diff options
Diffstat (limited to 'arch/x86/mm/tlb.c')
| -rw-r--r-- | arch/x86/mm/tlb.c | 64 |
1 files changed, 6 insertions, 58 deletions
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 658bf0090565..0f3d0cea4d00 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -30,7 +30,6 @@ atomic64_t last_mm_ctx_id = ATOMIC64_INIT(1); -DEFINE_STATIC_KEY_TRUE(tlb_use_lazy_mode); static void choose_new_asid(struct mm_struct *next, u64 next_tlb_gen, u16 *new_asid, bool *need_flush) @@ -147,8 +146,8 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, this_cpu_write(cpu_tlbstate.is_lazy, false); if (real_prev == next) { - VM_BUG_ON(this_cpu_read(cpu_tlbstate.ctxs[prev_asid].ctx_id) != - next->context.ctx_id); + VM_WARN_ON(this_cpu_read(cpu_tlbstate.ctxs[prev_asid].ctx_id) != + next->context.ctx_id); /* * We don't currently support having a real mm loaded without @@ -213,6 +212,9 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, } /* + * Please ignore the name of this function. It should be called + * switch_to_kernel_thread(). + * * enter_lazy_tlb() is a hint from the scheduler that we are entering a * kernel thread or other context without an mm. Acceptable implementations * include doing nothing whatsoever, switching to init_mm, or various clever @@ -227,7 +229,7 @@ void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) if (this_cpu_read(cpu_tlbstate.loaded_mm) == &init_mm) return; - if (static_branch_unlikely(&tlb_use_lazy_mode)) { + if (tlb_defer_switch_to_init_mm()) { /* * There's a significant optimization that may be possible * here. We have accurate enough TLB flush tracking that we @@ -626,57 +628,3 @@ static int __init create_tlb_single_page_flush_ceiling(void) return 0; } late_initcall(create_tlb_single_page_flush_ceiling); - -static ssize_t tlblazy_read_file(struct file *file, char __user *user_buf, - size_t count, loff_t *ppos) -{ - char buf[2]; - - buf[0] = static_branch_likely(&tlb_use_lazy_mode) ? '1' : '0'; - buf[1] = '\n'; - - return simple_read_from_buffer(user_buf, count, ppos, buf, 2); -} - -static ssize_t tlblazy_write_file(struct file *file, - const char __user *user_buf, size_t count, loff_t *ppos) -{ - bool val; - - if (kstrtobool_from_user(user_buf, count, &val)) - return -EINVAL; - - if (val) - static_branch_enable(&tlb_use_lazy_mode); - else - static_branch_disable(&tlb_use_lazy_mode); - - return count; -} - -static const struct file_operations fops_tlblazy = { - .read = tlblazy_read_file, - .write = tlblazy_write_file, - .llseek = default_llseek, -}; - -static int __init init_tlb_use_lazy_mode(void) -{ - if (boot_cpu_has(X86_FEATURE_PCID)) { - /* - * Heuristic: with PCID on, switching to and from - * init_mm is reasonably fast, but remote flush IPIs - * as expensive as ever, so turn off lazy TLB mode. - * - * We can't do this in setup_pcid() because static keys - * haven't been initialized yet, and it would blow up - * badly. - */ - static_branch_disable(&tlb_use_lazy_mode); - } - - debugfs_create_file("tlb_use_lazy_mode", S_IRUSR | S_IWUSR, - arch_debugfs_dir, NULL, &fops_tlblazy); - return 0; -} -late_initcall(init_tlb_use_lazy_mode); |