From: David Woodhouse <dwmw2@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
rcu@vger.kernel.org, mimoja@mimoja.de, hewenliang4@huawei.com,
hushiyuan@huawei.com, luolongjun@huawei.com,
hejingxian@huawei.com
Subject: [PATCH 06/11] x86/smpboot: Split up native_cpu_up into separate phases
Date: Thu, 9 Dec 2021 15:09:33 +0000 [thread overview]
Message-ID: <20211209150938.3518-7-dwmw2@infradead.org> (raw)
In-Reply-To: <20211209150938.3518-1-dwmw2@infradead.org>
From: David Woodhouse <dwmw@amazon.co.uk>
There are four logical parts to what native_cpu_up() does.
First it actually wakes the AP.
Second, it waits for the AP to make it as far as wait_for_master_cpu()
which sets that CPU's bit in cpu_initialized_mask, and sets the bit in
cpu_callout_mask to let the AP proceed through cpu_init().
Then, it waits 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.
Finally, it does the TSC synchronization and waits for the AP to actually
mark itself online in cpu_online_mask.
This commit should have no behavioural change, but merely splits those
phases out into separate functions so that future commits can make them
happen in parallel for all APs.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
arch/x86/kernel/smpboot.c | 136 +++++++++++++++++++++++---------------
1 file changed, 82 insertions(+), 54 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 99c705935f94..11ef434a93a1 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1080,9 +1080,7 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle,
{
/* start_ip had better be page-aligned! */
unsigned long start_ip = real_mode_header->trampoline_start;
-
unsigned long boot_error = 0;
- unsigned long timeout;
idle->thread.sp = (unsigned long)task_pt_regs(idle);
early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(cpu);
@@ -1135,55 +1133,70 @@ 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();
+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;
+}
+
+static int do_wait_cpu_callin(unsigned int cpu)
+{
+ /*
+ * Wait till AP completes initial initialization.
+ */
+ return do_wait_cpu_cpumask(cpu, cpu_callin_mask);
+}
+
+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);
+
+ 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)
+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();
@@ -1230,19 +1243,6 @@ 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
@@ -1254,6 +1254,34 @@ 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
*/
--
2.31.1
next prev parent reply other threads:[~2021-12-09 15:10 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-09 15:09 [PATCH 00/11] Parallel CPU bringup for x86_64 David Woodhouse
2021-12-09 15:09 ` [PATCH 01/11] x86/apic/x2apic: Fix parallel handling of cluster_mask David Woodhouse
2021-12-09 15:09 ` [PATCH 02/11] rcu: Kill rnp->ofl_seq and use only rcu_state.ofl_lock for exclusion David Woodhouse
2021-12-09 17:18 ` Paul E. McKenney
2021-12-09 18:52 ` David Woodhouse
2021-12-09 18:31 ` Neeraj Upadhyay
2021-12-09 18:43 ` David Woodhouse
2021-12-09 19:21 ` [PATCH v1.1 " David Woodhouse
2021-12-10 4:26 ` Neeraj Upadhyay
2021-12-13 8:57 ` David Woodhouse
2021-12-13 9:11 ` Neeraj Upadhyay
2021-12-09 15:09 ` [PATCH 03/11] rcu: Add mutex for rcu boost kthread spawning and affinity setting David Woodhouse
2021-12-09 17:20 ` Paul E. McKenney
2021-12-09 15:09 ` [PATCH 04/11] cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU David Woodhouse
2021-12-09 15:09 ` [PATCH 05/11] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() David Woodhouse
2021-12-09 15:09 ` David Woodhouse [this message]
2021-12-09 15:09 ` [PATCH 07/11] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> David Woodhouse
2021-12-09 15:09 ` [PATCH 08/11] x86/tsc: Avoid synchronizing TSCs with multiple CPUs in parallel David Woodhouse
2021-12-09 15:43 ` Peter Zijlstra
2021-12-09 15:50 ` David Woodhouse
2021-12-09 15:09 ` [PATCH 09/11] x86/boot: Support parallel startup of secondary CPUs David Woodhouse
2021-12-09 15:50 ` Peter Zijlstra
2021-12-14 11:33 ` David Woodhouse
2021-12-09 15:09 ` [PATCH 10/11] x86/smp: Bring up secondary CPUs in parallel David Woodhouse
2021-12-09 15:09 ` [PATCH 11/11] x86/kvm: Silence per-cpu pr_info noise about KVM clocks and steal time David Woodhouse
2021-12-09 17:39 ` Paolo Bonzini
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