Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull cpu hotplug fixes from Thomas Gleixner: "Two fixes for the cpu hotplug machinery: - Replace the overly clever 'SMT disabled by BIOS' detection logic as it breaks KVM scenarios and prevents speculation control updates when the Hyperthreads are brought online late after boot. - Remove a redundant invocation of the speculation control update function" * 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM x86/speculation: Remove redundant arch_smt_update() invocation
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Коммит
cc6810e36b
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@ -71,7 +71,7 @@ void __init check_bugs(void)
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* identify_boot_cpu() initialized SMT support information, let the
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* core code know.
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*/
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cpu_smt_check_topology_early();
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cpu_smt_check_topology();
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if (!IS_ENABLED(CONFIG_SMP)) {
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pr_info("CPU: ");
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@ -26,6 +26,7 @@
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#include <linux/mod_devicetable.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/sched/smt.h>
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#include <linux/slab.h>
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#include <linux/tboot.h>
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#include <linux/trace_events.h>
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@ -6823,7 +6824,7 @@ static int vmx_vm_init(struct kvm *kvm)
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* Warn upon starting the first VM in a potentially
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* insecure environment.
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*/
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if (cpu_smt_control == CPU_SMT_ENABLED)
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if (sched_smt_active())
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pr_warn_once(L1TF_MSG_SMT);
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if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_NEVER)
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pr_warn_once(L1TF_MSG_L1D);
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@ -180,12 +180,10 @@ enum cpuhp_smt_control {
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#if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_SMT)
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extern enum cpuhp_smt_control cpu_smt_control;
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extern void cpu_smt_disable(bool force);
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extern void cpu_smt_check_topology_early(void);
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extern void cpu_smt_check_topology(void);
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#else
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# define cpu_smt_control (CPU_SMT_ENABLED)
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static inline void cpu_smt_disable(bool force) { }
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static inline void cpu_smt_check_topology_early(void) { }
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static inline void cpu_smt_check_topology(void) { }
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#endif
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38
kernel/cpu.c
38
kernel/cpu.c
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@ -376,9 +376,6 @@ void __weak arch_smt_update(void) { }
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#ifdef CONFIG_HOTPLUG_SMT
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enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED;
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EXPORT_SYMBOL_GPL(cpu_smt_control);
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static bool cpu_smt_available __read_mostly;
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void __init cpu_smt_disable(bool force)
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{
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@ -397,25 +394,11 @@ void __init cpu_smt_disable(bool force)
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/*
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* The decision whether SMT is supported can only be done after the full
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* CPU identification. Called from architecture code before non boot CPUs
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* are brought up.
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*/
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void __init cpu_smt_check_topology_early(void)
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{
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if (!topology_smt_supported())
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cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
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}
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/*
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* If SMT was disabled by BIOS, detect it here, after the CPUs have been
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* brought online. This ensures the smt/l1tf sysfs entries are consistent
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* with reality. cpu_smt_available is set to true during the bringup of non
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* boot CPUs when a SMT sibling is detected. Note, this may overwrite
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* cpu_smt_control's previous setting.
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* CPU identification. Called from architecture code.
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*/
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void __init cpu_smt_check_topology(void)
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{
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if (!cpu_smt_available)
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if (!topology_smt_supported())
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cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
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}
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@ -428,18 +411,10 @@ early_param("nosmt", smt_cmdline_disable);
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static inline bool cpu_smt_allowed(unsigned int cpu)
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{
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if (topology_is_primary_thread(cpu))
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if (cpu_smt_control == CPU_SMT_ENABLED)
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return true;
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/*
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* If the CPU is not a 'primary' thread and the booted_once bit is
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* set then the processor has SMT support. Store this information
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* for the late check of SMT support in cpu_smt_check_topology().
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*/
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if (per_cpu(cpuhp_state, cpu).booted_once)
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cpu_smt_available = true;
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if (cpu_smt_control == CPU_SMT_ENABLED)
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if (topology_is_primary_thread(cpu))
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return true;
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/*
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@ -2090,10 +2065,8 @@ static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
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*/
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cpuhp_offline_cpu_device(cpu);
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}
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if (!ret) {
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if (!ret)
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cpu_smt_control = ctrlval;
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arch_smt_update();
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}
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cpu_maps_update_done();
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return ret;
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}
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@ -2104,7 +2077,6 @@ static int cpuhp_smt_enable(void)
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cpu_maps_update_begin();
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cpu_smt_control = CPU_SMT_ENABLED;
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arch_smt_update();
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for_each_present_cpu(cpu) {
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/* Skip online CPUs and CPUs on offline nodes */
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if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
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@ -5980,6 +5980,7 @@ static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p
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#ifdef CONFIG_SCHED_SMT
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DEFINE_STATIC_KEY_FALSE(sched_smt_present);
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EXPORT_SYMBOL_GPL(sched_smt_present);
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static inline void set_idle_cores(int cpu, int val)
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{
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@ -584,8 +584,6 @@ void __init smp_init(void)
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num_nodes, (num_nodes > 1 ? "s" : ""),
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num_cpus, (num_cpus > 1 ? "s" : ""));
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/* Final decision about SMT support */
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cpu_smt_check_topology();
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/* Any cleanup work */
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smp_cpus_done(setup_max_cpus);
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}
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