diff options
Diffstat (limited to 'arch/x86/include/asm/tlbflush.h')
| -rw-r--r-- | arch/x86/include/asm/tlbflush.h | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 4893abf7f74f..d362161d3291 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -83,6 +83,13 @@ static inline u64 inc_mm_tlb_gen(struct mm_struct *mm) #endif /* + * If tlb_use_lazy_mode is true, then we try to avoid switching CR3 to point + * to init_mm when we switch to a kernel thread (e.g. the idle thread). If + * it's false, then we immediately switch CR3 when entering a kernel thread. + */ +DECLARE_STATIC_KEY_TRUE(tlb_use_lazy_mode); + +/* * 6 because 6 should be plenty and struct tlb_state will fit in * two cache lines. */ @@ -105,6 +112,23 @@ struct tlb_state { u16 next_asid; /* + * We can be in one of several states: + * + * - Actively using an mm. Our CPU's bit will be set in + * mm_cpumask(loaded_mm) and is_lazy == false; + * + * - Not using a real mm. loaded_mm == &init_mm. Our CPU's bit + * will not be set in mm_cpumask(&init_mm) and is_lazy == false. + * + * - Lazily using a real mm. loaded_mm != &init_mm, our bit + * is set in mm_cpumask(loaded_mm), but is_lazy == true. + * We're heuristically guessing that the CR3 load we + * skipped more than makes up for the overhead added by + * lazy mode. + */ + bool is_lazy; + + /* * Access to this CR4 shadow and to H/W CR4 is protected by * disabling interrupts when modifying either one. */ |