From patchwork Sun Feb 26 11:07:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13152350 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 5B971C7EE2F for ; Sun, 26 Feb 2023 11:08:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229695AbjBZLIn (ORCPT ); Sun, 26 Feb 2023 06:08:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36022 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229644AbjBZLIi (ORCPT ); Sun, 26 Feb 2023 06:08:38 -0500 Received: from mail-wr1-x435.google.com (mail-wr1-x435.google.com [IPv6:2a00:1450:4864:20::435]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6BAF2E391 for ; Sun, 26 Feb 2023 03:08:10 -0800 (PST) Received: by mail-wr1-x435.google.com with SMTP id r7so3430348wrz.6 for ; Sun, 26 Feb 2023 03:08:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; 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=OivBWw2fC0XPAqVFrKNNGqM4Zo9U9YwXqHaW8wBeEGc=; b=VxCrwOsO5d51D+qxGU56U12/Bi1oSWb2V8N/WSXUn/RfWrQ6Ei6ewkTrmwmzWXtlEf 5PWKmXL//w+gNJ2lBwzUfLYDtc4Nljo6tLaTFo0UimNjQT0Agj4KY1YVu0iHm4b7uqM7 q2aS+BoZEGmMeqk7lq/8cDQvl6gJe3R/50HoLK9X79Ap54V0GqPfCvrJRVPrsg5N3e3v GzPn5YVhsu7Ox6p1K3jcqvLMPshqVmLucNu8EWcjGlK5lnyETbXiQtf0dp3EygPOIsRk YrwYlukZIIGQTeKCOhY9l0lf5gm5uvndbv58YwfVyOdobjwp/nkuyUZMli2uW6KQU1Nx uh/Q== 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=OivBWw2fC0XPAqVFrKNNGqM4Zo9U9YwXqHaW8wBeEGc=; b=Orky7rMia4yndWAYmJtfRvrUe95d3gZv7AgznojZ7ARehrbTv/dZquoiZpNH04tlMN 9QKCYMs+2LlOmQ5Pikd7O20si4NM3UrInMG87QminSMz97dXD7W3C4EK2zkW2ZZh60M1 Mhx94q7nnnS3nBxPSgGWzyY6kaB2P7KpsoIrfOsVRCQfAL3jiF/3Q0O3wjYx6GSL52mI PHtmoL4005/BAaj8GvrgIBBmAuGHzzv4rY+TteT/zgPSCxe+vJsMbrFWHBVl+nG/agWe jZvSyTkHJTyTXUUbde0tSkzcGt1rWY0YTggAZoH0oMvkLdH2gqkQuU+OeUAZznPGF1G2 kSbg== X-Gm-Message-State: AO0yUKV0RCoenHDn80jZ6I6uNblQSNfo+2m+LvviKrnUtknuPsm/6cal sPI7fcJ27RneIeRLfkNDgRPVrw== X-Google-Smtp-Source: AK7set+FTyurnhSGpCNcSuxWbPpEYuaf59S7DEc2Wp/E7rxmeIf77xGqg7zaTwWoSGONF3klerWcLQ== X-Received: by 2002:a5d:45c6:0:b0:2c7:aed:b981 with SMTP id b6-20020a5d45c6000000b002c70aedb981mr12298110wrs.30.1677409688797; Sun, 26 Feb 2023 03:08:08 -0800 (PST) Received: from usaari01.cust.communityfibre.co.uk ([2a02:6b6a:b566:0:df7b:4668:3e23:d0c9]) by smtp.gmail.com with ESMTPSA id v22-20020a1cf716000000b003e1fee8baacsm9157318wmh.25.2023.02.26.03.08.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 26 Feb 2023 03:08:08 -0800 (PST) From: Usama Arif To: dwmw2@infradead.org, tglx@linutronix.de, kim.phillips@amd.com, brgerst@gmail.com Cc: piotrgorski@cachyos.org, oleksandr@natalenko.name, 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 v12 04/11] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() Date: Sun, 26 Feb 2023 11:07:55 +0000 Message-Id: <20230226110802.103134-5-usama.arif@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230226110802.103134-1-usama.arif@bytedance.com> References: <20230226110802.103134-1-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. Signed-off-by: David Woodhouse Signed-off-by: Usama Arif Tested-by: Paul E. McKenney Tested-by: Kim Phillips Tested-by: Oleksandr Natalenko --- 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; } /*