From: Yicong Yang <yangyicong@hisilicon.com> driver inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IBZQQR ---------------------------------------------------------------------- Currently if architectures want to support HOTPLUG_SMT they need to provide a topology_is_primary_thread() telling the framework which thread in the SMT cannot offline. However arm64 doesn't have a restriction on which thread in the SMT cannot offline, a simplest choice is that just make 1st thread as the "primary" thread. So just make this as the default implementation in the framework and let architectures like x86 that have special primary thread to override this function (which they've already done). There's no need to provide a stub function if !CONFIG_SMP or !CONFIG_HOTPLUG_SMT. In such case the testing CPU is already the 1st CPU in the SMT so it's always the primary thread. Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Reviewed-by: Pierre Gondois <pierre.gondois@arm.com> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Reviewed-by: Hongye Lin <linhongye@h-partners.com> Signed-off-by: Hongye Lin <linhongye@h-partners.com> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> --- arch/powerpc/include/asm/topology.h | 1 + arch/x86/include/asm/topology.h | 3 ++- include/linux/topology.h | 24 ++++++++++++++++++++++++ 3 files changed, 27 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h index 16bacfe8c7a2..da15b5efe807 100644 --- a/arch/powerpc/include/asm/topology.h +++ b/arch/powerpc/include/asm/topology.h @@ -152,6 +152,7 @@ static inline bool topology_is_primary_thread(unsigned int cpu) { return cpu == cpu_first_thread_sibling(cpu); } +#define topology_is_primary_thread topology_is_primary_thread static inline bool topology_smt_thread_allowed(unsigned int cpu) { diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index 3235ba1e5b06..61f6350b4ed1 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -153,6 +153,8 @@ static inline bool topology_is_primary_thread(unsigned int cpu) { return cpumask_test_cpu(cpu, cpu_primary_thread_mask); } +#define topology_is_primary_thread topology_is_primary_thread + #else /* CONFIG_SMP */ #define topology_max_packages() (1) static inline int @@ -162,7 +164,6 @@ topology_update_die_map(unsigned int dieid, unsigned int cpu) { return 0; } static inline int topology_phys_to_logical_pkg(unsigned int pkg) { return 0; } static inline int topology_max_die_per_package(void) { return 1; } static inline int topology_max_smt_threads(void) { return 1; } -static inline bool topology_is_primary_thread(unsigned int cpu) { return true; } #endif /* !CONFIG_SMP */ static inline void arch_fix_phys_package_id(int num, u32 slot) diff --git a/include/linux/topology.h b/include/linux/topology.h index a2f15fd0e527..44465c56cbc1 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -241,6 +241,30 @@ static inline const struct cpumask *cpu_smt_mask(int cpu) } #endif +#ifndef topology_is_primary_thread + +#define topology_is_primary_thread topology_is_primary_thread + +static inline bool topology_is_primary_thread(unsigned int cpu) +{ + /* + * When disabling SMT the primary thread of the SMT will remain + * enabled/active. Architectures do have a special primary thread + * (e.g. x86) needs to override this function. Otherwise can make + * the first thread in the SMT as the primary thread. + * + * The sibling cpumask of an offline CPU contains always the CPU + * itself for architectures using the implementation of + * CONFIG_GENERIC_ARCH_TOPOLOGY for building their topology. + * Other architectures not using CONFIG_GENERIC_ARCH_TOPOLOGY for + * building their topology have to check whether to use this default + * implementation or to override it. + */ + return cpu == cpumask_first(topology_sibling_cpumask(cpu)); +} + +#endif + static inline const struct cpumask *cpu_cpu_mask(int cpu) { return cpumask_of_node(cpu_to_node(cpu)); -- 2.33.0