From patchwork Tue Feb 7 23:04:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13132195 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 4B2CDC64EC5 for ; Tue, 7 Feb 2023 23:04:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229632AbjBGXEu (ORCPT ); Tue, 7 Feb 2023 18:04:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49020 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230037AbjBGXEr (ORCPT ); Tue, 7 Feb 2023 18:04:47 -0500 Received: from mail-wr1-x430.google.com (mail-wr1-x430.google.com [IPv6:2a00:1450:4864:20::430]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C90C63FF33 for ; Tue, 7 Feb 2023 15:04:45 -0800 (PST) Received: by mail-wr1-x430.google.com with SMTP id i5so7917272wrc.0 for ; Tue, 07 Feb 2023 15:04:45 -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=I6OGmp/zf+SXm16RpuuHG0Cs0grAvvCacNPO9dKsk1CnGRmdMFu6+0NJdJhyZFTM4X t222CAl7UR84WcZsi9vxKoozrPUuo3JLOzCIH9sxnbaS2E1xVnpxE5522R2XhnSGXoAq H4dMxa2K3aJcC4yIroI+hFKQ3ShkEp8NGiIlepnXYdQeZXr63YjWL9GWbYxgDjB8SqFq 6hSMRm3TCfJwjZPwZVHhxdN9/3ajo3kOYvz8TDCXvwpUD7+G2VBebFw/w20A52rvxJgq tohCQW4m433T31Ja45QB9CYTeV4/Ljp7ac0MTuuxzvTX9xUgS2fkFqmLhmlrsnEBHe/T tISw== 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=zXUbP2WOMEyG3DH25Ib8NsJOPf1JZZZuTHNT32+Zs9n3Wv4ouWB55TUxe3DdOsaGho 3lTyr4EXy8VnVD8PUMXbpHjvPVoaWU/OOhTg7bXk+yH6p+k1kG3ihKN5it1pQtqTQYT+ eartpOREmaS0zXApci87vNq9z/OzI5s5JqQbQXTC3aXy4WcvkNKHpPuMtMADlpImC2Nx G9KwYdvhHESZ8iA/s7yvXc4OFaaMZyP8m4UKQ90WXP6KBDe8XYdPpxsB9tENRvEBDpuy 6PXWMbFVaLlfZRpJZ43Qf8/59TKoQjP26oWpbPQLW5XLF+dEUwqZbn4JOGV/sKB9c5Dg LF7Q== X-Gm-Message-State: AO0yUKWSijLtgnS2S5/KIBkOSq9HLJxGL/t9AYSQUhMDsEWS1Djc9D3v Imbadj+L/NuJTPE0d6GC1HF3Gg== X-Google-Smtp-Source: AK7set+kviHpO/dgYo6fG95FwmeukrqggqusKN5eb8Q4daAsLpnqIvfLT8PSlOVWaMCGZUHBCi1JdQ== X-Received: by 2002:a5d:5183:0:b0:2bf:b5ec:4844 with SMTP id k3-20020a5d5183000000b002bfb5ec4844mr4689320wrv.19.1675811084196; Tue, 07 Feb 2023 15:04:44 -0800 (PST) Received: from usaari01.cust.communityfibre.co.uk ([2a02:6b6a:b566:0:c04f:2463:c151:8b87]) by smtp.gmail.com with ESMTPSA id j14-20020a05600c190e00b003dcc82ce53fsm146485wmq.38.2023.02.07.15.04.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Feb 2023 15:04:43 -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 v7 4/9] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() Date: Tue, 7 Feb 2023 23:04:31 +0000 Message-Id: <20230207230436.2690891-5-usama.arif@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230207230436.2690891-1-usama.arif@bytedance.com> References: <20230207230436.2690891-1-usama.arif@bytedance.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@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; } /*