warm_reset_vector_count) { + CMOS_WRITE(0, 0xf); + *((volatile u32 *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) = 0; + } spin_unlock_irqrestore(&rtc_lock, flags); - *((volatile u32 *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) = 0; } /*