From patchwork Sun Feb 26 11:07:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13152347 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 16DD6C64ED6 for ; Sun, 26 Feb 2023 11:08:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229516AbjBZLIO (ORCPT ); Sun, 26 Feb 2023 06:08:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35938 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229536AbjBZLIM (ORCPT ); Sun, 26 Feb 2023 06:08:12 -0500 Received: from mail-wm1-x32b.google.com (mail-wm1-x32b.google.com [IPv6:2a00:1450:4864:20::32b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6817D337 for ; Sun, 26 Feb 2023 03:08:07 -0800 (PST) Received: by mail-wm1-x32b.google.com with SMTP id r19-20020a05600c459300b003eb3e2a5e7bso543182wmo.0 for ; Sun, 26 Feb 2023 03:08:07 -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=8SFcyAg12RLJRTJdp4mtixGxiIqYpnMS3znV8hvpPts=; b=hI78QYpmhKZwO4mzxF/UimiezGc+2wFxUxNXZcbhVXrN9v/kQruAnueLLprhAIc2+g rPhZDr3ZD/ZkWIyLwkdY8ngMUMXEpbK8u3uCNalhHOSIeSov/5w2tH7+1z19audJ4EGB DdSi1lgBp+q/uyAquDfAiknnRnWqPZAUdewkZ1MRaB0wFkZOu9/FCVfsS+N1mMJzCVMv 2eRjeK5kNtUy3xUIHAO0qr5aujHcDbor/Jj2leiS6m3k0sk0xrTmdUCDEuZH/PvjxLQu tRg/bXyDdTS72ALHi4dov5j801ALNrAbnquooCspjLIlrOru1+a1Cl76vYYIirJjvXHC y4vQ== 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=8SFcyAg12RLJRTJdp4mtixGxiIqYpnMS3znV8hvpPts=; b=ugMaVdlgO+cypLjrgIWrx1N2T4ve/V76umCgYnI/i8wBwCdpvywWcL//ZTPD8b6l8R 1chS5WODo6ayCBIKxVsQ9DxAtZktuqSKf90D/y5uqTUVEbBOAKBFu7T1RlveLxEx91t0 LExywUIA0Yf8FZyulpfT2Wt47Y6k9cJ7OuywK0LfUbmmRVwFiokQ7G+/VxqbGOjOZbuE EkFkVHn0im9cIgN7JgAHlNmXFkGCd0PXfVYadQqEEp5Rv9TGH4Brmo03VuPJ4t85RduE g2qHW0P8cg/UGXCxUlRaxM6ntvo5DkyN654diy/hwZdm8wIcYNVrA4rgWON/VPebkKJZ jAUQ== X-Gm-Message-State: AO0yUKUOgBQuG35QlDufT2q1pyQUOkZE8iCa8+Rv8RdAMP9tLUTvq6vN lAaNuGV4XObCMSL9HdjzKPdGlA== X-Google-Smtp-Source: AK7set/LY/smYP6Xt8GC2+xB49frpFQfsGIj1taJE3tW1pIsoPs+q6wG3SkBE9YCU6gJHv+g3wJ3Ug== X-Received: by 2002:a05:600c:3b1e:b0:3ea:e5fc:a5a4 with SMTP id m30-20020a05600c3b1e00b003eae5fca5a4mr7617365wms.1.1677409685966; Sun, 26 Feb 2023 03:08:05 -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.25.2023.02.26.03.08.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 26 Feb 2023 03:08:05 -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 01/11] x86/apic/x2apic: Allow CPU cluster_mask to be populated in parallel Date: Sun, 26 Feb 2023 11:07:52 +0000 Message-Id: <20230226110802.103134-2-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 Each of the sibling CPUs in a cluster uses the same clustermask. The first CPU in a cluster will need a new clustermask allocated, while subsequent siblings will use the same clustermask as the first. However, the CPU being brought up cannot yet perform memory allocations at the point that this occurs in init_x2apic_ldr(). So at present, the alloc_clustermask() function allocates a clustermask just in case it's needed, storing it in the global cluster_hotplug_mask. A CPU which is the first sibling of a cluster will "take" it from there and set cluster_hotplug_mask to NULL, in order for alloc_clustermask() to allocate a new one before bringing up the next CPU. To facilitate parallel bringup of CPUs in future, switch to a model where alloc_clustermask() prepopulates the clustermask in the per_cpu data for each present CPU in the cluster in advance. All that the CPU needs to do for itself in init_x2apic_ldr() is set its own bit in that mask. The 'node' and 'clusterid' members of struct cluster_mask are thus redundant, and it can become a simple struct cpumask instead. Suggested-by: Thomas Gleixner 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/apic/x2apic_cluster.c | 126 +++++++++++++++++--------- 1 file changed, 82 insertions(+), 44 deletions(-) diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c index e696e22d0531..b2b2b7f3e03f 100644 --- a/arch/x86/kernel/apic/x2apic_cluster.c +++ b/arch/x86/kernel/apic/x2apic_cluster.c @@ -9,11 +9,7 @@ #include "local.h" -struct cluster_mask { - unsigned int clusterid; - int node; - struct cpumask mask; -}; +#define apic_cluster(apicid) ((apicid) >> 4) /* * __x2apic_send_IPI_mask() possibly needs to read @@ -23,8 +19,7 @@ struct cluster_mask { static u32 *x86_cpu_to_logical_apicid __read_mostly; static DEFINE_PER_CPU(cpumask_var_t, ipi_mask); -static DEFINE_PER_CPU_READ_MOSTLY(struct cluster_mask *, cluster_masks); -static struct cluster_mask *cluster_hotplug_mask; +static DEFINE_PER_CPU_READ_MOSTLY(struct cpumask *, cluster_masks); static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id) { @@ -60,10 +55,10 @@ __x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest) /* Collapse cpus in a cluster so a single IPI per cluster is sent */ for_each_cpu(cpu, tmpmsk) { - struct cluster_mask *cmsk = per_cpu(cluster_masks, cpu); + struct cpumask *cmsk = per_cpu(cluster_masks, cpu); dest = 0; - for_each_cpu_and(clustercpu, tmpmsk, &cmsk->mask) + for_each_cpu_and(clustercpu, tmpmsk, cmsk) dest |= x86_cpu_to_logical_apicid[clustercpu]; if (!dest) @@ -71,7 +66,7 @@ __x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest) __x2apic_send_IPI_dest(dest, vector, APIC_DEST_LOGICAL); /* Remove cluster CPUs from tmpmask */ - cpumask_andnot(tmpmsk, tmpmsk, &cmsk->mask); + cpumask_andnot(tmpmsk, tmpmsk, cmsk); } local_irq_restore(flags); @@ -105,55 +100,98 @@ static u32 x2apic_calc_apicid(unsigned int cpu) static void init_x2apic_ldr(void) { - struct cluster_mask *cmsk = this_cpu_read(cluster_masks); - u32 cluster, apicid = apic_read(APIC_LDR); - unsigned int cpu; + struct cpumask *cmsk = this_cpu_read(cluster_masks); - x86_cpu_to_logical_apicid[smp_processor_id()] = apicid; + BUG_ON(!cmsk); - if (cmsk) - goto update; - - cluster = apicid >> 16; - for_each_online_cpu(cpu) { - cmsk = per_cpu(cluster_masks, cpu); - /* Matching cluster found. Link and update it. */ - if (cmsk && cmsk->clusterid == cluster) - goto update; + cpumask_set_cpu(smp_processor_id(), cmsk); +} + +/* + * As an optimisation during boot, set the cluster_mask for all present + * CPUs at once, to prevent each of them having to iterate over the others + * to find the existing cluster_mask. + */ +static void prefill_clustermask(struct cpumask *cmsk, unsigned int cpu, u32 cluster) +{ + int cpu_i; + + for_each_present_cpu(cpu_i) { + struct cpumask **cpu_cmsk = &per_cpu(cluster_masks, cpu_i); + u32 apicid = apic->cpu_present_to_apicid(cpu_i); + + if (apicid == BAD_APICID || cpu_i == cpu || apic_cluster(apicid) != cluster) + continue; + + if (WARN_ON_ONCE(*cpu_cmsk == cmsk)) + continue; + + BUG_ON(*cpu_cmsk); + *cpu_cmsk = cmsk; } - cmsk = cluster_hotplug_mask; - cmsk->clusterid = cluster; - cluster_hotplug_mask = NULL; -update: - this_cpu_write(cluster_masks, cmsk); - cpumask_set_cpu(smp_processor_id(), &cmsk->mask); } -static int alloc_clustermask(unsigned int cpu, int node) +static int alloc_clustermask(unsigned int cpu, u32 cluster, int node) { + struct cpumask *cmsk = NULL; + unsigned int cpu_i; + + /* + * At boot time, the CPU present mask is stable. The cluster mask is + * allocated for the first CPU in the cluster and propagated to all + * present siblings in the cluster. If the cluster mask is already set + * on entry to this function for a given CPU, there is nothing to do. + */ if (per_cpu(cluster_masks, cpu)) return 0; + + if (system_state < SYSTEM_RUNNING) + goto alloc; + /* - * If a hotplug spare mask exists, check whether it's on the right - * node. If not, free it and allocate a new one. + * On post boot hotplug for a CPU which was not present at boot time, + * iterate over all possible CPUs (even those which are not present + * any more) to find any existing cluster mask. */ - if (cluster_hotplug_mask) { - if (cluster_hotplug_mask->node == node) - return 0; - kfree(cluster_hotplug_mask); + for_each_possible_cpu(cpu_i) { + u32 apicid = apic->cpu_present_to_apicid(cpu_i); + + if (apicid != BAD_APICID && apic_cluster(apicid) == cluster) { + cmsk = per_cpu(cluster_masks, cpu_i); + /* + * If the cluster is already initialized, just store + * the mask and return. There's no need to propagate. + */ + if (cmsk) { + per_cpu(cluster_masks, cpu) = cmsk; + return 0; + } + } } - - cluster_hotplug_mask = kzalloc_node(sizeof(*cluster_hotplug_mask), - GFP_KERNEL, node); - if (!cluster_hotplug_mask) + /* + * No CPU in the cluster has ever been initialized, so fall through to + * the boot time code which will also populate the cluster mask for any + * other CPU in the cluster which is (now) present. + */ +alloc: + cmsk = kzalloc_node(sizeof(*cmsk), GFP_KERNEL, node); + if (!cmsk) return -ENOMEM; - cluster_hotplug_mask->node = node; + per_cpu(cluster_masks, cpu) = cmsk; + prefill_clustermask(cmsk, cpu, cluster); + return 0; } static int x2apic_prepare_cpu(unsigned int cpu) { - if (alloc_clustermask(cpu, cpu_to_node(cpu)) < 0) + u32 phys_apicid = apic->cpu_present_to_apicid(cpu); + u32 cluster = apic_cluster(phys_apicid); + u32 logical_apicid = (cluster << 16) | (1 << (phys_apicid & 0xf)); + + x86_cpu_to_logical_apicid[cpu] = logical_apicid; + + if (alloc_clustermask(cpu, cluster, cpu_to_node(cpu)) < 0) return -ENOMEM; if (!zalloc_cpumask_var(&per_cpu(ipi_mask, cpu), GFP_KERNEL)) return -ENOMEM; @@ -162,10 +200,10 @@ static int x2apic_prepare_cpu(unsigned int cpu) static int x2apic_dead_cpu(unsigned int dead_cpu) { - struct cluster_mask *cmsk = per_cpu(cluster_masks, dead_cpu); + struct cpumask *cmsk = per_cpu(cluster_masks, dead_cpu); if (cmsk) - cpumask_clear_cpu(dead_cpu, &cmsk->mask); + cpumask_clear_cpu(dead_cpu, cmsk); free_cpumask_var(per_cpu(ipi_mask, dead_cpu)); return 0; } From patchwork Sun Feb 26 11:07:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13152349 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 C24BDC7EE2D for ; Sun, 26 Feb 2023 11:08:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229673AbjBZLIk (ORCPT ); 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Sun, 26 Feb 2023 03:08:06 -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 02/11] cpu/hotplug: Move idle_thread_get() to Date: Sun, 26 Feb 2023 11:07:53 +0000 Message-Id: <20230226110802.103134-3-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 Instead of relying purely on the special-case wrapper in bringup_cpu() to pass the idle thread to __cpu_up(), expose idle_thread_get() so that the architecture code can obtain it directly when necessary. This will be useful when the existing __cpu_up() is split into multiple phases, only *one* of which will actually need the idle thread. If the architecture code is to register its new pre-bringup states with the cpuhp core, having a special-case wrapper to pass extra arguments is non-trivial and it's easier just to let the arch register its function pointer to be invoked with the standard API. Signed-off-by: David Woodhouse Reviewed-by: Thomas Gleixner Signed-off-by: Usama Arif Tested-by: Paul E. McKenney Tested-by: Kim Phillips Tested-by: Oleksandr Natalenko --- include/linux/smpboot.h | 7 +++++++ kernel/smpboot.h | 2 -- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/include/linux/smpboot.h b/include/linux/smpboot.h index 9d1bc65d226c..3862addcaa34 100644 --- a/include/linux/smpboot.h +++ b/include/linux/smpboot.h @@ -5,6 +5,13 @@ #include struct task_struct; + +#ifdef CONFIG_GENERIC_SMP_IDLE_THREAD +struct task_struct *idle_thread_get(unsigned int cpu); +#else +static inline struct task_struct *idle_thread_get(unsigned int cpu) { return NULL; } +#endif + /* Cookie handed to the thread_fn*/ struct smpboot_thread_data; diff --git a/kernel/smpboot.h b/kernel/smpboot.h index 34dd3d7ba40b..60c609318ad6 100644 --- a/kernel/smpboot.h +++ b/kernel/smpboot.h @@ -5,11 +5,9 @@ struct task_struct; #ifdef CONFIG_GENERIC_SMP_IDLE_THREAD -struct task_struct *idle_thread_get(unsigned int cpu); void idle_thread_set_boot_cpu(void); void idle_threads_init(void); #else -static inline struct task_struct *idle_thread_get(unsigned int cpu) { return NULL; } static inline void idle_thread_set_boot_cpu(void) { } static inline void idle_threads_init(void) { } #endif From patchwork Sun Feb 26 11:07:54 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13152352 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 AC143C7EE33 for ; Sun, 26 Feb 2023 11:08:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229647AbjBZLIo (ORCPT ); Sun, 26 Feb 2023 06:08:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229661AbjBZLIj (ORCPT ); Sun, 26 Feb 2023 06:08:39 -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 AF134D521 for ; 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Sun, 26 Feb 2023 03:08:07 -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 03/11] cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU Date: Sun, 26 Feb 2023 11:07:54 +0000 Message-Id: <20230226110802.103134-4-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 There is often significant latency in the early stages of CPU bringup, and time is wasted by waking each CPU (e.g. with SIPI/INIT/INIT on x86) and then waiting for it to respond before moving on to the next. Allow a platform to register a set of pre-bringup CPUHP states to which each CPU can be stepped in parallel, thus absorbing some of that latency. There is a subtlety here: even with an empty CPUHP_BP_PARALLEL_DYN step, this means that *all* CPUs are brought through the prepare states and to CPUHP_BP_PREPARE_DYN before any of them are taken to CPUHP_BRINGUP_CPU and then are allowed to run for themselves to CPUHP_ONLINE. So any combination of prepare/start calls which depend on A-B ordering for each CPU in turn, such as the X2APIC code which used to allocate a cluster mask 'just in case' and store it in a global variable in the prep stage, then potentially consume that preallocated structure from the AP and set the global pointer to NULL to be reallocated in CPUHP_X2APIC_PREPARE for the next CPU... would explode horribly. Any platform enabling the CPUHP_BP_PARALLEL_DYN steps must be reviewed and tested to ensure that such issues do not exist, and the existing behaviour of bringing CPUs to CPUHP_BP_PREPARE_DYN and then immediately to CPUHP_BRINGUP_CPU and CPUHP_ONLINE only one at a time does not change unless such a state is registered. Note that the new parallel stages do *not* yet bring each AP to the CPUHP_BRINGUP_CPU state at the same time, only to the new states which exist before it. The final loop in bringup_nonboot_cpus() is untouched, bringing each AP in turn from the final PARALLEL_DYN state (or all the way from CPUHP_OFFLINE) to CPUHP_BRINGUP_CPU and then waiting for that AP to do its own processing and reach CPUHP_ONLINE before releasing the next. Parallelising that part by bringing them all to CPUHP_BRINGUP_CPU and then waiting for them all is an exercise for the future. Signed-off-by: David Woodhouse Signed-off-by: Usama Arif Tested-by: Paul E. McKenney Tested-by: Kim Phillips Tested-by: Oleksandr Natalenko --- include/linux/cpuhotplug.h | 2 ++ kernel/cpu.c | 31 +++++++++++++++++++++++++++++-- 2 files changed, 31 insertions(+), 2 deletions(-) diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 6c6859bfc454..e5a73ae6ccc0 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -133,6 +133,8 @@ enum cpuhp_state { CPUHP_MIPS_SOC_PREPARE, CPUHP_BP_PREPARE_DYN, CPUHP_BP_PREPARE_DYN_END = CPUHP_BP_PREPARE_DYN + 20, + CPUHP_BP_PARALLEL_DYN, + CPUHP_BP_PARALLEL_DYN_END = CPUHP_BP_PARALLEL_DYN + 4, CPUHP_BRINGUP_CPU, /* diff --git a/kernel/cpu.c b/kernel/cpu.c index 6c0a92ca6bb5..fffb0da61ccc 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1504,8 +1504,30 @@ int bringup_hibernate_cpu(unsigned int sleep_cpu) void bringup_nonboot_cpus(unsigned int setup_max_cpus) { + unsigned int n = setup_max_cpus - num_online_cpus(); unsigned int cpu; + /* + * An architecture may have registered parallel pre-bringup states to + * which each CPU may be brought in parallel. For each such state, + * bring N CPUs to it in turn before the final round of bringing them + * online. + */ + if (n > 0) { + enum cpuhp_state st = CPUHP_BP_PARALLEL_DYN; + + while (st <= CPUHP_BP_PARALLEL_DYN_END && cpuhp_hp_states[st].name) { + int i = n; + + for_each_present_cpu(cpu) { + cpu_up(cpu, st); + if (!--i) + break; + } + st++; + } + } + for_each_present_cpu(cpu) { if (num_online_cpus() >= setup_max_cpus) break; @@ -1882,6 +1904,10 @@ static int cpuhp_reserve_state(enum cpuhp_state state) step = cpuhp_hp_states + CPUHP_BP_PREPARE_DYN; end = CPUHP_BP_PREPARE_DYN_END; break; + case CPUHP_BP_PARALLEL_DYN: + step = cpuhp_hp_states + CPUHP_BP_PARALLEL_DYN; + end = CPUHP_BP_PARALLEL_DYN_END; + break; default: return -EINVAL; } @@ -1906,14 +1932,15 @@ static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name, /* * If name is NULL, then the state gets removed. * - * CPUHP_AP_ONLINE_DYN and CPUHP_BP_PREPARE_DYN are handed out on + * CPUHP_AP_ONLINE_DYN and CPUHP_BP_P*_DYN are handed out on * the first allocation from these dynamic ranges, so the removal * would trigger a new allocation and clear the wrong (already * empty) state, leaving the callbacks of the to be cleared state * dangling, which causes wreckage on the next hotplug operation. */ if (name && (state == CPUHP_AP_ONLINE_DYN || - state == CPUHP_BP_PREPARE_DYN)) { + state == CPUHP_BP_PREPARE_DYN || + state == CPUHP_BP_PARALLEL_DYN)) { ret = cpuhp_reserve_state(state); if (ret < 0) return ret; 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 ; 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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; } /* From patchwork Sun Feb 26 11:07:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13152348 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 8AD7AC7EE32 for ; Sun, 26 Feb 2023 11:08:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229556AbjBZLIQ (ORCPT ); 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Sun, 26 Feb 2023 03:08:09 -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 05/11] x86/smpboot: Split up native_cpu_up into separate phases and document them Date: Sun, 26 Feb 2023 11:07:56 +0000 Message-Id: <20230226110802.103134-6-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 There are four logical parts to what native_cpu_up() does on the BSP (or on the controlling CPU for a later hotplug): 1) Wake the AP by sending the INIT/SIPI/SIPI sequence. 2) Wait for the AP to make it as far as wait_for_master_cpu() which sets that CPU's bit in cpu_initialized_mask, then sets the bit in cpu_callout_mask to let the AP proceed through cpu_init(). 3) Wait for the AP to finish cpu_init() and get as far as the smp_callin() call, which sets that CPU's bit in cpu_callin_mask. 4) Perform the TSC synchronization and wait for the AP to actually mark itself online in cpu_online_mask. In preparation to allow these phases to operate in parallel on multiple APs, split them out into separate functions and document the interactions a little more clearly in both the BSP and AP code paths. No functional change intended. 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 | 181 ++++++++++++++++++++++++++------------ 1 file changed, 127 insertions(+), 54 deletions(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 3a793772a2aa..b18c1385e181 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -204,6 +204,10 @@ static void smp_callin(void) wmb(); + /* + * This runs the AP through all the cpuhp states to its target + * state (CPUHP_ONLINE in the case of serial bringup). + */ notify_cpu_starting(cpuid); /* @@ -231,17 +235,32 @@ static void notrace start_secondary(void *unused) load_cr3(swapper_pg_dir); __flush_tlb_all(); #endif + /* + * Sync point with do_wait_cpu_initialized(). Before proceeding through + * cpu_init(), the AP will call wait_for_master_cpu() which sets its + * own bit in cpu_initialized_mask and then waits for the BSP to set + * its bit in cpu_callout_mask to release it. + */ cpu_init_secondary(); rcu_cpu_starting(raw_smp_processor_id()); x86_cpuinit.early_percpu_clock_init(); + + /* + * Sync point with do_wait_cpu_callin(). The AP doesn't wait here + * but just sets the bit to let the controlling CPU (BSP) know that + * it's got this far. + */ smp_callin(); enable_start_cpu0 = 0; /* otherwise gcc will move up smp_processor_id before the cpu_init */ barrier(); + /* - * Check TSC synchronization with the boot CPU: + * Check TSC synchronization with the boot CPU (or whichever CPU + * is controlling the bringup). It will do its part of this from + * do_wait_cpu_online(), making it an implicit sync point. */ check_tsc_sync_target(); @@ -254,6 +273,7 @@ static void notrace start_secondary(void *unused) * half valid vector space. */ lock_vector_lock(); + /* Sync point with do_wait_cpu_online() */ set_cpu_online(smp_processor_id(), true); lapic_online(); unlock_vector_lock(); @@ -1083,7 +1103,6 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle, unsigned long start_ip = real_mode_header->trampoline_start; unsigned long boot_error = 0; - unsigned long timeout; #ifdef CONFIG_X86_64 /* If 64-bit wakeup method exists, use the 64-bit mode trampoline IP */ @@ -1144,55 +1163,94 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle, boot_error = wakeup_cpu_via_init_nmi(cpu, start_ip, apicid, cpu0_nmi_registered); - if (!boot_error) { - /* - * Wait 10s total for first sign of life from AP - */ - boot_error = -1; - timeout = jiffies + 10*HZ; - while (time_before(jiffies, timeout)) { - if (cpumask_test_cpu(cpu, cpu_initialized_mask)) { - /* - * Tell AP to proceed with initialization - */ - cpumask_set_cpu(cpu, cpu_callout_mask); - boot_error = 0; - break; - } - schedule(); - } - } + return boot_error; +} - if (!boot_error) { - /* - * Wait till AP completes initial initialization - */ - while (!cpumask_test_cpu(cpu, cpu_callin_mask)) { - /* - * Allow other tasks to run while we wait for the - * AP to come online. This also gives a chance - * for the MTRR work(triggered by the AP coming online) - * to be completed in the stop machine context. - */ - schedule(); - } +static int do_wait_cpu_cpumask(unsigned int cpu, const struct cpumask *mask) +{ + unsigned long timeout; + + /* + * Wait up to 10s for the CPU to report in. + */ + timeout = jiffies + 10*HZ; + while (time_before(jiffies, timeout)) { + if (cpumask_test_cpu(cpu, mask)) + return 0; + + schedule(); } + return -1; +} - if (x86_platform.legacy.warm_reset) { - /* - * Cleanup possible dangling ends... - */ - smpboot_restore_warm_reset_vector(); +/* + * Bringup step two: Wait for the target AP to reach cpu_init_secondary() + * and thus wait_for_master_cpu(), then set cpu_callout_mask to allow it + * to proceed. The AP will then proceed past setting its 'callin' bit + * and end up waiting in check_tsc_sync_target() until we reach + * do_wait_cpu_online() to tend to it. + */ +static int do_wait_cpu_initialized(unsigned int cpu) +{ + /* + * Wait for first sign of life from AP. + */ + if (do_wait_cpu_cpumask(cpu, cpu_initialized_mask)) + return -1; + + cpumask_set_cpu(cpu, cpu_callout_mask); + return 0; +} + +/* + * Bringup step three: Wait for the target AP to reach smp_callin(). + * The AP is not waiting for us here so we don't need to parallelise + * this step. Not entirely clear why we care about this, since we just + * proceed directly to TSC synchronization which is the next sync + * point with the AP anyway. + */ +static int do_wait_cpu_callin(unsigned int cpu) +{ + /* + * Wait till AP completes initial initialization. + */ + return do_wait_cpu_cpumask(cpu, cpu_callin_mask); +} + +/* + * Bringup step four: Synchronize the TSC and wait for the target AP + * to reach set_cpu_online() in start_secondary(). + */ +static int do_wait_cpu_online(unsigned int cpu) +{ + unsigned long flags; + + /* + * Check TSC synchronization with the AP (keep irqs disabled + * while doing so): + */ + local_irq_save(flags); + check_tsc_sync_source(cpu); + local_irq_restore(flags); + + /* + * Wait for the AP to mark itself online. Not entirely + * clear why we care, since the generic cpuhp code will + * wait for it to each CPUHP_AP_ONLINE_IDLE before going + * ahead with the rest of the bringup anyway. + */ + while (!cpu_online(cpu)) { + cpu_relax(); + touch_nmi_watchdog(); } - return boot_error; + return 0; } -int native_cpu_up(unsigned int cpu, struct task_struct *tidle) +static int do_cpu_up(unsigned int cpu, struct task_struct *tidle) { int apicid = apic->cpu_present_to_apicid(cpu); int cpu0_nmi_registered = 0; - unsigned long flags; int err, ret = 0; lockdep_assert_irqs_enabled(); @@ -1239,19 +1297,6 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle) goto unreg_nmi; } - /* - * Check TSC synchronization with the AP (keep irqs disabled - * while doing so): - */ - local_irq_save(flags); - check_tsc_sync_source(cpu); - local_irq_restore(flags); - - while (!cpu_online(cpu)) { - cpu_relax(); - touch_nmi_watchdog(); - } - unreg_nmi: /* * Clean up the nmi handler. Do this after the callin and callout sync @@ -1263,6 +1308,34 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle) return ret; } +int native_cpu_up(unsigned int cpu, struct task_struct *tidle) +{ + int ret; + + ret = do_cpu_up(cpu, tidle); + if (ret) + return ret; + + ret = do_wait_cpu_initialized(cpu); + if (ret) + return ret; + + ret = do_wait_cpu_callin(cpu); + if (ret) + return ret; + + ret = do_wait_cpu_online(cpu); + + if (x86_platform.legacy.warm_reset) { + /* + * Cleanup possible dangling ends... + */ + smpboot_restore_warm_reset_vector(); + } + + return ret; +} + /** * arch_disable_smp_support() - disables SMP support for x86 at runtime */ From patchwork Sun Feb 26 11:07:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13152362 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 E53D7C6FA8E for ; Sun, 26 Feb 2023 11:08:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229762AbjBZLI7 (ORCPT ); Sun, 26 Feb 2023 06:08:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36062 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229688AbjBZLIl (ORCPT ); Sun, 26 Feb 2023 06:08:41 -0500 Received: from mail-wm1-x332.google.com (mail-wm1-x332.google.com [IPv6:2a00:1450:4864:20::332]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 075E0D326 for ; Sun, 26 Feb 2023 03:08:12 -0800 (PST) Received: by mail-wm1-x332.google.com with SMTP id j19-20020a05600c191300b003eb3e1eb0caso618854wmq.1 for ; Sun, 26 Feb 2023 03:08:11 -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=o/vcGB3tRiPqgIjGstr77HWq6H41b6Xz6eyjpGifXDM=; b=C3SqKIThhTfaMRirw+2QelUYjbwo9roa+7rXabxBaMR7RmAMK7OOh+HPfPvyuKktfP AXVauvuRgbNfibMHLPZ8BiuNnE6APMiMWUhZuHMya4ztY4vR63hnsF+twu6QZYw1lwfV MTJgF6KXtwKl0fg1OvZGtvZQcIeNaFAegMzZp/f2TolsAxwx2UnX5BPTWN3ZNQebZfnh 7zln4a5UXunWlVs10HjwK0MfYcQ4e5ma6wF/cYmtj+PaWV9UsHcT75T9M4jY7jgib94x m0qnVaAmqHb1Oyep/vcRptVrzUinPU92cGHsH8zaZR2L16lgcoaq9BgTE+3P4+j4e0Dk N/tw== 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=o/vcGB3tRiPqgIjGstr77HWq6H41b6Xz6eyjpGifXDM=; b=CASC3BT3II+ViSgPJU+riu5F6mdbKi65VoIj3ZptOKbA1IAiRqUb8PPx+dYs84lsbm kURp7EUePBsxL7cimeEfjdpL9jv7bDi54BERz8sUqHueK0gyW9nfBvnUD5Gn3TPL8F/7 kFjT5gYFcHWzy6nepAn758temGpG9qbWhxBiUe9n4/JOkqHjCmcc6xSidsWlqZkDSfnY eaC7pdiriJ21ZW9k+ePSnlt9eLR85+AcoM8CPsOHY4eCkYSA7ob9nIH4U0VVI+YceQIB zggmC6E2TDWIDYTM39LLVFeBbe4x5ofNfooS4H9S1yJFSAx9cV2cTTHWqUbs6J31zshI 1dkg== X-Gm-Message-State: AO0yUKVDU5LNgQ5ISiGda9S8sV1SWyCQPtqrz+OpxXcZA7twW3ovriXQ 8AagDDI58FOmHvEQvPZVeU9aQQ== X-Google-Smtp-Source: AK7set9mL8Niyd0GcyAD80gTw0dOANgXeCK88Szy7Y9FMs2NS9e/IcJVyYZXlOxdJM8d3LUJSSX40A== X-Received: by 2002:a05:600c:3c91:b0:3eb:36fa:b78d with SMTP id bg17-20020a05600c3c9100b003eb36fab78dmr2533431wmb.23.1677409690383; Sun, 26 Feb 2023 03:08:10 -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.25.2023.02.26.03.08.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 26 Feb 2023 03:08:10 -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 06/11] x86/smpboot: Remove initial_stack on 64-bit Date: Sun, 26 Feb 2023 11:07:57 +0000 Message-Id: <20230226110802.103134-7-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: Brian Gerst Eliminating global variables from the CPU startup path in order to simplify it and facilitate parallel startup. Remove initial_stack, and load RSP from current_task->thread.sp instead. Signed-off-by: Brian Gerst Reviewed-by: David Woodhouse Signed-off-by: David Woodhouse Tested-by: Usama Arif Signed-off-by: Usama Arif Signed-off-by: Brian Gerst Reviewed-by: David Woodhouse Signed-off-by: David Woodhouse Tested-by: Usama Arif Signed-off-by: Usama Arif Tested-by: Guilherme G. Piccoli Signed-off-by: Brian Gerst Reviewed-by: David Woodhouse Signed-off-by: David Woodhouse Tested-by: Usama Arif Signed-off-by: Usama Arif Tested-by: Guilherme G. Piccoli --- arch/x86/include/asm/processor.h | 6 ++++- arch/x86/include/asm/smp.h | 5 +++- arch/x86/kernel/acpi/sleep.c | 5 ++-- arch/x86/kernel/asm-offsets.c | 1 + arch/x86/kernel/head_64.S | 43 +++++++++++++++++++++----------- arch/x86/kernel/smpboot.c | 7 +++++- arch/x86/xen/xen-head.S | 2 +- 7 files changed, 48 insertions(+), 21 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 4e35c66edeb7..bdde7316e75b 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -648,7 +648,11 @@ static inline void spin_lock_prefetch(const void *x) #define KSTK_ESP(task) (task_pt_regs(task)->sp) #else -#define INIT_THREAD { } +extern unsigned long __end_init_task[]; + +#define INIT_THREAD { \ + .sp = (unsigned long)&__end_init_task - sizeof(struct pt_regs), \ +} extern unsigned long KSTK_ESP(struct task_struct *task); diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h index b4dbb20dab1a..bf2c51df9e0b 100644 --- a/arch/x86/include/asm/smp.h +++ b/arch/x86/include/asm/smp.h @@ -199,5 +199,8 @@ extern void nmi_selftest(void); #define nmi_selftest() do { } while (0) #endif -#endif /* __ASSEMBLY__ */ +extern unsigned int smpboot_control; + +#endif /* !__ASSEMBLY__ */ + #endif /* _ASM_X86_SMP_H */ diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c index 3b7f4cdbf2e0..ab6e29b32c04 100644 --- a/arch/x86/kernel/acpi/sleep.c +++ b/arch/x86/kernel/acpi/sleep.c @@ -111,13 +111,14 @@ int x86_acpi_suspend_lowlevel(void) saved_magic = 0x12345678; #else /* CONFIG_64BIT */ #ifdef CONFIG_SMP - initial_stack = (unsigned long)temp_stack + sizeof(temp_stack); + current->thread.sp = (unsigned long)temp_stack + sizeof(temp_stack); early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(smp_processor_id()); initial_gs = per_cpu_offset(smp_processor_id()); + smpboot_control = smp_processor_id(); #endif initial_code = (unsigned long)wakeup_long64; - saved_magic = 0x123456789abcdef0L; + saved_magic = 0x123456789abcdef0L; #endif /* CONFIG_64BIT */ /* diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index 82c783da16a8..797ae1a15c91 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -108,6 +108,7 @@ static void __used common(void) OFFSET(TSS_sp1, tss_struct, x86_tss.sp1); OFFSET(TSS_sp2, tss_struct, x86_tss.sp2); OFFSET(X86_top_of_stack, pcpu_hot, top_of_stack); + OFFSET(X86_current_task, pcpu_hot, current_task); #ifdef CONFIG_CALL_DEPTH_TRACKING OFFSET(X86_call_depth, pcpu_hot, call_depth); #endif diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 222efd4a09bc..5a2417d788d1 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -61,8 +61,8 @@ SYM_CODE_START_NOALIGN(startup_64) * tables and then reload them. */ - /* Set up the stack for verify_cpu(), similar to initial_stack below */ - leaq (__end_init_task - FRAME_SIZE)(%rip), %rsp + /* Set up the stack for verify_cpu() */ + leaq (__end_init_task - PTREGS_SIZE)(%rip), %rsp leaq _text(%rip), %rdi @@ -241,6 +241,24 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) UNWIND_HINT_EMPTY ANNOTATE_NOENDBR // above +#ifdef CONFIG_SMP + movl smpboot_control(%rip), %ecx + + /* Get the per cpu offset for the given CPU# which is in ECX */ + movq __per_cpu_offset(,%rcx,8), %rdx +#else + xorl %edx, %edx +#endif /* CONFIG_SMP */ + + /* + * Setup a boot time stack - Any secondary CPU will have lost its stack + * by now because the cr3-switch above unmaps the real-mode stack. + * + * RDX contains the per-cpu offset + */ + movq pcpu_hot + X86_current_task(%rdx), %rax + movq TASK_threadsp(%rax), %rsp + /* * We must switch to a new descriptor in kernel space for the GDT * because soon the kernel won't have access anymore to the userspace @@ -275,12 +293,6 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) movl initial_gs+4(%rip),%edx wrmsr - /* - * Setup a boot time stack - Any secondary CPU will have lost its stack - * by now because the cr3-switch above unmaps the real-mode stack - */ - movq initial_stack(%rip), %rsp - /* Setup and Load IDT */ pushq %rsi call early_setup_idt @@ -372,7 +384,11 @@ SYM_CODE_END(secondary_startup_64) SYM_CODE_START(start_cpu0) ANNOTATE_NOENDBR UNWIND_HINT_EMPTY - movq initial_stack(%rip), %rsp + + /* Find the idle task stack */ + movq PER_CPU_VAR(pcpu_hot) + X86_current_task, %rcx + movq TASK_threadsp(%rcx), %rsp + jmp .Ljump_to_C_code SYM_CODE_END(start_cpu0) #endif @@ -420,12 +436,6 @@ SYM_DATA(initial_gs, .quad INIT_PER_CPU_VAR(fixed_percpu_data)) #ifdef CONFIG_AMD_MEM_ENCRYPT SYM_DATA(initial_vc_handler, .quad handle_vc_boot_ghcb) #endif - -/* - * The FRAME_SIZE gap is a convention which helps the in-kernel unwinder - * reliably detect the end of the stack. - */ -SYM_DATA(initial_stack, .quad init_thread_union + THREAD_SIZE - FRAME_SIZE) __FINITDATA __INIT @@ -660,6 +670,9 @@ SYM_DATA_END(level1_fixmap_pgt) SYM_DATA(early_gdt_descr, .word GDT_ENTRIES*8-1) SYM_DATA_LOCAL(early_gdt_descr_base, .quad INIT_PER_CPU_VAR(gdt_page)) + .align 16 +SYM_DATA(smpboot_control, .long 0) + .align 16 /* This must match the first entry in level2_kernel_pgt */ SYM_DATA(phys_base, .quad 0x0) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index b18c1385e181..62e3bf37f0b8 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1112,7 +1112,12 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle, idle->thread.sp = (unsigned long)task_pt_regs(idle); early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(cpu); initial_code = (unsigned long)start_secondary; - initial_stack = idle->thread.sp; + + if (IS_ENABLED(CONFIG_X86_32)) { + initial_stack = idle->thread.sp; + } else { + smpboot_control = cpu; + } /* Enable the espfix hack for this CPU */ init_espfix_ap(cpu); diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S index ffaa62167f6e..6bd391476656 100644 --- a/arch/x86/xen/xen-head.S +++ b/arch/x86/xen/xen-head.S @@ -49,7 +49,7 @@ SYM_CODE_START(startup_xen) ANNOTATE_NOENDBR cld - mov initial_stack(%rip), %rsp + leaq (__end_init_task - PTREGS_SIZE)(%rip), %rsp /* Set up %gs. * From patchwork Sun Feb 26 11:07:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13152361 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 46DCEC7EE2D for ; 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Sun, 26 Feb 2023 03:08:10 -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 07/11] x86/smpboot: Remove early_gdt_descr on 64-bit Date: Sun, 26 Feb 2023 11:07:58 +0000 Message-Id: <20230226110802.103134-8-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: Brian Gerst Build the GDT descriptor on the stack instead. Signed-off-by: Brian Gerst Reviewed-by: David Woodhouse Signed-off-by: David Woodhouse Tested-by: Usama Arif Signed-off-by: Usama Arif Signed-off-by: David Woodhouse --- arch/x86/kernel/acpi/sleep.c | 2 -- arch/x86/kernel/head_64.S | 11 ++++++----- arch/x86/kernel/smpboot.c | 2 +- 3 files changed, 7 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c index ab6e29b32c04..236f2423454d 100644 --- a/arch/x86/kernel/acpi/sleep.c +++ b/arch/x86/kernel/acpi/sleep.c @@ -112,8 +112,6 @@ int x86_acpi_suspend_lowlevel(void) #else /* CONFIG_64BIT */ #ifdef CONFIG_SMP current->thread.sp = (unsigned long)temp_stack + sizeof(temp_stack); - early_gdt_descr.address = - (unsigned long)get_cpu_gdt_rw(smp_processor_id()); initial_gs = per_cpu_offset(smp_processor_id()); smpboot_control = smp_processor_id(); #endif diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 5a2417d788d1..0ccca297e90e 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -265,7 +265,12 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) * addresses where we're currently running on. We have to do that here * because in 32bit we couldn't load a 64bit linear address. */ - lgdt early_gdt_descr(%rip) + subq $16, %rsp + movw $(GDT_SIZE-1), (%rsp) + leaq gdt_page(%rdx), %rax + movq %rax, 2(%rsp) + lgdt (%rsp) + addq $16, %rsp /* set up data segments */ xorl %eax,%eax @@ -667,10 +672,6 @@ SYM_DATA_END(level1_fixmap_pgt) .data .align 16 -SYM_DATA(early_gdt_descr, .word GDT_ENTRIES*8-1) -SYM_DATA_LOCAL(early_gdt_descr_base, .quad INIT_PER_CPU_VAR(gdt_page)) - - .align 16 SYM_DATA(smpboot_control, .long 0) .align 16 diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 62e3bf37f0b8..a22460a07cf8 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1110,10 +1110,10 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle, start_ip = real_mode_header->trampoline_start64; #endif idle->thread.sp = (unsigned long)task_pt_regs(idle); - early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(cpu); initial_code = (unsigned long)start_secondary; 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Sun, 26 Feb 2023 03:08:11 -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 08/11] x86/smpboot: Remove initial_gs Date: Sun, 26 Feb 2023 11:07:59 +0000 Message-Id: <20230226110802.103134-9-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: Brian Gerst Use the percpu offset directly to set GSBASE. Signed-off-by: Brian Gerst Reviewed-by: David Woodhouse Signed-off-by: David Woodhouse Tested-by: Usama Arif Signed-off-by: Usama Arif Signed-off-by: David Woodhouse --- arch/x86/include/asm/realmode.h | 1 - arch/x86/kernel/acpi/sleep.c | 1 - arch/x86/kernel/head_64.S | 22 ++++++++-------------- arch/x86/kernel/smpboot.c | 2 -- 4 files changed, 8 insertions(+), 18 deletions(-) diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h index a336feef0af1..f6a1737c77be 100644 --- a/arch/x86/include/asm/realmode.h +++ b/arch/x86/include/asm/realmode.h @@ -59,7 +59,6 @@ extern struct real_mode_header *real_mode_header; extern unsigned char real_mode_blob_end[]; extern unsigned long initial_code; -extern unsigned long initial_gs; extern unsigned long initial_stack; #ifdef CONFIG_AMD_MEM_ENCRYPT extern unsigned long initial_vc_handler; diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c index 236f2423454d..9d2d88424c77 100644 --- a/arch/x86/kernel/acpi/sleep.c +++ b/arch/x86/kernel/acpi/sleep.c @@ -112,7 +112,6 @@ int x86_acpi_suspend_lowlevel(void) #else /* CONFIG_64BIT */ #ifdef CONFIG_SMP current->thread.sp = (unsigned long)temp_stack + sizeof(temp_stack); - initial_gs = per_cpu_offset(smp_processor_id()); smpboot_control = smp_processor_id(); #endif initial_code = (unsigned long)wakeup_long64; diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 0ccca297e90e..069191e33490 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -66,18 +66,10 @@ SYM_CODE_START_NOALIGN(startup_64) leaq _text(%rip), %rdi - /* - * initial_gs points to initial fixed_percpu_data struct with storage for - * the stack protector canary. Global pointer fixups are needed at this - * stage, so apply them as is done in fixup_pointer(), and initialize %gs - * such that the canary can be accessed at %gs:40 for subsequent C calls. - */ + /* Setup GSBASE to allow stack canary access for C code */ movl $MSR_GS_BASE, %ecx - movq initial_gs(%rip), %rax - movq $_text, %rdx - subq %rdx, %rax - addq %rdi, %rax - movq %rax, %rdx + leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx + movl %edx, %eax shrq $32, %rdx wrmsr @@ -294,8 +286,11 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) * the per cpu areas are set up. */ movl $MSR_GS_BASE,%ecx - movl initial_gs(%rip),%eax - movl initial_gs+4(%rip),%edx +#ifndef CONFIG_SMP + leaq INIT_PER_CPU_VAR(fixed_percpu_data)(%rip), %rdx +#endif + movl %edx, %eax + shrq $32, %rdx wrmsr /* Setup and Load IDT */ @@ -437,7 +432,6 @@ SYM_CODE_END(vc_boot_ghcb) __REFDATA .balign 8 SYM_DATA(initial_code, .quad x86_64_start_kernel) -SYM_DATA(initial_gs, .quad INIT_PER_CPU_VAR(fixed_percpu_data)) #ifdef CONFIG_AMD_MEM_ENCRYPT SYM_DATA(initial_vc_handler, .quad handle_vc_boot_ghcb) #endif diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index a22460a07cf8..b04520085582 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1084,8 +1084,6 @@ int common_cpu_up(unsigned int cpu, struct task_struct *idle) #ifdef CONFIG_X86_32 /* Stack for startup_32 can be just as for start_secondary onwards */ per_cpu(pcpu_hot.top_of_stack, cpu) = task_top_of_stack(idle); 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Sun, 26 Feb 2023 03:08:12 -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 09/11] x86/smpboot: Support parallel startup of secondary CPUs Date: Sun, 26 Feb 2023 11:08:00 +0000 Message-Id: <20230226110802.103134-10-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 Rework the real-mode startup code to allow for APs to be brought up in parallel. This is in two parts: 1. Introduce a bit-spinlock to prevent them from all using the real mode stack at the same time. 2. Avoid needing to use the global smpboot_control variable to pass each AP its CPU#. To achieve the latter, export the cpuid_to_apicid[] array so that each AP can find its own CPU# by searching therein based on its APIC ID. Introduce flags in the top bits of smpboot_control which indicate methods by which an AP should find its CPU#. For a serialized bringup, the CPU# is explicitly passed in the low bits of smpboot_control as before. For parallel mode there are flags directing the AP to find its APIC ID in CPUID leaf 0x0b (for X2APIC mode) or CPUID leaf 0x01 where 8 bits are sufficient, then perform the cpuid_to_apicid[] lookup with that. Parallel startup may be disabled by a command line option, and also if: • AMD SEV-ES is in use, since the AP may not use CPUID that early. • X2APIC is enabled, but CPUID leaf 0xb is not present and correect. • X2APIC is not enabled but not even CPUID leaf 0x01 exists. Aside from the fact that APs will now look up their CPU# via the newly-exported cpuid_to_apicid[] table, there is no behavioural change intended yet, since new parallel CPUHP states have not — yet — been added. [ tglx: Initial proof of concept patch with bitlock and APIC ID lookup ] [ dwmw2: Rework and testing, commit message, CPUID 0x1 and CPU0 support ] [ seanc: Fix stray override of initial_gs in common_cpu_up() ] [ Oleksandr Natalenko: reported suspend/resume issue fixed in x86_acpi_suspend_lowlevel ] Co-developed-by: Thomas Gleixner Co-developed-by: Brian Gerst Signed-off-by: Thomas Gleixner Signed-off-by: Brian Gerst Signed-off-by: David Woodhouse Signed-off-by: Usama Arif Tested-by: Paul E. McKenney Tested-by: Kim Phillips Tested-by: Oleksandr Natalenko --- .../admin-guide/kernel-parameters.txt | 3 + arch/x86/include/asm/realmode.h | 3 + arch/x86/include/asm/smp.h | 6 ++ arch/x86/kernel/acpi/sleep.c | 9 ++- arch/x86/kernel/apic/apic.c | 2 +- arch/x86/kernel/head_64.S | 63 ++++++++++++++++++- arch/x86/kernel/smpboot.c | 53 +++++++++++++++- arch/x86/realmode/init.c | 3 + arch/x86/realmode/rm/trampoline_64.S | 27 ++++++-- 9 files changed, 159 insertions(+), 10 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 6cfa6e3996cf..ee099b8aac6d 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3819,6 +3819,9 @@ nomodule Disable module load + no_parallel_bringup + [X86,SMP] Disable parallel brinugp of secondary cores. + nopat [X86] Disable PAT (page attribute table extension of pagetables) support. diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h index f6a1737c77be..87e5482acd0d 100644 --- a/arch/x86/include/asm/realmode.h +++ b/arch/x86/include/asm/realmode.h @@ -52,6 +52,7 @@ struct trampoline_header { u64 efer; u32 cr4; u32 flags; + u32 lock; #endif }; @@ -64,6 +65,8 @@ extern unsigned long initial_stack; extern unsigned long initial_vc_handler; #endif +extern u32 *trampoline_lock; + extern unsigned char real_mode_blob[]; extern unsigned char real_mode_relocs[]; diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h index bf2c51df9e0b..1cf4f1e57570 100644 --- a/arch/x86/include/asm/smp.h +++ b/arch/x86/include/asm/smp.h @@ -203,4 +203,10 @@ extern unsigned int smpboot_control; #endif /* !__ASSEMBLY__ */ +/* Control bits for startup_64 */ +#define STARTUP_APICID_CPUID_0B 0x80000000 +#define STARTUP_APICID_CPUID_01 0x40000000 + +#define STARTUP_PARALLEL_MASK (STARTUP_APICID_CPUID_01 | STARTUP_APICID_CPUID_0B) + #endif /* _ASM_X86_SMP_H */ diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c index 9d2d88424c77..5dcf5ca15383 100644 --- a/arch/x86/kernel/acpi/sleep.c +++ b/arch/x86/kernel/acpi/sleep.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include "../../realmode/rm/wakeup.h" @@ -112,7 +113,13 @@ int x86_acpi_suspend_lowlevel(void) #else /* CONFIG_64BIT */ #ifdef CONFIG_SMP current->thread.sp = (unsigned long)temp_stack + sizeof(temp_stack); - smpboot_control = smp_processor_id(); + /* + * Ensure the CPU knows which one it is when it comes back, if + * it isn't in parallel mode and expected to work that out for + * itself. + */ + if (!(smpboot_control & STARTUP_PARALLEL_MASK)) + smpboot_control = smp_processor_id(); #endif initial_code = (unsigned long)wakeup_long64; saved_magic = 0x123456789abcdef0L; diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 20d9a604da7c..ac1d7e5da1f2 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -2377,7 +2377,7 @@ static int nr_logical_cpuids = 1; /* * Used to store mapping between logical CPU IDs and APIC IDs. */ -static int cpuid_to_apicid[] = { +int cpuid_to_apicid[] = { [0 ... NR_CPUS - 1] = -1, }; diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 069191e33490..17bdd6122dca 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -25,6 +25,7 @@ #include #include #include +#include /* * We are not able to switch in one step to the final KERNEL ADDRESS SPACE @@ -234,8 +235,57 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) ANNOTATE_NOENDBR // above #ifdef CONFIG_SMP + /* + * For parallel boot, the APIC ID is retrieved from CPUID, and then + * used to look up the CPU number. For booting a single CPU, the + * CPU number is encoded in smpboot_control. + * + * Bit 31 STARTUP_APICID_CPUID_0B flag (use CPUID 0x0b) + * Bit 30 STARTUP_APICID_CPUID_01 flag (use CPUID 0x01) + * Bit 0-24 CPU# if STARTUP_APICID_CPUID_xx flags are not set + */ movl smpboot_control(%rip), %ecx + testl $STARTUP_APICID_CPUID_0B, %ecx + jnz .Luse_cpuid_0b + testl $STARTUP_APICID_CPUID_01, %ecx + jnz .Luse_cpuid_01 + andl $0x0FFFFFFF, %ecx + jmp .Lsetup_cpu + +.Luse_cpuid_01: + mov $0x01, %eax + cpuid + mov %ebx, %edx + shr $24, %edx + jmp .Lsetup_AP + +.Luse_cpuid_0b: + mov $0x0B, %eax + xorl %ecx, %ecx + cpuid + +.Lsetup_AP: + /* EDX contains the APIC ID of the current CPU */ + xorq %rcx, %rcx + leaq cpuid_to_apicid(%rip), %rbx +.Lfind_cpunr: + cmpl (%rbx,%rcx,4), %edx + jz .Lsetup_cpu + inc %ecx + cmpl nr_cpu_ids(%rip), %ecx + jb .Lfind_cpunr + + /* APIC ID not found in the table. Drop the trampoline lock and bail. */ + movq trampoline_lock(%rip), %rax + lock + btrl $0, (%rax) + +1: cli + hlt + jmp 1b + +.Lsetup_cpu: /* Get the per cpu offset for the given CPU# which is in ECX */ movq __per_cpu_offset(,%rcx,8), %rdx #else @@ -244,7 +294,7 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) /* * Setup a boot time stack - Any secondary CPU will have lost its stack - * by now because the cr3-switch above unmaps the real-mode stack. + * by now because the cr3-switch above unmaps the real-mode stack * * RDX contains the per-cpu offset */ @@ -293,6 +343,14 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) shrq $32, %rdx wrmsr + /* Drop the realmode protection. For the boot CPU the pointer is NULL! */ + movq trampoline_lock(%rip), %rax + testq %rax, %rax + jz .Lsetup_idt + lock + btrl $0, (%rax) + +.Lsetup_idt: /* Setup and Load IDT */ pushq %rsi call early_setup_idt @@ -435,6 +493,8 @@ SYM_DATA(initial_code, .quad x86_64_start_kernel) #ifdef CONFIG_AMD_MEM_ENCRYPT SYM_DATA(initial_vc_handler, .quad handle_vc_boot_ghcb) #endif + +SYM_DATA(trampoline_lock, .quad 0); __FINITDATA __INIT @@ -665,7 +725,6 @@ SYM_DATA_END(level1_fixmap_pgt) .data .align 16 - SYM_DATA(smpboot_control, .long 0) .align 16 diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index b04520085582..19b9b89b7458 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -797,6 +797,16 @@ static int __init cpu_init_udelay(char *str) } early_param("cpu_init_udelay", cpu_init_udelay); +static bool do_parallel_bringup __ro_after_init = true; + +static int __init no_parallel_bringup(char *str) +{ + do_parallel_bringup = false; + + return 0; +} +early_param("no_parallel_bringup", no_parallel_bringup); + static void __init smp_quirk_init_udelay(void) { /* if cmdline changed it from default, leave it alone */ @@ -1113,7 +1123,7 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle, if (IS_ENABLED(CONFIG_X86_32)) { early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(cpu); initial_stack = idle->thread.sp; - } else { + } else if (!do_parallel_bringup) { smpboot_control = cpu; } @@ -1515,6 +1525,47 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) speculative_store_bypass_ht_init(); + /* + * We can do 64-bit AP bringup in parallel if the CPU reports + * its APIC ID in CPUID (either leaf 0x0B if we need the full + * APIC ID in X2APIC mode, or leaf 0x01 if 8 bits are + * sufficient). Otherwise it's too hard. And not for SEV-ES + * guests because they can't use CPUID that early. + */ + if (IS_ENABLED(CONFIG_X86_32) || boot_cpu_data.cpuid_level < 1 || + (x2apic_mode && boot_cpu_data.cpuid_level < 0xb) || + cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) + do_parallel_bringup = false; + + if (do_parallel_bringup && x2apic_mode) { + unsigned int eax, ebx, ecx, edx; + + /* + * To support parallel bringup in x2apic mode, the AP will need + * to obtain its APIC ID from CPUID 0x0B, since CPUID 0x01 has + * only 8 bits. Check that it is present and seems correct. + */ + cpuid_count(0xb, 0, &eax, &ebx, &ecx, &edx); + + /* + * AMD says that if executed with an umimplemented level in + * ECX, then it will return all zeroes in EAX. Intel says it + * will return zeroes in both EAX and EBX. Checking only EAX + * should be sufficient. + */ + if (eax) { + pr_debug("Using CPUID 0xb for parallel CPU startup\n"); + smpboot_control = STARTUP_APICID_CPUID_0B; + } else { + pr_info("Disabling parallel bringup because CPUID 0xb looks untrustworthy\n"); + do_parallel_bringup = false; + } + } else if (do_parallel_bringup) { + /* Without X2APIC, what's in CPUID 0x01 should suffice. */ + pr_debug("Using CPUID 0x1 for parallel CPU startup\n"); + smpboot_control = STARTUP_APICID_CPUID_01; + } + snp_set_wakeup_secondary_cpu(); } diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c index af565816d2ba..788e5559549f 100644 --- a/arch/x86/realmode/init.c +++ b/arch/x86/realmode/init.c @@ -154,6 +154,9 @@ static void __init setup_real_mode(void) trampoline_header->flags = 0; + trampoline_lock = &trampoline_header->lock; + *trampoline_lock = 0; + trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd); /* Map the real mode stub as virtual == physical */ diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S index e38d61d6562e..2dfb1c400167 100644 --- a/arch/x86/realmode/rm/trampoline_64.S +++ b/arch/x86/realmode/rm/trampoline_64.S @@ -37,6 +37,24 @@ .text .code16 +.macro LOAD_REALMODE_ESP + /* + * Make sure only one CPU fiddles with the realmode stack + */ +.Llock_rm\@: + btl $0, tr_lock + jnc 2f + pause + jmp .Llock_rm\@ +2: + lock + btsl $0, tr_lock + jc .Llock_rm\@ + + # Setup stack + movl $rm_stack_end, %esp +.endm + .balign PAGE_SIZE SYM_CODE_START(trampoline_start) cli # We should be safe anyway @@ -49,8 +67,7 @@ SYM_CODE_START(trampoline_start) mov %ax, %es mov %ax, %ss - # Setup stack - movl $rm_stack_end, %esp + LOAD_REALMODE_ESP call verify_cpu # Verify the cpu supports long mode testl %eax, %eax # Check for return code @@ -93,8 +110,7 @@ SYM_CODE_START(sev_es_trampoline_start) mov %ax, %es mov %ax, %ss - # Setup stack - movl $rm_stack_end, %esp + LOAD_REALMODE_ESP jmp .Lswitch_to_protected SYM_CODE_END(sev_es_trampoline_start) @@ -177,7 +193,7 @@ SYM_CODE_START(pa_trampoline_compat) * In compatibility mode. Prep ESP and DX for startup_32, then disable * paging and complete the switch to legacy 32-bit mode. */ - movl $rm_stack_end, %esp + LOAD_REALMODE_ESP movw $__KERNEL_DS, %dx movl $(CR0_STATE & ~X86_CR0_PG), %eax @@ -241,6 +257,7 @@ SYM_DATA_START(trampoline_header) SYM_DATA(tr_efer, .space 8) SYM_DATA(tr_cr4, .space 4) SYM_DATA(tr_flags, .space 4) + SYM_DATA(tr_lock, .space 4) SYM_DATA_END(trampoline_header) #include "trampoline_common.S" From patchwork Sun Feb 26 11:08:01 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13152364 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 EF999C6FA8E for ; Sun, 26 Feb 2023 11:09:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229805AbjBZLJ0 (ORCPT ); Sun, 26 Feb 2023 06:09:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35936 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229776AbjBZLJE (ORCPT ); Sun, 26 Feb 2023 06:09:04 -0500 Received: from mail-wm1-x334.google.com (mail-wm1-x334.google.com [IPv6:2a00:1450:4864:20::334]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E7DBEC4D for ; Sun, 26 Feb 2023 03:08:15 -0800 (PST) Received: by mail-wm1-x334.google.com with SMTP id t25-20020a1c7719000000b003eb052cc5ccso4824918wmi.4 for ; Sun, 26 Feb 2023 03:08:15 -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=Rv4YBkExnEbzjmvRGSVdLlKzdSs1hoLH3+gZkX3hIJM=; b=DJ0qn754KoOY7lszedXqM0cvktd4MIlEDstLHXsvijRzw7VZtckVr4f+/5tRRSmKHU gdDRywi3/sCcc7cHk3Z1pMDmtOJBx42sx44E2WV0E5kwwaYFh0qPiytCfjob5b6Whm6M JoD/FuFOZZRjwBfN/BXF6UWeFn4h1MBx/LQRtZGy6q9qXLvTqOP1wlhSDMW34m8nEXIL 5j4L2Hm+EO5Z2aUvxXx4NkNje0MQfjveISORHATz2z5n4bl/Cjjio/sv53EwV2Lz9yR4 ZLxVoK7Ra+QQNJID4t6OiAb0CvXGuzbUjPqd8warO8sN+vc5QX5e09GyuhHyU4um/Lo4 3BHA== 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=Rv4YBkExnEbzjmvRGSVdLlKzdSs1hoLH3+gZkX3hIJM=; b=uhWZAUeMq0+FuLevtYYVONcFXmFsDnMagn5ZmDVDmJOTwDzFV0G3eXRVIDgLFfijgw P3D3MBhgDd1HnOTNmq7a+IlTMjhPzDN7L7miFvvHs4c/HRZzgghMpBHk/U42qIVPZjaX hD0/AzDsKtuba4IsL9nUv31LCCaJlxv91TbsuVwBO1ZrG5emnlUW8Noo2xmU3d6HvS79 3YtC2o9HrD+IKhBpUpi5F1LGJZ2kF4Dz5hTu2nVrsC4fiKOObO5etETlX0W/JKaIJdEy Uv5YK0aXZpmaaum83W3ALTO/NRqRx5bQAZQIJGRV1RDCr1MUkLKKkWoKKkjnLtMTZj92 IKIg== X-Gm-Message-State: AO0yUKUzOVnf5YJ/hWI6plbaddGf4OaAG9TABAGDQcSKlGzo5rpoit28 LLfIyAGu4cd9yn1e7OmOj2Wk9w== X-Google-Smtp-Source: AK7set8mHGT2VnCThEqOMgIy/Fuquza1CoWNEJQk3uaHqxCiEMo9Z60UV7yiXPOSZC5v+cIlL4JZnw== X-Received: by 2002:a05:600c:4da3:b0:3eb:2da4:f304 with SMTP id v35-20020a05600c4da300b003eb2da4f304mr5025546wmp.17.1677409693572; Sun, 26 Feb 2023 03:08:13 -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.25.2023.02.26.03.08.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 26 Feb 2023 03:08:13 -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 10/11] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel Date: Sun, 26 Feb 2023 11:08:01 +0000 Message-Id: <20230226110802.103134-11-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 the APs can find their own APIC ID without assistance, perform the AP bringup in parallel. Register a CPUHP_BP_PARALLEL_DYN stage "x86/cpu:kick" which just calls do_boot_cpu() to deliver INIT/SIPI/SIPI to each AP in turn before the normal native_cpu_up() does the rest of the hand-holding. The APs will then take turns through the real mode code (which has its own bitlock for exclusion) until they make it to their own stack, then proceed through the first few lines of start_secondary() and execute these parts in parallel: start_secondary() -> cr4_init() -> (some 32-bit only stuff so not in the parallel cases) -> cpu_init_secondary() -> cpu_init_exception_handling() -> cpu_init() -> wait_for_master_cpu() At this point they wait for the BSP to set their bit in cpu_callout_mask (from do_wait_cpu_initialized()), and release them to continue through the rest of cpu_init() and beyond. This reduces the time taken for bringup on my 28-thread Haswell system from about 120ms to 80ms. On a socket 96-thread Skylake it takes the bringup time from 500ms to 100ms. There is more speedup to be had by doing the remaining parts in parallel too — especially notify_cpu_starting() in which the AP takes itself through all the stages from CPUHP_BRINGUP_CPU to CPUHP_ONLINE. But those require careful auditing to ensure they are reentrant, before we can go that far. 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 | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 19b9b89b7458..711573cd9b87 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -57,6 +57,7 @@ #include #include #include +#include #include #include @@ -1325,9 +1326,12 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle) { int ret; - ret = do_cpu_up(cpu, tidle); - if (ret) - return ret; + /* If parallel AP bringup isn't enabled, perform the first steps now. */ + if (!do_parallel_bringup) { + ret = do_cpu_up(cpu, tidle); + if (ret) + return ret; + } ret = do_wait_cpu_initialized(cpu); if (ret) @@ -1349,6 +1353,12 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle) return ret; } +/* Bringup step one: Send INIT/SIPI to the target AP */ +static int native_cpu_kick(unsigned int cpu) +{ + return do_cpu_up(cpu, idle_thread_get(cpu)); +} + /** * arch_disable_smp_support() - disables SMP support for x86 at runtime */ @@ -1566,6 +1576,11 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) smpboot_control = STARTUP_APICID_CPUID_01; } + if (do_parallel_bringup) { + cpuhp_setup_state_nocalls(CPUHP_BP_PARALLEL_DYN, "x86/cpu:kick", + native_cpu_kick, NULL); + } + snp_set_wakeup_secondary_cpu(); } From patchwork Sun Feb 26 11:08:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13152363 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 755EFC7EE30 for ; Sun, 26 Feb 2023 11:09:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229794AbjBZLJY (ORCPT ); Sun, 26 Feb 2023 06:09:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229675AbjBZLJD (ORCPT ); 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Sun, 26 Feb 2023 03:08:14 -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 11/11] x86/smpboot: Serialize topology updates for secondary bringup Date: Sun, 26 Feb 2023 11:08:02 +0000 Message-Id: <20230226110802.103134-12-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 The toplogy update is performed by the AP via smp_callin() after the BSP has called do_wait_cpu_initialized(), setting the AP's bit in cpu_callout_mask to allow it to proceed. In preparation to enable further parallelism of AP bringup, add locking to serialize the update even if multiple APs are (in future) permitted to proceed through the next stages of bringup in parallel. Without such ordering (and with that future extra parallelism), confusion ensues: [ 1.360149] x86: Booting SMP configuration: [ 1.360221] .... node #0, CPUs: #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14 #15 #16 #17 #18 #19 #20 #21 #22 #23 [ 1.366225] .... node #1, CPUs: #24 #25 #26 #27 #28 #29 #30 #31 #32 #33 #34 #35 #36 #37 #38 #39 #40 #41 #42 #43 #44 #45 #46 #47 [ 1.370219] .... node #0, CPUs: #48 #49 #50 #51 #52 #53 #54 #55 #56 #57 #58 #59 #60 #61 #62 #63 #64 #65 #66 #67 #68 #69 #70 #71 [ 1.378226] .... node #1, CPUs: #72 #73 #74 #75 #76 #77 #78 #79 #80 #81 #82 #83 #84 #85 #86 #87 #88 #89 #90 #91 #92 #93 #94 #95 [ 1.382037] Brought 96 CPUs to x86/cpu:kick in 72232606 cycles [ 0.104104] smpboot: CPU 26 Converting physical 0 to logical die 1 [ 0.104104] smpboot: CPU 27 Converting physical 1 to logical package 2 [ 0.104104] smpboot: CPU 24 Converting physical 1 to logical package 3 [ 0.104104] smpboot: CPU 27 Converting physical 0 to logical die 2 [ 0.104104] smpboot: CPU 25 Converting physical 1 to logical package 4 [ 1.385609] Brought 96 CPUs to x86/cpu:wait-init in 9269218 cycles [ 1.395285] Brought CPUs online in 28930764 cycles [ 1.395469] smp: Brought up 2 nodes, 96 CPUs [ 1.395689] smpboot: Max logical packages: 2 [ 1.396222] smpboot: Total of 96 processors activated (576000.00 BogoMIPS) 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/include/asm/smp.h | 4 +- arch/x86/include/asm/topology.h | 2 - arch/x86/kernel/cpu/common.c | 6 +-- arch/x86/kernel/smpboot.c | 73 ++++++++++++++++++++------------- arch/x86/xen/smp_pv.c | 4 +- 5 files changed, 48 insertions(+), 41 deletions(-) diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h index 1cf4f1e57570..defe76ee9e64 100644 --- a/arch/x86/include/asm/smp.h +++ b/arch/x86/include/asm/smp.h @@ -48,8 +48,6 @@ struct smp_ops { }; /* Globals due to paravirt */ -extern void set_cpu_sibling_map(int cpu); - #ifdef CONFIG_SMP extern struct smp_ops smp_ops; @@ -137,7 +135,7 @@ void native_send_call_func_single_ipi(int cpu); void x86_idle_thread_init(unsigned int cpu, struct task_struct *idle); void smp_store_boot_cpu_info(void); -void smp_store_cpu_info(int id); +void smp_store_cpu_info(int id, bool force_single_core); asmlinkage __visible void smp_reboot_interrupt(void); __visible void smp_reschedule_interrupt(struct pt_regs *regs); diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index 458c891a8273..4bccbd949a99 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -136,8 +136,6 @@ static inline int topology_max_smt_threads(void) return __max_smt_threads; } -int topology_update_package_map(unsigned int apicid, unsigned int cpu); -int topology_update_die_map(unsigned int dieid, unsigned int cpu); int topology_phys_to_logical_pkg(unsigned int pkg); int topology_phys_to_logical_die(unsigned int die, unsigned int cpu); bool topology_is_primary_thread(unsigned int cpu); diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index f3cc7699e1e1..06d7f9e55d45 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1771,7 +1771,7 @@ static void generic_identify(struct cpuinfo_x86 *c) * Validate that ACPI/mptables have the same information about the * effective APIC id and update the package map. */ -static void validate_apic_and_package_id(struct cpuinfo_x86 *c) +static void validate_apic_id(struct cpuinfo_x86 *c) { #ifdef CONFIG_SMP unsigned int apicid, cpu = smp_processor_id(); @@ -1782,8 +1782,6 @@ static void validate_apic_and_package_id(struct cpuinfo_x86 *c) pr_err(FW_BUG "CPU%u: APIC id mismatch. Firmware: %x APIC: %x\n", cpu, apicid, c->initial_apicid); } - BUG_ON(topology_update_package_map(c->phys_proc_id, cpu)); - BUG_ON(topology_update_die_map(c->cpu_die_id, cpu)); #else c->logical_proc_id = 0; #endif @@ -1974,7 +1972,7 @@ void identify_secondary_cpu(struct cpuinfo_x86 *c) #ifdef CONFIG_X86_32 enable_sep_cpu(); #endif - validate_apic_and_package_id(c); + validate_apic_id(c); x86_spec_ctrl_setup_ap(); update_srbds_msr(); diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 711573cd9b87..9d956571ecc1 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -180,16 +180,12 @@ static void smp_callin(void) apic_ap_setup(); /* - * Save our processor parameters. Note: this information - * is needed for clock calibration. - */ - smp_store_cpu_info(cpuid); - - /* + * Save our processor parameters and update topology. + * Note: this information is needed for clock calibration. * The topology information must be up to date before * calibrate_delay() and notify_cpu_starting(). */ - set_cpu_sibling_map(raw_smp_processor_id()); + smp_store_cpu_info(cpuid, false); ap_init_aperfmperf(); @@ -243,6 +239,12 @@ static void notrace start_secondary(void *unused) * its bit in cpu_callout_mask to release it. */ cpu_init_secondary(); + + /* + * Even though notify_cpu_starting() will do this, it does so too late + * as the AP may already have triggered lockdep splats by then. See + * commit 29368e093 ("x86/smpboot: Move rcu_cpu_starting() earlier"). + */ rcu_cpu_starting(raw_smp_processor_id()); x86_cpuinit.early_percpu_clock_init(); @@ -351,7 +353,7 @@ EXPORT_SYMBOL(topology_phys_to_logical_die); * @pkg: The physical package id as retrieved via CPUID * @cpu: The cpu for which this is updated */ -int topology_update_package_map(unsigned int pkg, unsigned int cpu) +static int topology_update_package_map(unsigned int pkg, unsigned int cpu) { int new; @@ -374,7 +376,7 @@ int topology_update_package_map(unsigned int pkg, unsigned int cpu) * @die: The die id as retrieved via CPUID * @cpu: The cpu for which this is updated */ -int topology_update_die_map(unsigned int die, unsigned int cpu) +static int topology_update_die_map(unsigned int die, unsigned int cpu) { int new; @@ -405,25 +407,7 @@ void __init smp_store_boot_cpu_info(void) c->initialized = true; } -/* - * The bootstrap kernel entry code has set these up. Save them for - * a given CPU - */ -void smp_store_cpu_info(int id) -{ - struct cpuinfo_x86 *c = &cpu_data(id); - - /* Copy boot_cpu_data only on the first bringup */ - if (!c->initialized) - *c = boot_cpu_data; - c->cpu_index = id; - /* - * During boot time, CPU0 has this setup already. Save the info when - * bringing up AP or offlined CPU0. - */ - identify_secondary_cpu(c); - c->initialized = true; -} +static arch_spinlock_t topology_lock = __ARCH_SPIN_LOCK_UNLOCKED; static bool topology_same_node(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o) @@ -629,7 +613,7 @@ static struct sched_domain_topology_level x86_topology[] = { */ static bool x86_has_numa_in_package; -void set_cpu_sibling_map(int cpu) +static void set_cpu_sibling_map(int cpu) { bool has_smt = smp_num_siblings > 1; bool has_mp = has_smt || boot_cpu_data.x86_max_cores > 1; @@ -708,6 +692,37 @@ void set_cpu_sibling_map(int cpu) } } +/* + * The bootstrap kernel entry code has set these up. Save them for + * a given CPU + */ +void smp_store_cpu_info(int id, bool force_single_core) +{ + struct cpuinfo_x86 *c = &cpu_data(id); + + /* Copy boot_cpu_data only on the first bringup */ + if (!c->initialized) + *c = boot_cpu_data; + c->cpu_index = id; + /* + * During boot time, CPU0 has this setup already. Save the info when + * bringing up AP or offlined CPU0. + */ + identify_secondary_cpu(c); + + arch_spin_lock(&topology_lock); + BUG_ON(topology_update_package_map(c->phys_proc_id, id)); + BUG_ON(topology_update_die_map(c->cpu_die_id, id)); + c->initialized = true; + + /* For Xen PV */ + if (force_single_core) + c->x86_max_cores = 1; + + set_cpu_sibling_map(id); + arch_spin_unlock(&topology_lock); +} + /* maps the cpu to the sched domain representing multi-core */ const struct cpumask *cpu_coregroup_mask(int cpu) { diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c index 6175f2c5c822..09f94f940689 100644 --- a/arch/x86/xen/smp_pv.c +++ b/arch/x86/xen/smp_pv.c @@ -71,9 +71,7 @@ static void cpu_bringup(void) xen_enable_syscall(); } cpu = smp_processor_id(); - smp_store_cpu_info(cpu); - cpu_data(cpu).x86_max_cores = 1; - set_cpu_sibling_map(cpu); + smp_store_cpu_info(cpu, true); speculative_store_bypass_ht_init();