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| author |   Vitaly Kuznetsov <vkuznets@redhat.com> | 2019-09-16 18:22:56 +0200 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2019-09-24 13:37:28 +0200 |
| commit | e1572f1d08be57a5412a464cff0712a23cd0b73e (patch) | |
| tree | d1ee6d7671cd371c765778c9a73777a823dfe848 | |
| parent | KVM: hyperv: Fix Direct Synthetic timers assert an interrupt w/o lapic_in_kernel (diff) | |
| download | linux-dev-e1572f1d08be57a5412a464cff0712a23cd0b73e.tar.xz linux-dev-e1572f1d08be57a5412a464cff0712a23cd0b73e.zip | |
cpu/SMT: create and export cpu_smt_possible()
KVM needs to know if SMT is theoretically possible, this means it is
supported and not forcefully disabled ('nosmt=force'). Create and
export cpu_smt_possible() answering this question.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | include/linux/cpu.h | 2 | ||||
| -rw-r--r-- | kernel/cpu.c | 11 |
2 files changed, 11 insertions, 2 deletions
diff --git a/include/linux/cpu.h b/include/linux/cpu.h index 88dc0c653925..d0633ebdaa9c 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -201,12 +201,14 @@ enum cpuhp_smt_control { extern enum cpuhp_smt_control cpu_smt_control; extern void cpu_smt_disable(bool force); extern void cpu_smt_check_topology(void); +extern bool cpu_smt_possible(void); extern int cpuhp_smt_enable(void); extern int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval); #else # define cpu_smt_control (CPU_SMT_NOT_IMPLEMENTED) static inline void cpu_smt_disable(bool force) { } static inline void cpu_smt_check_topology(void) { } +static inline bool cpu_smt_possible(void) { return false; } static inline int cpuhp_smt_enable(void) { return 0; } static inline int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) { return 0; } #endif diff --git a/kernel/cpu.c b/kernel/cpu.c index e1967e9eddc2..fc28e17940e0 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -392,8 +392,7 @@ enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED; void __init cpu_smt_disable(bool force) { - if (cpu_smt_control == CPU_SMT_FORCE_DISABLED || - cpu_smt_control == CPU_SMT_NOT_SUPPORTED) + if (!cpu_smt_possible()) return; if (force) { @@ -438,6 +437,14 @@ static inline bool cpu_smt_allowed(unsigned int cpu) */ return !cpumask_test_cpu(cpu, &cpus_booted_once_mask); } + +/* Returns true if SMT is not supported of forcefully (irreversibly) disabled */ +bool cpu_smt_possible(void) +{ + return cpu_smt_control != CPU_SMT_FORCE_DISABLED && + cpu_smt_control != CPU_SMT_NOT_SUPPORTED; +} +EXPORT_SYMBOL_GPL(cpu_smt_possible); #else static inline bool cpu_smt_allowed(unsigned int cpu) { return true; } #endif |