From: Nadav Amit Date: Sat, 20 Feb 2021 23:17:08 +0000 (-0800) Subject: x86/mm/tlb: Privatize cpu_tlbstate X-Git-Tag: accepted/tizen/unified/20230118.172025~7336^2~6 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=2f4305b19fe6a2a261d76c21856c5598f7d878fe;p=platform%2Fkernel%2Flinux-rpi.git x86/mm/tlb: Privatize cpu_tlbstate cpu_tlbstate is mostly private and only the variable is_lazy is shared. This causes some false-sharing when TLB flushes are performed. Break cpu_tlbstate intro cpu_tlbstate and cpu_tlbstate_shared, and mark each one accordingly. Signed-off-by: Nadav Amit Signed-off-by: Ingo Molnar Reviewed-by: Dave Hansen Link: https://lore.kernel.org/r/20210220231712.2475218-6-namit@vmware.com --- diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 3c6681d..fa952ea 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -90,23 +90,6 @@ 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; - - /* * If set we changed the page tables in such a way that we * needed an invalidation of all contexts (aka. PCIDs / ASIDs). * This tells us to go invalidate all the non-loaded ctxs[] @@ -151,7 +134,27 @@ struct tlb_state { */ struct tlb_context ctxs[TLB_NR_DYN_ASIDS]; }; -DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate); +DECLARE_PER_CPU_ALIGNED(struct tlb_state, cpu_tlbstate); + +struct tlb_state_shared { + /* + * 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; +}; +DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state_shared, cpu_tlbstate_shared); bool nmi_uaccess_okay(void); #define nmi_uaccess_okay nmi_uaccess_okay diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 8d778e4..94649f8 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -813,7 +813,7 @@ static inline temp_mm_state_t use_temporary_mm(struct mm_struct *mm) * with a stale address space WITHOUT being in lazy mode after * restoring the previous mm. */ - if (this_cpu_read(cpu_tlbstate.is_lazy)) + if (this_cpu_read(cpu_tlbstate_shared.is_lazy)) leave_mm(smp_processor_id()); temp_state.mm = this_cpu_read(cpu_tlbstate.loaded_mm); diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index dd694fb9..ed2e367 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -1017,7 +1017,7 @@ void __init zone_sizes_init(void) free_area_init(max_zone_pfns); } -__visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate) = { +__visible DEFINE_PER_CPU_ALIGNED(struct tlb_state, cpu_tlbstate) = { .loaded_mm = &init_mm, .next_asid = 1, .cr4 = ~0UL, /* fail hard if we screw up cr4 shadow initialization */ diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 8db87cd..345a0af 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -300,7 +300,7 @@ void leave_mm(int cpu) return; /* Warn if we're not lazy. */ - WARN_ON(!this_cpu_read(cpu_tlbstate.is_lazy)); + WARN_ON(!this_cpu_read(cpu_tlbstate_shared.is_lazy)); switch_mm(NULL, &init_mm, NULL); } @@ -424,7 +424,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, { struct mm_struct *real_prev = this_cpu_read(cpu_tlbstate.loaded_mm); u16 prev_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid); - bool was_lazy = this_cpu_read(cpu_tlbstate.is_lazy); + bool was_lazy = this_cpu_read(cpu_tlbstate_shared.is_lazy); unsigned cpu = smp_processor_id(); u64 next_tlb_gen; bool need_flush; @@ -469,7 +469,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, __flush_tlb_all(); } #endif - this_cpu_write(cpu_tlbstate.is_lazy, false); + this_cpu_write(cpu_tlbstate_shared.is_lazy, false); /* * The membarrier system call requires a full memory barrier and @@ -490,7 +490,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, /* * Even in lazy TLB mode, the CPU should stay set in the * mm_cpumask. The TLB shootdown code can figure out from - * cpu_tlbstate.is_lazy whether or not to send an IPI. + * cpu_tlbstate_shared.is_lazy whether or not to send an IPI. */ if (WARN_ON_ONCE(real_prev != &init_mm && !cpumask_test_cpu(cpu, mm_cpumask(next)))) @@ -598,7 +598,7 @@ void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) if (this_cpu_read(cpu_tlbstate.loaded_mm) == &init_mm) return; - this_cpu_write(cpu_tlbstate.is_lazy, true); + this_cpu_write(cpu_tlbstate_shared.is_lazy, true); } /* @@ -690,7 +690,7 @@ static void flush_tlb_func(void *info) VM_WARN_ON(this_cpu_read(cpu_tlbstate.ctxs[loaded_mm_asid].ctx_id) != loaded_mm->context.ctx_id); - if (this_cpu_read(cpu_tlbstate.is_lazy)) { + if (this_cpu_read(cpu_tlbstate_shared.is_lazy)) { /* * We're in lazy mode. We need to at least flush our * paging-structure cache to avoid speculatively reading @@ -790,11 +790,14 @@ done: static bool tlb_is_not_lazy(int cpu) { - return !per_cpu(cpu_tlbstate.is_lazy, cpu); + return !per_cpu(cpu_tlbstate_shared.is_lazy, cpu); } static DEFINE_PER_CPU(cpumask_t, flush_tlb_mask); +DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state_shared, cpu_tlbstate_shared); +EXPORT_PER_CPU_SYMBOL(cpu_tlbstate_shared); + STATIC_NOPV void native_flush_tlb_multi(const struct cpumask *cpumask, const struct flush_tlb_info *info) {