Messages in this thread Patch in this message | | | From | Tim Chen <> | Subject | [Patch v3 05/13] x86/smt: Create cpu_smt_enabled static key for SMT specific code | Date | Wed, 17 Oct 2018 10:59:33 -0700 |
| |
Create the cpu_smt_enabled static key to indicate if we are using SMT. SMT specific code paths are executed only when SMT code paths are enabled by this key.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> --- arch/x86/kernel/cpu/bugs.c | 2 +- arch/x86/kvm/vmx.c | 2 +- include/linux/cpu.h | 1 + kernel/cpu.c | 12 ++++++++++-- 4 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 6ed82ea..0338fa1 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -358,7 +358,7 @@ void arch_smt_update(void) mutex_lock(&spec_ctrl_mutex); mask = x86_spec_ctrl_base; - if (cpu_smt_control == CPU_SMT_ENABLED) + if (static_branch_likely(&cpu_smt_enabled)) mask |= SPEC_CTRL_STIBP; else mask &= ~SPEC_CTRL_STIBP; diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 533a327..8ec0ea3 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -11072,7 +11072,7 @@ static int vmx_vm_init(struct kvm *kvm) * Warn upon starting the first VM in a potentially * insecure environment. */ - if (cpu_smt_control == CPU_SMT_ENABLED) + if (static_branch_likely(&cpu_smt_enabled)) pr_warn_once(L1TF_MSG_SMT); if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_NEVER) pr_warn_once(L1TF_MSG_L1D); diff --git a/include/linux/cpu.h b/include/linux/cpu.h index 218df7f..b54f085 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -188,5 +188,6 @@ static inline void cpu_smt_disable(bool force) { } static inline void cpu_smt_check_topology_early(void) { } static inline void cpu_smt_check_topology(void) { } #endif +DECLARE_STATIC_KEY_TRUE(cpu_smt_enabled); #endif /* _LINUX_CPU_H_ */ diff --git a/kernel/cpu.c b/kernel/cpu.c index 3adecda..ad28afc 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -349,6 +349,8 @@ EXPORT_SYMBOL_GPL(cpu_hotplug_enable); #ifdef CONFIG_HOTPLUG_SMT enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED; EXPORT_SYMBOL_GPL(cpu_smt_control); +DEFINE_STATIC_KEY_TRUE(cpu_smt_enabled); +EXPORT_SYMBOL_GPL(cpu_smt_enabled); static bool cpu_smt_available __read_mostly; @@ -364,6 +366,7 @@ void __init cpu_smt_disable(bool force) } else { cpu_smt_control = CPU_SMT_DISABLED; } + static_branch_disable(&cpu_smt_enabled); } /* @@ -373,8 +376,10 @@ void __init cpu_smt_disable(bool force) */ void __init cpu_smt_check_topology_early(void) { - if (!topology_smt_supported()) + if (!topology_smt_supported()) { cpu_smt_control = CPU_SMT_NOT_SUPPORTED; + static_branch_disable(&cpu_smt_enabled); + } } /* @@ -386,8 +391,10 @@ void __init cpu_smt_check_topology_early(void) */ void __init cpu_smt_check_topology(void) { - if (!cpu_smt_available) + if (!cpu_smt_available) { cpu_smt_control = CPU_SMT_NOT_SUPPORTED; + static_branch_disable(&cpu_smt_enabled); + } } static int __init smt_cmdline_disable(char *str) @@ -2072,6 +2079,7 @@ static int cpuhp_smt_enable(void) cpu_maps_update_begin(); cpu_smt_control = CPU_SMT_ENABLED; + static_branch_enable(&cpu_smt_enabled); arch_smt_update(); for_each_present_cpu(cpu) { /* Skip online CPUs and CPUs on offline nodes */ -- 2.9.4
| |