x86/smpboot: Serialize topology updates for secondary bringup

If we bring up secondaries in parallel they might get confused unless we
impose some ordering here:

[    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)

Do the full topology update in smp_store_cpu_info() under a spinlock
to ensure that things remain consistent.

[Usama Arif: fixed rebase conflict]
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 33c0d5fd8af6f5344736e77754697cc3edec2517..b4b29e052b6ee669c0ece43119e5bd02e70c33ec 100644 (file)
--- 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 458c891a82736549469c2c09b38848f18634412a..4bccbd949a9937998c6eec89d45b6374950b6b1a 100644 (file)
--- 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 9cfca3d7d0e207c518b7cadf192a0f1337f790d6..cf1a4eff7a7658399098e585ca0843a5d3bee678 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1766,7 +1766,7 @@ 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();
@@ -1777,8 +1777,6 @@ 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
@@ -1969,7 +1967,7 @@ 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 e3e7e4705a6c89265fdb7bb12c95760eeaebd6fa..f53a060a899b7854962b3ff25ff3aaad3b1ed41f 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -182,16 +182,12 @@ 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();
 
@@ -246,6 +242,12 @@ static void notrace start_secondary(void *unused)
         * smp_callout_mask to release them.
         */
        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();
 
@@ -354,7 +356,7 @@ 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;
 
@@ -377,7 +379,7 @@ found:
  * @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;
 
@@ -408,25 +410,7 @@ 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)
@@ -632,7 +616,7 @@ 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;
@@ -711,6 +695,37 @@ 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 6175f2c5c8224b212f332f63a7f7fb8c6401bf4c..09f94f9406895fde453c73b69b8f23299d32ffea 100644 (file)
--- 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();