[PATCH v6 0/9] x86/tlb: Concurrent TLB flushes

[PATCH v6 0/9] x86/tlb: Concurrent TLB flushes

[Nadav Amit]

From: Nadav Amit <namit@vmware.com>

The series improves TLB shootdown by flushing the local TLB concurrently
with remote TLBs, overlapping the IPI delivery time with the local
flush. Performance numbers can be found in the previous version [1].

v5 was rebased on 5.11 (long time after v4), and had some bugs and
embarrassing build errors. Peter Zijlstra and Christoph Hellwig had some
comments as well. These issues were addressed (excluding one 82-chars
line that I left). Based on their feedback, an additional patch was also
added to reuse on_each_cpu_cond_mask() code and avoid unnecessary calls
by inlining.

KernelCI showed RCU stalls on arm64, which I could not figure out from
the kernel splat. If this issue persists, I would appreciate it someone
can assist in debugging or at least provide the output when running the
kernel with CONFIG_CSD_LOCK_WAIT_DEBUG=Y.

[1] https://lore.kernel.org/lkml/20190823224153.15223-1-namit@vmware.com/

v5 -> v6:
* Address build warnings due to rebase mistakes
* Reuse code from on_each_cpu_cond_mask() and inline [PeterZ]
* Fix some style issues [Hellwig]

v4 -> v5:
* Rebase on 5.11
* Move concurrent smp logic to smp_call_function_many_cond() 
* Remove SGI-UV patch which is not needed anymore

v3 -> v4:
* Merge flush_tlb_func_local and flush_tlb_func_remote() [Peter]
* Prevent preemption on_each_cpu(). It is not needed, but it prevents
  concerns. [Peter/tglx]
* Adding acked-, review-by tags

v2 -> v3:
* Open-code the remote/local-flush decision code [Andy]
* Fix hyper-v, Xen implementations [Andrew]
* Fix redundant TLB flushes.

v1 -> v2:
* Removing the patches that Thomas took [tglx]
* Adding hyper-v, Xen compile-tested implementations [Dave]
* Removing UV [Andy]
* Adding lazy optimization, removing inline keyword [Dave]
* Restructuring patch-set

RFCv2 -> v1:
* Fix comment on flush_tlb_multi [Juergen]
* Removing async invalidation optimizations [Andy]
* Adding KVM support [Paolo]

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm@vger.kernel.org
Cc: linux-hyperv@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Cc: x86@kernel.org
Cc: xen-devel@lists.xenproject.org

Nadav Amit (9):
  smp: Run functions concurrently in smp_call_function_many_cond()
  x86/mm/tlb: Unify flush_tlb_func_local() and flush_tlb_func_remote()
  x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy()
  x86/mm/tlb: Flush remote and local TLBs concurrently
  x86/mm/tlb: Privatize cpu_tlbstate
  x86/mm/tlb: Do not make is_lazy dirty for no reason
  cpumask: Mark functions as pure
  x86/mm/tlb: Remove unnecessary uses of the inline keyword
  smp: inline on_each_cpu_cond() and on_each_cpu()

 arch/x86/hyperv/mmu.c                 |  10 +-
 arch/x86/include/asm/paravirt.h       |   6 +-
 arch/x86/include/asm/paravirt_types.h |   4 +-
 arch/x86/include/asm/tlbflush.h       |  48 ++++---
 arch/x86/include/asm/trace/hyperv.h   |   2 +-
 arch/x86/kernel/alternative.c         |   2 +-
 arch/x86/kernel/kvm.c                 |  11 +-
 arch/x86/kernel/paravirt.c            |   2 +-
 arch/x86/mm/init.c                    |   2 +-
 arch/x86/mm/tlb.c                     | 176 +++++++++++++----------
 arch/x86/xen/mmu_pv.c                 |  11 +-
 include/linux/cpumask.h               |   6 +-
 include/linux/smp.h                   |  50 +++++--
 include/trace/events/xen.h            |   2 +-
 kernel/smp.c                          | 196 +++++++++++---------------
 15 files changed, 278 insertions(+), 250 deletions(-)

-- 
2.25.1

[PATCH v6 1/9] smp: Run functions concurrently in smp_call_function_many_cond()

[Nadav Amit]

From: Nadav Amit <namit@vmware.com>

Currently, on_each_cpu() and similar functions do not exploit the
potential of concurrency: the function is first executed remotely and
only then it is executed locally. Functions such as TLB flush can take
considerable time, so this provides an opportunity for performance
optimization.

To do so, modify smp_call_function_many_cond(), to allows the callers to
provide a function that should be executed (remotely/locally), and run
them concurrently. Keep other smp_call_function_many() semantic as it is
today for backward compatibility: the called function is not executed in
this case locally.

smp_call_function_many_cond() does not use the optimized version for a
single remote target that smp_call_function_single() implements. For
synchronous function call, smp_call_function_single() keeps a
call_single_data (which is used for synchronization) on the stack.
Interestingly, it seems that not using this optimization provides
greater performance improvements (greater speedup with a single remote
target than with multiple ones). Presumably, holding data structures
that are intended for synchronization on the stack can introduce
overheads due to TLB misses and false-sharing when the stack is used for
other purposes.

Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Nadav Amit <namit@vmware.com>

---
v5 -> v6:
* on_each_cpu_cond_mask() was missing preempt_disable/enable() [PeterZ]
* use multiplication instead of condition [PeterZ]
* assert preempt disabled on smp_call_function_many_cond()
* Break 80-char lines (Christoph)
---
 kernel/smp.c | 156 +++++++++++++++++++++++++++++----------------------
 1 file changed, 88 insertions(+), 68 deletions(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index aeb0adfa0606..c8a5a1facc1a 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -608,12 +608,28 @@ int smp_call_function_any(const struct cpumask *mask,
 }
 EXPORT_SYMBOL_GPL(smp_call_function_any);
 
+/*
+ * Flags to be used as scf_flags argument of smp_call_function_many_cond().
+ *
+ * %SCF_WAIT:		Wait until function execution is completed
+ * %SCF_RUN_LOCAL:	Run also locally if local cpu is set in cpumask
+ */
+#define SCF_WAIT	(1U << 0)
+#define SCF_RUN_LOCAL	(1U << 1)
+
 static void smp_call_function_many_cond(const struct cpumask *mask,
 					smp_call_func_t func, void *info,
-					bool wait, smp_cond_func_t cond_func)
+					unsigned int scf_flags,
+					smp_cond_func_t cond_func)
 {
+	int cpu, last_cpu, this_cpu = smp_processor_id();
 	struct call_function_data *cfd;
-	int cpu, next_cpu, this_cpu = smp_processor_id();
+	bool wait = scf_flags & SCF_WAIT;
+	bool run_remote = false;
+	bool run_local = false;
+	int nr_cpus = 0;
+
+	lockdep_assert_preemption_disabled();
 
 	/*
 	 * Can deadlock when called with interrupts disabled.
@@ -621,8 +637,9 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 	 * send smp call function interrupt to this cpu and as such deadlocks
 	 * can't happen.
 	 */
-	WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
-		     && !oops_in_progress && !early_boot_irqs_disabled);
+	if (cpu_online(this_cpu) && !oops_in_progress &&
+	    !early_boot_irqs_disabled)
+		lockdep_assert_irqs_enabled();
 
 	/*
 	 * When @wait we can deadlock when we interrupt between llist_add() and
@@ -632,60 +649,65 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 	 */
 	WARN_ON_ONCE(!in_task());
 
-	/* Try to fastpath.  So, what's a CPU they want? Ignoring this one. */
+	/* Check if we need local execution. */
+	if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(this_cpu, mask))
+		run_local = true;
+
+	/* Check if we need remote execution, i.e., any CPU excluding this one. */
 	cpu = cpumask_first_and(mask, cpu_online_mask);
 	if (cpu == this_cpu)
 		cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
+	if (cpu < nr_cpu_ids)
+		run_remote = true;
 
-	/* No online cpus?  We're done. */
-	if (cpu >= nr_cpu_ids)
-		return;
-
-	/* Do we have another CPU which isn't us? */
-	next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
-	if (next_cpu == this_cpu)
-		next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
-
-	/* Fastpath: do that cpu by itself. */
-	if (next_cpu >= nr_cpu_ids) {
-		if (!cond_func || cond_func(cpu, info))
-			smp_call_function_single(cpu, func, info, wait);
-		return;
-	}
-
-	cfd = this_cpu_ptr(&cfd_data);
+	if (run_remote) {
+		cfd = this_cpu_ptr(&cfd_data);
+		cpumask_and(cfd->cpumask, mask, cpu_online_mask);
+		__cpumask_clear_cpu(this_cpu, cfd->cpumask);
 
-	cpumask_and(cfd->cpumask, mask, cpu_online_mask);
-	__cpumask_clear_cpu(this_cpu, cfd->cpumask);
-
-	/* Some callers race with other cpus changing the passed mask */
-	if (unlikely(!cpumask_weight(cfd->cpumask)))
-		return;
+		cpumask_clear(cfd->cpumask_ipi);
+		for_each_cpu(cpu, cfd->cpumask) {
+			call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
 
-	cpumask_clear(cfd->cpumask_ipi);
-	for_each_cpu(cpu, cfd->cpumask) {
-		call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
+			if (cond_func && !cond_func(cpu, info))
+				continue;
 
-		if (cond_func && !cond_func(cpu, info))
-			continue;
-
-		csd_lock(csd);
-		if (wait)
-			csd->node.u_flags |= CSD_TYPE_SYNC;
-		csd->func = func;
-		csd->info = info;
+			csd_lock(csd);
+			if (wait)
+				csd->node.u_flags |= CSD_TYPE_SYNC;
+			csd->func = func;
+			csd->info = info;
 #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
-		csd->node.src = smp_processor_id();
-		csd->node.dst = cpu;
+			csd->node.src = smp_processor_id();
+			csd->node.dst = cpu;
 #endif
-		if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu)))
-			__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
+			if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) {
+				__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
+				nr_cpus++;
+				last_cpu = cpu;
+			}
+		}
+
+		/*
+		 * Choose the most efficient way to send an IPI. Note that the
+		 * number of CPUs might be zero due to concurrent changes to the
+		 * provided mask.
+		 */
+		if (nr_cpus == 1)
+			arch_send_call_function_single_ipi(last_cpu);
+		else if (likely(nr_cpus > 1))
+			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
 	}
 
-	/* Send a message to all CPUs in the map */
-	arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
+	if (run_local && (!cond_func || cond_func(this_cpu, info))) {
+		unsigned long flags;
 
-	if (wait) {
+		local_irq_save(flags);
+		func(info);
+		local_irq_restore(flags);
+	}
+
+	if (run_remote && wait) {
 		for_each_cpu(cpu, cfd->cpumask) {
 			call_single_data_t *csd;
 
@@ -696,12 +718,14 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 }
 
 /**
- * smp_call_function_many(): Run a function on a set of other CPUs.
+ * smp_call_function_many(): Run a function on a set of CPUs.
  * @mask: The set of cpus to run on (only runs on online subset).
  * @func: The function to run. This must be fast and non-blocking.
  * @info: An arbitrary pointer to pass to the function.
- * @wait: If true, wait (atomically) until function has completed
- *        on other CPUs.
+ * @flags: Bitmask that controls the operation. If %SCF_WAIT is set, wait
+ *        (atomically) until function has completed on other CPUs. If
+ *        %SCF_RUN_LOCAL is set, the function will also be run locally
+ *        if the local CPU is set in the @cpumask.
  *
  * If @wait is true, then returns once @func has returned.
  *
@@ -712,7 +736,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 void smp_call_function_many(const struct cpumask *mask,
 			    smp_call_func_t func, void *info, bool wait)
 {
-	smp_call_function_many_cond(mask, func, info, wait, NULL);
+	smp_call_function_many_cond(mask, func, info, wait * SCF_WAIT, NULL);
 }
 EXPORT_SYMBOL(smp_call_function_many);
 
@@ -860,16 +884,15 @@ EXPORT_SYMBOL(on_each_cpu);
 void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
 			void *info, bool wait)
 {
-	int cpu = get_cpu();
+	unsigned int scf_flags;
 
-	smp_call_function_many(mask, func, info, wait);
-	if (cpumask_test_cpu(cpu, mask)) {
-		unsigned long flags;
-		local_irq_save(flags);
-		func(info);
-		local_irq_restore(flags);
-	}
-	put_cpu();
+	scf_flags = SCF_RUN_LOCAL;
+	if (wait)
+		scf_flags |= SCF_WAIT;
+
+	preempt_disable();
+	smp_call_function_many_cond(mask, func, info, scf_flags, NULL);
+	preempt_enable();
 }
 EXPORT_SYMBOL(on_each_cpu_mask);
 
@@ -898,17 +921,14 @@ EXPORT_SYMBOL(on_each_cpu_mask);
 void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 			   void *info, bool wait, const struct cpumask *mask)
 {
-	int cpu = get_cpu();
+	unsigned int scf_flags = SCF_RUN_LOCAL;
 
-	smp_call_function_many_cond(mask, func, info, wait, cond_func);
-	if (cpumask_test_cpu(cpu, mask) && cond_func(cpu, info)) {
-		unsigned long flags;
+	if (wait)
+		scf_flags |= SCF_WAIT;
 
-		local_irq_save(flags);
-		func(info);
-		local_irq_restore(flags);
-	}
-	put_cpu();
+	preempt_disable();
+	smp_call_function_many_cond(mask, func, info, scf_flags, cond_func);
+	preempt_enable();
 }
 EXPORT_SYMBOL(on_each_cpu_cond_mask);
 
-- 
2.25.1

[PATCH v6 2/9] x86/mm/tlb: Unify flush_tlb_func_local() and flush_tlb_func_remote()

[Nadav Amit]

From: Nadav Amit <namit@vmware.com>

The unification of these two functions allows to use them in the updated
SMP infrastrucutre.

To do so, remove the reason argument from flush_tlb_func_local(), add
a member to struct tlb_flush_info that says which CPU initiated the
flush and act accordingly. Optimize the size of flush_tlb_info while we
are at it.

Unfortunately, this prevents us from using a constant tlb_flush_info for
arch_tlbbatch_flush(), but in a later stage we may be able to inline
tlb_flush_info into the IPI data, so it should not have an impact
eventually.

Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 arch/x86/include/asm/tlbflush.h |  5 +-
 arch/x86/mm/tlb.c               | 81 +++++++++++++++------------------
 2 files changed, 39 insertions(+), 47 deletions(-)

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 8c87a2e0b660..a7a598af116d 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -201,8 +201,9 @@ struct flush_tlb_info {
 	unsigned long		start;
 	unsigned long		end;
 	u64			new_tlb_gen;
-	unsigned int		stride_shift;
-	bool			freed_tables;
+	unsigned int		initiating_cpu;
+	u8			stride_shift;
+	u8			freed_tables;
 };
 
 void flush_tlb_local(void);
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 569ac1d57f55..bf12371db6c4 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -439,7 +439,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 	 * NB: leave_mm() calls us with prev == NULL and tsk == NULL.
 	 */
 
-	/* We don't want flush_tlb_func_* to run concurrently with us. */
+	/* We don't want flush_tlb_func() to run concurrently with us. */
 	if (IS_ENABLED(CONFIG_PROVE_LOCKING))
 		WARN_ON_ONCE(!irqs_disabled());
 
@@ -647,14 +647,13 @@ void initialize_tlbstate_and_flush(void)
 }
 
 /*
- * flush_tlb_func_common()'s memory ordering requirement is that any
+ * flush_tlb_func()'s memory ordering requirement is that any
  * TLB fills that happen after we flush the TLB are ordered after we
  * read active_mm's tlb_gen.  We don't need any explicit barriers
  * because all x86 flush operations are serializing and the
  * atomic64_read operation won't be reordered by the compiler.
  */
-static void flush_tlb_func_common(const struct flush_tlb_info *f,
-				  bool local, enum tlb_flush_reason reason)
+static void flush_tlb_func(void *info)
 {
 	/*
 	 * We have three different tlb_gen values in here.  They are:
@@ -665,14 +664,26 @@ static void flush_tlb_func_common(const struct flush_tlb_info *f,
 	 * - f->new_tlb_gen: the generation that the requester of the flush
 	 *                   wants us to catch up to.
 	 */
+	const struct flush_tlb_info *f = info;
 	struct mm_struct *loaded_mm = this_cpu_read(cpu_tlbstate.loaded_mm);
 	u32 loaded_mm_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid);
 	u64 mm_tlb_gen = atomic64_read(&loaded_mm->context.tlb_gen);
 	u64 local_tlb_gen = this_cpu_read(cpu_tlbstate.ctxs[loaded_mm_asid].tlb_gen);
+	bool local = smp_processor_id() == f->initiating_cpu;
+	unsigned long nr_invalidate = 0;
 
 	/* This code cannot presently handle being reentered. */
 	VM_WARN_ON(!irqs_disabled());
 
+	if (!local) {
+		inc_irq_stat(irq_tlb_count);
+		count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
+
+		/* Can only happen on remote CPUs */
+		if (f->mm && f->mm != loaded_mm)
+			return;
+	}
+
 	if (unlikely(loaded_mm == &init_mm))
 		return;
 
@@ -700,8 +711,7 @@ static void flush_tlb_func_common(const struct flush_tlb_info *f,
 		 * be handled can catch us all the way up, leaving no work for
 		 * the second flush.
 		 */
-		trace_tlb_flush(reason, 0);
-		return;
+		goto done;
 	}
 
 	WARN_ON_ONCE(local_tlb_gen > mm_tlb_gen);
@@ -748,46 +758,34 @@ static void flush_tlb_func_common(const struct flush_tlb_info *f,
 	    f->new_tlb_gen == local_tlb_gen + 1 &&
 	    f->new_tlb_gen == mm_tlb_gen) {
 		/* Partial flush */
-		unsigned long nr_invalidate = (f->end - f->start) >> f->stride_shift;
 		unsigned long addr = f->start;
 
+		nr_invalidate = (f->end - f->start) >> f->stride_shift;
+
 		while (addr < f->end) {
 			flush_tlb_one_user(addr);
 			addr += 1UL << f->stride_shift;
 		}
 		if (local)
 			count_vm_tlb_events(NR_TLB_LOCAL_FLUSH_ONE, nr_invalidate);
-		trace_tlb_flush(reason, nr_invalidate);
 	} else {
 		/* Full flush. */
+		nr_invalidate = TLB_FLUSH_ALL;
+
 		flush_tlb_local();
 		if (local)
 			count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
-		trace_tlb_flush(reason, TLB_FLUSH_ALL);
 	}
 
 	/* Both paths above update our state to mm_tlb_gen. */
 	this_cpu_write(cpu_tlbstate.ctxs[loaded_mm_asid].tlb_gen, mm_tlb_gen);
-}
-
-static void flush_tlb_func_local(const void *info, enum tlb_flush_reason reason)
-{
-	const struct flush_tlb_info *f = info;
-
-	flush_tlb_func_common(f, true, reason);
-}
 
-static void flush_tlb_func_remote(void *info)
-{
-	const struct flush_tlb_info *f = info;
-
-	inc_irq_stat(irq_tlb_count);
-
-	if (f->mm && f->mm != this_cpu_read(cpu_tlbstate.loaded_mm))
-		return;
-
-	count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
-	flush_tlb_func_common(f, false, TLB_REMOTE_SHOOTDOWN);
+	/* Tracing is done in a unified manner to reduce the code size */
+done:
+	trace_tlb_flush(!local ? TLB_REMOTE_SHOOTDOWN :
+				(f->mm == NULL) ? TLB_LOCAL_SHOOTDOWN :
+						  TLB_LOCAL_MM_SHOOTDOWN,
+			nr_invalidate);
 }
 
 static bool tlb_is_not_lazy(int cpu, void *data)
@@ -816,10 +814,10 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 	 * doing a speculative memory access.
 	 */
 	if (info->freed_tables)
-		smp_call_function_many(cpumask, flush_tlb_func_remote,
+		smp_call_function_many(cpumask, flush_tlb_func,
 			       (void *)info, 1);
 	else
-		on_each_cpu_cond_mask(tlb_is_not_lazy, flush_tlb_func_remote,
+		on_each_cpu_cond_mask(tlb_is_not_lazy, flush_tlb_func,
 				(void *)info, 1, cpumask);
 }
 
@@ -869,6 +867,7 @@ static inline struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
 	info->stride_shift	= stride_shift;
 	info->freed_tables	= freed_tables;
 	info->new_tlb_gen	= new_tlb_gen;
+	info->initiating_cpu	= smp_processor_id();
 
 	return info;
 }
@@ -908,7 +907,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 	if (mm == this_cpu_read(cpu_tlbstate.loaded_mm)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
-		flush_tlb_func_local(info, TLB_LOCAL_MM_SHOOTDOWN);
+		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
@@ -1119,34 +1118,26 @@ void __flush_tlb_all(void)
 }
 EXPORT_SYMBOL_GPL(__flush_tlb_all);
 
-/*
- * arch_tlbbatch_flush() performs a full TLB flush regardless of the active mm.
- * This means that the 'struct flush_tlb_info' that describes which mappings to
- * flush is actually fixed. We therefore set a single fixed struct and use it in
- * arch_tlbbatch_flush().
- */
-static const struct flush_tlb_info full_flush_tlb_info = {
-	.mm = NULL,
-	.start = 0,
-	.end = TLB_FLUSH_ALL,
-};
-
 void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
 {
+	struct flush_tlb_info *info;
+
 	int cpu = get_cpu();
 
+	info = get_flush_tlb_info(NULL, 0, TLB_FLUSH_ALL, 0, false, 0);
 	if (cpumask_test_cpu(cpu, &batch->cpumask)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
-		flush_tlb_func_local(&full_flush_tlb_info, TLB_LOCAL_SHOOTDOWN);
+		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
 	if (cpumask_any_but(&batch->cpumask, cpu) < nr_cpu_ids)
-		flush_tlb_others(&batch->cpumask, &full_flush_tlb_info);
+		flush_tlb_others(&batch->cpumask, info);
 
 	cpumask_clear(&batch->cpumask);
 
+	put_flush_tlb_info();
 	put_cpu();
 }
 
-- 
2.25.1

[PATCH v6 3/9] x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy()

[Nadav Amit]

From: Nadav Amit <namit@vmware.com>

Open-code on_each_cpu_cond_mask() in native_flush_tlb_others() to
optimize the code. Open-coding eliminates the need for the indirect branch
that is used to call is_lazy(), and in CPUs that are vulnerable to
Spectre v2, it eliminates the retpoline. In addition, it allows to use a
preallocated cpumask to compute the CPUs that should be.

This would later allow us not to adapt on_each_cpu_cond_mask() to
support local and remote functions.

Note that calling tlb_is_not_lazy() for every CPU that needs to be
flushed, as done in native_flush_tlb_multi() might look ugly, but it is
equivalent to what is currently done in on_each_cpu_cond_mask().
Actually, native_flush_tlb_multi() does it more efficiently since it
avoids using an indirect branch for the matter.

Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 arch/x86/mm/tlb.c | 37 ++++++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index bf12371db6c4..07b6701a540a 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -788,11 +788,13 @@ static void flush_tlb_func(void *info)
 			nr_invalidate);
 }
 
-static bool tlb_is_not_lazy(int cpu, void *data)
+static bool tlb_is_not_lazy(int cpu)
 {
 	return !per_cpu(cpu_tlbstate.is_lazy, cpu);
 }
 
+static DEFINE_PER_CPU(cpumask_t, flush_tlb_mask);
+
 STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 					 const struct flush_tlb_info *info)
 {
@@ -813,12 +815,37 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 	 * up on the new contents of what used to be page tables, while
 	 * doing a speculative memory access.
 	 */
-	if (info->freed_tables)
+	if (info->freed_tables) {
 		smp_call_function_many(cpumask, flush_tlb_func,
 			       (void *)info, 1);
-	else
-		on_each_cpu_cond_mask(tlb_is_not_lazy, flush_tlb_func,
-				(void *)info, 1, cpumask);
+	} else {
+		/*
+		 * Although we could have used on_each_cpu_cond_mask(),
+		 * open-coding it has performance advantages, as it eliminates
+		 * the need for indirect calls or retpolines. In addition, it
+		 * allows to use a designated cpumask for evaluating the
+		 * condition, instead of allocating one.
+		 *
+		 * This code works under the assumption that there are no nested
+		 * TLB flushes, an assumption that is already made in
+		 * flush_tlb_mm_range().
+		 *
+		 * cond_cpumask is logically a stack-local variable, but it is
+		 * more efficient to have it off the stack and not to allocate
+		 * it on demand. Preemption is disabled and this code is
+		 * non-reentrant.
+		 */
+		struct cpumask *cond_cpumask = this_cpu_ptr(&flush_tlb_mask);
+		int cpu;
+
+		cpumask_clear(cond_cpumask);
+
+		for_each_cpu(cpu, cpumask) {
+			if (tlb_is_not_lazy(cpu))
+				__cpumask_set_cpu(cpu, cond_cpumask);
+		}
+		smp_call_function_many(cond_cpumask, flush_tlb_func, (void *)info, 1);
+	}
 }
 
 void flush_tlb_others(const struct cpumask *cpumask,
-- 
2.25.1

[PATCH v6 4/9] x86/mm/tlb: Flush remote and local TLBs concurrently

[Nadav Amit]

From: Nadav Amit <namit@vmware.com>

To improve TLB shootdown performance, flush the remote and local TLBs
concurrently. Introduce flush_tlb_multi() that does so. Introduce
paravirtual versions of flush_tlb_multi() for KVM, Xen and hyper-v (Xen
and hyper-v are only compile-tested).

While the updated smp infrastructure is capable of running a function on
a single local core, it is not optimized for this case. The multiple
function calls and the indirect branch introduce some overhead, and
might make local TLB flushes slower than they were before the recent
changes.

Before calling the SMP infrastructure, check if only a local TLB flush
is needed to restore the lost performance in this common case. This
requires to check mm_cpumask() one more time, but unless this mask is
updated very frequently, this should impact performance negatively.

Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: Juergen Gross <jgross@suse.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: linux-hyperv@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Cc: kvm@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Reviewed-by: Michael Kelley <mikelley@microsoft.com> # Hyper-v parts
Reviewed-by: Juergen Gross <jgross@suse.com> # Xen and paravirt parts
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>

---
v5->v6:
* Use on_each_cpu_mask() instead of on_each_cpu_cond_mask() [PeterZ]
* Use cond_cpumask when needed instead of cpumask
* Rename remaining instance of native_flush_tlb_others()
---
 arch/x86/hyperv/mmu.c                 | 10 +++---
 arch/x86/include/asm/paravirt.h       |  6 ++--
 arch/x86/include/asm/paravirt_types.h |  4 +--
 arch/x86/include/asm/tlbflush.h       |  4 +--
 arch/x86/include/asm/trace/hyperv.h   |  2 +-
 arch/x86/kernel/kvm.c                 | 11 +++++--
 arch/x86/kernel/paravirt.c            |  2 +-
 arch/x86/mm/tlb.c                     | 46 +++++++++++++++++----------
 arch/x86/xen/mmu_pv.c                 | 11 +++----
 include/trace/events/xen.h            |  2 +-
 10 files changed, 57 insertions(+), 41 deletions(-)

diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c
index 2c87350c1fb0..681dba8de4f2 100644
--- a/arch/x86/hyperv/mmu.c
+++ b/arch/x86/hyperv/mmu.c
@@ -52,8 +52,8 @@ static inline int fill_gva_list(u64 gva_list[], int offset,
 	return gva_n - offset;
 }
 
-static void hyperv_flush_tlb_others(const struct cpumask *cpus,
-				    const struct flush_tlb_info *info)
+static void hyperv_flush_tlb_multi(const struct cpumask *cpus,
+				   const struct flush_tlb_info *info)
 {
 	int cpu, vcpu, gva_n, max_gvas;
 	struct hv_tlb_flush **flush_pcpu;
@@ -61,7 +61,7 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
 	u64 status = U64_MAX;
 	unsigned long flags;
 
-	trace_hyperv_mmu_flush_tlb_others(cpus, info);
+	trace_hyperv_mmu_flush_tlb_multi(cpus, info);
 
 	if (!hv_hypercall_pg)
 		goto do_native;
@@ -164,7 +164,7 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
 	if (!(status & HV_HYPERCALL_RESULT_MASK))
 		return;
 do_native:
-	native_flush_tlb_others(cpus, info);
+	native_flush_tlb_multi(cpus, info);
 }
 
 static u64 hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
@@ -239,6 +239,6 @@ void hyperv_setup_mmu_ops(void)
 		return;
 
 	pr_info("Using hypercall for remote TLB flush\n");
-	pv_ops.mmu.flush_tlb_others = hyperv_flush_tlb_others;
+	pv_ops.mmu.flush_tlb_multi = hyperv_flush_tlb_multi;
 	pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 }
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 4abf110e2243..45b55e3e0630 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -50,7 +50,7 @@ static inline void slow_down_io(void)
 void native_flush_tlb_local(void);
 void native_flush_tlb_global(void);
 void native_flush_tlb_one_user(unsigned long addr);
-void native_flush_tlb_others(const struct cpumask *cpumask,
+void native_flush_tlb_multi(const struct cpumask *cpumask,
 			     const struct flush_tlb_info *info);
 
 static inline void __flush_tlb_local(void)
@@ -68,10 +68,10 @@ static inline void __flush_tlb_one_user(unsigned long addr)
 	PVOP_VCALL1(mmu.flush_tlb_one_user, addr);
 }
 
-static inline void __flush_tlb_others(const struct cpumask *cpumask,
+static inline void __flush_tlb_multi(const struct cpumask *cpumask,
 				      const struct flush_tlb_info *info)
 {
-	PVOP_VCALL2(mmu.flush_tlb_others, cpumask, info);
+	PVOP_VCALL2(mmu.flush_tlb_multi, cpumask, info);
 }
 
 static inline void paravirt_tlb_remove_table(struct mmu_gather *tlb, void *table)
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index de87087d3bde..b7b35d5d58e7 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -188,8 +188,8 @@ struct pv_mmu_ops {
 	void (*flush_tlb_user)(void);
 	void (*flush_tlb_kernel)(void);
 	void (*flush_tlb_one_user)(unsigned long addr);
-	void (*flush_tlb_others)(const struct cpumask *cpus,
-				 const struct flush_tlb_info *info);
+	void (*flush_tlb_multi)(const struct cpumask *cpus,
+				const struct flush_tlb_info *info);
 
 	void (*tlb_remove_table)(struct mmu_gather *tlb, void *table);
 
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index a7a598af116d..3c6681def912 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -175,7 +175,7 @@ extern void initialize_tlbstate_and_flush(void);
  *  - flush_tlb_page(vma, vmaddr) flushes one page
  *  - flush_tlb_range(vma, start, end) flushes a range of pages
  *  - flush_tlb_kernel_range(start, end) flushes a range of kernel pages
- *  - flush_tlb_others(cpumask, info) flushes TLBs on other cpus
+ *  - flush_tlb_multi(cpumask, info) flushes TLBs on multiple cpus
  *
  * ..but the i386 has somewhat limited tlb flushing capabilities,
  * and page-granular flushes are available only on i486 and up.
@@ -209,7 +209,7 @@ struct flush_tlb_info {
 void flush_tlb_local(void);
 void flush_tlb_one_user(unsigned long addr);
 void flush_tlb_one_kernel(unsigned long addr);
-void flush_tlb_others(const struct cpumask *cpumask,
+void flush_tlb_multi(const struct cpumask *cpumask,
 		      const struct flush_tlb_info *info);
 
 #ifdef CONFIG_PARAVIRT
diff --git a/arch/x86/include/asm/trace/hyperv.h b/arch/x86/include/asm/trace/hyperv.h
index 4d705cb4d63b..a8e5a7a2b460 100644
--- a/arch/x86/include/asm/trace/hyperv.h
+++ b/arch/x86/include/asm/trace/hyperv.h
@@ -8,7 +8,7 @@
 
 #if IS_ENABLED(CONFIG_HYPERV)
 
-TRACE_EVENT(hyperv_mmu_flush_tlb_others,
+TRACE_EVENT(hyperv_mmu_flush_tlb_multi,
 	    TP_PROTO(const struct cpumask *cpus,
 		     const struct flush_tlb_info *info),
 	    TP_ARGS(cpus, info),
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5e78e01ca3b4..38ea9dee2456 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -613,7 +613,7 @@ static int kvm_cpu_down_prepare(unsigned int cpu)
 }
 #endif
 
-static void kvm_flush_tlb_others(const struct cpumask *cpumask,
+static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
 			const struct flush_tlb_info *info)
 {
 	u8 state;
@@ -627,6 +627,11 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask,
 	 * queue flush_on_enter for pre-empted vCPUs
 	 */
 	for_each_cpu(cpu, flushmask) {
+		/*
+		 * The local vCPU is never preempted, so we do not explicitly
+		 * skip check for local vCPU - it will never be cleared from
+		 * flushmask.
+		 */
 		src = &per_cpu(steal_time, cpu);
 		state = READ_ONCE(src->preempted);
 		if ((state & KVM_VCPU_PREEMPTED)) {
@@ -636,7 +641,7 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask,
 		}
 	}
 
-	native_flush_tlb_others(flushmask, info);
+	native_flush_tlb_multi(flushmask, info);
 }
 
 static void __init kvm_guest_init(void)
@@ -654,7 +659,7 @@ static void __init kvm_guest_init(void)
 	}
 
 	if (pv_tlb_flush_supported()) {
-		pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
+		pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
 		pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 		pr_info("KVM setup pv remote TLB flush\n");
 	}
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index c60222ab8ab9..197a12662155 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -330,7 +330,7 @@ struct paravirt_patch_template pv_ops = {
 	.mmu.flush_tlb_user	= native_flush_tlb_local,
 	.mmu.flush_tlb_kernel	= native_flush_tlb_global,
 	.mmu.flush_tlb_one_user	= native_flush_tlb_one_user,
-	.mmu.flush_tlb_others	= native_flush_tlb_others,
+	.mmu.flush_tlb_multi	= native_flush_tlb_multi,
 	.mmu.tlb_remove_table	=
 			(void (*)(struct mmu_gather *, void *))tlb_remove_page,
 
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 07b6701a540a..8db87cd92e6b 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -24,7 +24,7 @@
 # define __flush_tlb_local		native_flush_tlb_local
 # define __flush_tlb_global		native_flush_tlb_global
 # define __flush_tlb_one_user(addr)	native_flush_tlb_one_user(addr)
-# define __flush_tlb_others(msk, info)	native_flush_tlb_others(msk, info)
+# define __flush_tlb_multi(msk, info)	native_flush_tlb_multi(msk, info)
 #endif
 
 /*
@@ -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
-		 * from cpu_tlbstate.is_lazy whether or not to send an IPI.
+		 * cpu_tlbstate.is_lazy whether or not to send an IPI.
 		 */
 		if (WARN_ON_ONCE(real_prev != &init_mm &&
 				 !cpumask_test_cpu(cpu, mm_cpumask(next))))
@@ -697,7 +697,7 @@ static void flush_tlb_func(void *info)
 		 * garbage into our TLB.  Since switching to init_mm is barely
 		 * slower than a minimal flush, just switch to init_mm.
 		 *
-		 * This should be rare, with native_flush_tlb_others skipping
+		 * This should be rare, with native_flush_tlb_multi() skipping
 		 * IPIs to lazy TLB mode CPUs.
 		 */
 		switch_mm_irqs_off(NULL, &init_mm, NULL);
@@ -795,9 +795,14 @@ static bool tlb_is_not_lazy(int cpu)
 
 static DEFINE_PER_CPU(cpumask_t, flush_tlb_mask);
 
-STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
+STATIC_NOPV void native_flush_tlb_multi(const struct cpumask *cpumask,
 					 const struct flush_tlb_info *info)
 {
+	/*
+	 * Do accounting and tracing. Note that there are (and have always been)
+	 * cases in which a remote TLB flush will be traced, but eventually
+	 * would not happen.
+	 */
 	count_vm_tlb_event(NR_TLB_REMOTE_FLUSH);
 	if (info->end == TLB_FLUSH_ALL)
 		trace_tlb_flush(TLB_REMOTE_SEND_IPI, TLB_FLUSH_ALL);
@@ -816,8 +821,7 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 	 * doing a speculative memory access.
 	 */
 	if (info->freed_tables) {
-		smp_call_function_many(cpumask, flush_tlb_func,
-			       (void *)info, 1);
+		on_each_cpu_mask(cpumask, flush_tlb_func, (void *)info, true);
 	} else {
 		/*
 		 * Although we could have used on_each_cpu_cond_mask(),
@@ -844,14 +848,14 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 			if (tlb_is_not_lazy(cpu))
 				__cpumask_set_cpu(cpu, cond_cpumask);
 		}
-		smp_call_function_many(cond_cpumask, flush_tlb_func, (void *)info, 1);
+		on_each_cpu_mask(cond_cpumask, flush_tlb_func, (void *)info, true);
 	}
 }
 
-void flush_tlb_others(const struct cpumask *cpumask,
+void flush_tlb_multi(const struct cpumask *cpumask,
 		      const struct flush_tlb_info *info)
 {
-	__flush_tlb_others(cpumask, info);
+	__flush_tlb_multi(cpumask, info);
 }
 
 /*
@@ -931,16 +935,20 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 	info = get_flush_tlb_info(mm, start, end, stride_shift, freed_tables,
 				  new_tlb_gen);
 
-	if (mm == this_cpu_read(cpu_tlbstate.loaded_mm)) {
+	/*
+	 * flush_tlb_multi() is not optimized for the common case in which only
+	 * a local TLB flush is needed. Optimize this use-case by calling
+	 * flush_tlb_func_local() directly in this case.
+	 */
+	if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids) {
+		flush_tlb_multi(mm_cpumask(mm), info);
+	} else if (mm == this_cpu_read(cpu_tlbstate.loaded_mm)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
 		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
-	if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids)
-		flush_tlb_others(mm_cpumask(mm), info);
-
 	put_flush_tlb_info();
 	put_cpu();
 }
@@ -1152,16 +1160,20 @@ void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
 	int cpu = get_cpu();
 
 	info = get_flush_tlb_info(NULL, 0, TLB_FLUSH_ALL, 0, false, 0);
-	if (cpumask_test_cpu(cpu, &batch->cpumask)) {
+	/*
+	 * flush_tlb_multi() is not optimized for the common case in which only
+	 * a local TLB flush is needed. Optimize this use-case by calling
+	 * flush_tlb_func_local() directly in this case.
+	 */
+	if (cpumask_any_but(&batch->cpumask, cpu) < nr_cpu_ids) {
+		flush_tlb_multi(&batch->cpumask, info);
+	} else if (cpumask_test_cpu(cpu, &batch->cpumask)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
 		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
-	if (cpumask_any_but(&batch->cpumask, cpu) < nr_cpu_ids)
-		flush_tlb_others(&batch->cpumask, info);
-
 	cpumask_clear(&batch->cpumask);
 
 	put_flush_tlb_info();
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index cf2ade864c30..09b95c0e876e 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -1247,8 +1247,8 @@ static void xen_flush_tlb_one_user(unsigned long addr)
 	preempt_enable();
 }
 
-static void xen_flush_tlb_others(const struct cpumask *cpus,
-				 const struct flush_tlb_info *info)
+static void xen_flush_tlb_multi(const struct cpumask *cpus,
+				const struct flush_tlb_info *info)
 {
 	struct {
 		struct mmuext_op op;
@@ -1258,7 +1258,7 @@ static void xen_flush_tlb_others(const struct cpumask *cpus,
 	const size_t mc_entry_size = sizeof(args->op) +
 		sizeof(args->mask[0]) * BITS_TO_LONGS(num_possible_cpus());
 
-	trace_xen_mmu_flush_tlb_others(cpus, info->mm, info->start, info->end);
+	trace_xen_mmu_flush_tlb_multi(cpus, info->mm, info->start, info->end);
 
 	if (cpumask_empty(cpus))
 		return;		/* nothing to do */
@@ -1267,9 +1267,8 @@ static void xen_flush_tlb_others(const struct cpumask *cpus,
 	args = mcs.args;
 	args->op.arg2.vcpumask = to_cpumask(args->mask);
 
-	/* Remove us, and any offline CPUS. */
+	/* Remove any offline CPUs */
 	cpumask_and(to_cpumask(args->mask), cpus, cpu_online_mask);
-	cpumask_clear_cpu(smp_processor_id(), to_cpumask(args->mask));
 
 	args->op.cmd = MMUEXT_TLB_FLUSH_MULTI;
 	if (info->end != TLB_FLUSH_ALL &&
@@ -2086,7 +2085,7 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = {
 	.flush_tlb_user = xen_flush_tlb,
 	.flush_tlb_kernel = xen_flush_tlb,
 	.flush_tlb_one_user = xen_flush_tlb_one_user,
-	.flush_tlb_others = xen_flush_tlb_others,
+	.flush_tlb_multi = xen_flush_tlb_multi,
 	.tlb_remove_table = tlb_remove_table,
 
 	.pgd_alloc = xen_pgd_alloc,
diff --git a/include/trace/events/xen.h b/include/trace/events/xen.h
index 3b61b587e137..44a3f565264d 100644
--- a/include/trace/events/xen.h
+++ b/include/trace/events/xen.h
@@ -346,7 +346,7 @@ TRACE_EVENT(xen_mmu_flush_tlb_one_user,
 	    TP_printk("addr %lx", __entry->addr)
 	);
 
-TRACE_EVENT(xen_mmu_flush_tlb_others,
+TRACE_EVENT(xen_mmu_flush_tlb_multi,
 	    TP_PROTO(const struct cpumask *cpus, struct mm_struct *mm,
 		     unsigned long addr, unsigned long end),
 	    TP_ARGS(cpus, mm, addr, end),
-- 
2.25.1

[PATCH v6 5/9] x86/mm/tlb: Privatize cpu_tlbstate

[Nadav Amit]

From: Nadav Amit <namit@vmware.com>

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.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>

---
v5 -> v6:
* Fixed warning due to mismatch in
  {DEFINE|DECLARE}_PER_CPU_{SHARED_}ALIGNED
---
 arch/x86/include/asm/tlbflush.h | 39 ++++++++++++++++++---------------
 arch/x86/kernel/alternative.c   |  2 +-
 arch/x86/mm/init.c              |  2 +-
 arch/x86/mm/tlb.c               | 17 ++++++++------
 4 files changed, 33 insertions(+), 27 deletions(-)

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 3c6681def912..fa952eadbc2e 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -89,23 +89,6 @@ struct tlb_state {
 	u16 loaded_mm_asid;
 	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).
@@ -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 8d778e46725d..94649f86d653 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 dd694fb93916..ed2e36748758 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 8db87cd92e6b..345a0aff5de4 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 @@ static void flush_tlb_func(void *info)
 
 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)
 {
-- 
2.25.1

[PATCH v6 6/9] x86/mm/tlb: Do not make is_lazy dirty for no reason

[Nadav Amit]

From: Nadav Amit <namit@vmware.com>

Blindly writing to is_lazy for no reason, when the written value is
identical to the old value, makes the cacheline dirty for no reason.
Avoid making such writes to prevent cache coherency traffic for no
reason.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 arch/x86/mm/tlb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 345a0aff5de4..17ec4bfeee67 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -469,7 +469,8 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 		__flush_tlb_all();
 	}
 #endif
-	this_cpu_write(cpu_tlbstate_shared.is_lazy, false);
+	if (was_lazy)
+		this_cpu_write(cpu_tlbstate_shared.is_lazy, false);
 
 	/*
 	 * The membarrier system call requires a full memory barrier and
-- 
2.25.1

[PATCH v6 7/9] cpumask: Mark functions as pure

[Nadav Amit]

From: Nadav Amit <namit@vmware.com>

cpumask_next_and() and cpumask_any_but() are pure, and marking them as
such seems to generate different and presumably better code for
native_flush_tlb_multi().

Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 include/linux/cpumask.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 383684e30f12..c53364c4296d 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -235,7 +235,7 @@ static inline unsigned int cpumask_last(const struct cpumask *srcp)
 	return find_last_bit(cpumask_bits(srcp), nr_cpumask_bits);
 }
 
-unsigned int cpumask_next(int n, const struct cpumask *srcp);
+unsigned int __pure cpumask_next(int n, const struct cpumask *srcp);
 
 /**
  * cpumask_next_zero - get the next unset cpu in a cpumask
@@ -252,8 +252,8 @@ static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
 	return find_next_zero_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
 }
 
-int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
-int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
+int __pure cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
+int __pure cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
 unsigned int cpumask_local_spread(unsigned int i, int node);
 int cpumask_any_and_distribute(const struct cpumask *src1p,
 			       const struct cpumask *src2p);
-- 
2.25.1

[PATCH v6 8/9] x86/mm/tlb: Remove unnecessary uses of the inline keyword

[Nadav Amit]

From: Nadav Amit <namit@vmware.com>

The compiler is smart enough without these hints.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 arch/x86/mm/tlb.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 17ec4bfeee67..f4b162f273f5 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -316,7 +316,7 @@ void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 	local_irq_restore(flags);
 }
 
-static inline unsigned long mm_mangle_tif_spec_ib(struct task_struct *next)
+static unsigned long mm_mangle_tif_spec_ib(struct task_struct *next)
 {
 	unsigned long next_tif = task_thread_info(next)->flags;
 	unsigned long ibpb = (next_tif >> TIF_SPEC_IB) & LAST_USER_MM_IBPB;
@@ -880,7 +880,7 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct flush_tlb_info, flush_tlb_info);
 static DEFINE_PER_CPU(unsigned int, flush_tlb_info_idx);
 #endif
 
-static inline struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
+static struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
 			unsigned long start, unsigned long end,
 			unsigned int stride_shift, bool freed_tables,
 			u64 new_tlb_gen)
@@ -907,7 +907,7 @@ static inline struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
 	return info;
 }
 
-static inline void put_flush_tlb_info(void)
+static void put_flush_tlb_info(void)
 {
 #ifdef CONFIG_DEBUG_VM
 	/* Complete reentrency prevention checks */
-- 
2.25.1

[PATCH v6 9/9] smp: inline on_each_cpu_cond() and on_each_cpu()

[Nadav Amit]

From: Nadav Amit <namit@vmware.com>

Simplify the code and avoid having an additional function on the stack
by inlining on_each_cpu_cond() and on_each_cpu().

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 include/linux/smp.h | 50 ++++++++++++++++++++++++++++------------
 kernel/smp.c        | 56 ---------------------------------------------
 2 files changed, 36 insertions(+), 70 deletions(-)

diff --git a/include/linux/smp.h b/include/linux/smp.h
index 70c6f6284dcf..84a0b4828f66 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -50,30 +50,52 @@ extern unsigned int total_cpus;
 int smp_call_function_single(int cpuid, smp_call_func_t func, void *info,
 			     int wait);
 
+void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
+			   void *info, bool wait, const struct cpumask *mask);
+
+int smp_call_function_single_async(int cpu, call_single_data_t *csd);
+
 /*
  * Call a function on all processors
  */
-void on_each_cpu(smp_call_func_t func, void *info, int wait);
+static inline void on_each_cpu(smp_call_func_t func, void *info, int wait)
+{
+	on_each_cpu_cond_mask(NULL, func, info, wait, cpu_online_mask);
+}
 
-/*
- * Call a function on processors specified by mask, which might include
- * the local one.
+/**
+ * on_each_cpu_mask(): Run a function on processors specified by
+ * cpumask, which may include the local processor.
+ * @mask: The set of cpus to run on (only runs on online subset).
+ * @func: The function to run. This must be fast and non-blocking.
+ * @info: An arbitrary pointer to pass to the function.
+ * @wait: If true, wait (atomically) until function has completed
+ *        on other CPUs.
+ *
+ * If @wait is true, then returns once @func has returned.
+ *
+ * You must not call this function with disabled interrupts or from a
+ * hardware interrupt handler or from a bottom half handler.  The
+ * exception is that it may be used during early boot while
+ * early_boot_irqs_disabled is set.
  */
-void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
-		void *info, bool wait);
+static inline void on_each_cpu_mask(const struct cpumask *mask,
+				    smp_call_func_t func, void *info, bool wait)
+{
+	on_each_cpu_cond_mask(NULL, func, info, wait, mask);
+}
 
 /*
  * Call a function on each processor for which the supplied function
  * cond_func returns a positive value. This may include the local
- * processor.
+ * processor.  May be used during early boot while early_boot_irqs_disabled is
+ * set. Use local_irq_save/restore() instead of local_irq_disable/enable().
  */
-void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
-		      void *info, bool wait);
-
-void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
-			   void *info, bool wait, const struct cpumask *mask);
-
-int smp_call_function_single_async(int cpu, call_single_data_t *csd);
+static inline void on_each_cpu_cond(smp_cond_func_t cond_func,
+				    smp_call_func_t func, void *info, bool wait)
+{
+	on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
+}
 
 #ifdef CONFIG_SMP
 
diff --git a/kernel/smp.c b/kernel/smp.c
index c8a5a1facc1a..b6375d775e93 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -847,55 +847,6 @@ void __init smp_init(void)
 	smp_cpus_done(setup_max_cpus);
 }
 
-/*
- * Call a function on all processors.  May be used during early boot while
- * early_boot_irqs_disabled is set.  Use local_irq_save/restore() instead
- * of local_irq_disable/enable().
- */
-void on_each_cpu(smp_call_func_t func, void *info, int wait)
-{
-	unsigned long flags;
-
-	preempt_disable();
-	smp_call_function(func, info, wait);
-	local_irq_save(flags);
-	func(info);
-	local_irq_restore(flags);
-	preempt_enable();
-}
-EXPORT_SYMBOL(on_each_cpu);
-
-/**
- * on_each_cpu_mask(): Run a function on processors specified by
- * cpumask, which may include the local processor.
- * @mask: The set of cpus to run on (only runs on online subset).
- * @func: The function to run. This must be fast and non-blocking.
- * @info: An arbitrary pointer to pass to the function.
- * @wait: If true, wait (atomically) until function has completed
- *        on other CPUs.
- *
- * If @wait is true, then returns once @func has returned.
- *
- * You must not call this function with disabled interrupts or from a
- * hardware interrupt handler or from a bottom half handler.  The
- * exception is that it may be used during early boot while
- * early_boot_irqs_disabled is set.
- */
-void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
-			void *info, bool wait)
-{
-	unsigned int scf_flags;
-
-	scf_flags = SCF_RUN_LOCAL;
-	if (wait)
-		scf_flags |= SCF_WAIT;
-
-	preempt_disable();
-	smp_call_function_many_cond(mask, func, info, scf_flags, NULL);
-	preempt_enable();
-}
-EXPORT_SYMBOL(on_each_cpu_mask);
-
 /*
  * on_each_cpu_cond(): Call a function on each processor for which
  * the supplied function cond_func returns true, optionally waiting
@@ -932,13 +883,6 @@ void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 }
 EXPORT_SYMBOL(on_each_cpu_cond_mask);
 
-void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
-		      void *info, bool wait)
-{
-	on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
-}
-EXPORT_SYMBOL(on_each_cpu_cond);
-
 static void do_nothing(void *unused)
 {
 }
-- 
2.25.1

Re: [PATCH v6 1/9] smp: Run functions concurrently in smp_call_function_many_cond()

[Peter Zijlstra]

On Sat, Feb 20, 2021 at 03:17:04PM -0800, Nadav Amit wrote:
> +		/*
> +		 * Choose the most efficient way to send an IPI. Note that the
> +		 * number of CPUs might be zero due to concurrent changes to the
> +		 * provided mask.
> +		 */
> +		if (nr_cpus == 1)
> +			arch_send_call_function_single_ipi(last_cpu);
> +		else if (likely(nr_cpus > 1))
> +			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);

I just ran into conflicts with another patch set, and noticed that the
above should probably be:

		if (nr_cpus == 1)
			send_call_function_single_ipi(last_cpu);
		else if (likely(nr_cpus > 1))
			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);

Which will avoid the IPI when @last_cpu is idle.

Re: [PATCH v6 1/9] smp: Run functions concurrently in smp_call_function_many_cond()

[Nadav Amit]

> On Mar 1, 2021, at 9:10 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> 
> On Sat, Feb 20, 2021 at 03:17:04PM -0800, Nadav Amit wrote:
>> +		/*
>> +		 * Choose the most efficient way to send an IPI. Note that the
>> +		 * number of CPUs might be zero due to concurrent changes to the
>> +		 * provided mask.
>> +		 */
>> +		if (nr_cpus == 1)
>> +			arch_send_call_function_single_ipi(last_cpu);
>> +		else if (likely(nr_cpus > 1))
>> +			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
> 
> I just ran into conflicts with another patch set, and noticed that the
> above should probably be:
> 
> 		if (nr_cpus == 1)
> 			send_call_function_single_ipi(last_cpu);
> 		else if (likely(nr_cpus > 1))
> 			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
> 
> Which will avoid the IPI when @last_cpu is idle.

Good point. Makes one wonder whether all these inter-core communication
(through cpu_tlbstate.is_lazy, csd->node.llist and ti->flags) are
really necessary or can be combined.

Well, that’s for later I presume.

[PATCH] smp: Micro-optimize smp_call_function_many_cond()

[Ingo Molnar]

* Peter Zijlstra <peterz@infradead.org> wrote:

> On Sat, Feb 20, 2021 at 03:17:04PM -0800, Nadav Amit wrote:
> > +		/*
> > +		 * Choose the most efficient way to send an IPI. Note that the
> > +		 * number of CPUs might be zero due to concurrent changes to the
> > +		 * provided mask.
> > +		 */
> > +		if (nr_cpus == 1)
> > +			arch_send_call_function_single_ipi(last_cpu);
> > +		else if (likely(nr_cpus > 1))
> > +			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
> 
> I just ran into conflicts with another patch set, and noticed that the
> above should probably be:
> 
> 		if (nr_cpus == 1)
> 			send_call_function_single_ipi(last_cpu);
> 		else if (likely(nr_cpus > 1))
> 			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
> 
> Which will avoid the IPI when @last_cpu is idle.

I turned this into the additional patch below, on top of Nadav's series.

Thanks,

	Ingo

===============>
From: Ingo Molnar <mingo@kernel.org>
Date: Tue, 2 Mar 2021 08:02:43 +0100
Subject: [PATCH] smp: Micro-optimize smp_call_function_many_cond()

Call the generic send_call_function_single_ipi() function, which
will avoid the IPI when @last_cpu is idle.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
---
 kernel/smp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index b6375d775e93..af0d51da84a2 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -694,7 +694,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 		 * provided mask.
 		 */
 		if (nr_cpus == 1)
-			arch_send_call_function_single_ipi(last_cpu);
+			send_call_function_single_ipi(last_cpu);
 		else if (likely(nr_cpus > 1))
 			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
 	}

[tip: x86/mm] smp: Inline on_each_cpu_cond() and on_each_cpu()

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     28344ab0a282a5ab5e4d56bfbcb2b363f4c15447
Gitweb:        https://git.kernel.org/tip/28344ab0a282a5ab5e4d56bfbcb2b363f4c15447
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:12 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 02 Mar 2021 09:09:50 +01:00

smp: Inline on_each_cpu_cond() and on_each_cpu()

Simplify the code and avoid having an additional function on the stack
by inlining on_each_cpu_cond() and on_each_cpu().

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
[ Minor edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210220231712.2475218-10-namit@vmware.com
---
 include/linux/smp.h | 50 ++++++++++++++++++++++++++++-----------
 kernel/smp.c        | 56 +--------------------------------------------
 kernel/up.c         | 38 +------------------------------
 3 files changed, 37 insertions(+), 107 deletions(-)

diff --git a/include/linux/smp.h b/include/linux/smp.h
index 70c6f62..84a0b48 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -50,30 +50,52 @@ extern unsigned int total_cpus;
 int smp_call_function_single(int cpuid, smp_call_func_t func, void *info,
 			     int wait);
 
+void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
+			   void *info, bool wait, const struct cpumask *mask);
+
+int smp_call_function_single_async(int cpu, call_single_data_t *csd);
+
 /*
  * Call a function on all processors
  */
-void on_each_cpu(smp_call_func_t func, void *info, int wait);
+static inline void on_each_cpu(smp_call_func_t func, void *info, int wait)
+{
+	on_each_cpu_cond_mask(NULL, func, info, wait, cpu_online_mask);
+}
 
-/*
- * Call a function on processors specified by mask, which might include
- * the local one.
+/**
+ * on_each_cpu_mask(): Run a function on processors specified by
+ * cpumask, which may include the local processor.
+ * @mask: The set of cpus to run on (only runs on online subset).
+ * @func: The function to run. This must be fast and non-blocking.
+ * @info: An arbitrary pointer to pass to the function.
+ * @wait: If true, wait (atomically) until function has completed
+ *        on other CPUs.
+ *
+ * If @wait is true, then returns once @func has returned.
+ *
+ * You must not call this function with disabled interrupts or from a
+ * hardware interrupt handler or from a bottom half handler.  The
+ * exception is that it may be used during early boot while
+ * early_boot_irqs_disabled is set.
  */
-void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
-		void *info, bool wait);
+static inline void on_each_cpu_mask(const struct cpumask *mask,
+				    smp_call_func_t func, void *info, bool wait)
+{
+	on_each_cpu_cond_mask(NULL, func, info, wait, mask);
+}
 
 /*
  * Call a function on each processor for which the supplied function
  * cond_func returns a positive value. This may include the local
- * processor.
+ * processor.  May be used during early boot while early_boot_irqs_disabled is
+ * set. Use local_irq_save/restore() instead of local_irq_disable/enable().
  */
-void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
-		      void *info, bool wait);
-
-void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
-			   void *info, bool wait, const struct cpumask *mask);
-
-int smp_call_function_single_async(int cpu, call_single_data_t *csd);
+static inline void on_each_cpu_cond(smp_cond_func_t cond_func,
+				    smp_call_func_t func, void *info, bool wait)
+{
+	on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
+}
 
 #ifdef CONFIG_SMP
 
diff --git a/kernel/smp.c b/kernel/smp.c
index c8a5a1f..b6375d7 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -848,55 +848,6 @@ void __init smp_init(void)
 }
 
 /*
- * Call a function on all processors.  May be used during early boot while
- * early_boot_irqs_disabled is set.  Use local_irq_save/restore() instead
- * of local_irq_disable/enable().
- */
-void on_each_cpu(smp_call_func_t func, void *info, int wait)
-{
-	unsigned long flags;
-
-	preempt_disable();
-	smp_call_function(func, info, wait);
-	local_irq_save(flags);
-	func(info);
-	local_irq_restore(flags);
-	preempt_enable();
-}
-EXPORT_SYMBOL(on_each_cpu);
-
-/**
- * on_each_cpu_mask(): Run a function on processors specified by
- * cpumask, which may include the local processor.
- * @mask: The set of cpus to run on (only runs on online subset).
- * @func: The function to run. This must be fast and non-blocking.
- * @info: An arbitrary pointer to pass to the function.
- * @wait: If true, wait (atomically) until function has completed
- *        on other CPUs.
- *
- * If @wait is true, then returns once @func has returned.
- *
- * You must not call this function with disabled interrupts or from a
- * hardware interrupt handler or from a bottom half handler.  The
- * exception is that it may be used during early boot while
- * early_boot_irqs_disabled is set.
- */
-void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
-			void *info, bool wait)
-{
-	unsigned int scf_flags;
-
-	scf_flags = SCF_RUN_LOCAL;
-	if (wait)
-		scf_flags |= SCF_WAIT;
-
-	preempt_disable();
-	smp_call_function_many_cond(mask, func, info, scf_flags, NULL);
-	preempt_enable();
-}
-EXPORT_SYMBOL(on_each_cpu_mask);
-
-/*
  * on_each_cpu_cond(): Call a function on each processor for which
  * the supplied function cond_func returns true, optionally waiting
  * for all the required CPUs to finish. This may include the local
@@ -932,13 +883,6 @@ void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 }
 EXPORT_SYMBOL(on_each_cpu_cond_mask);
 
-void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
-		      void *info, bool wait)
-{
-	on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
-}
-EXPORT_SYMBOL(on_each_cpu_cond);
-
 static void do_nothing(void *unused)
 {
 }
diff --git a/kernel/up.c b/kernel/up.c
index c6f323d..bf20b4a 100644
--- a/kernel/up.c
+++ b/kernel/up.c
@@ -36,35 +36,6 @@ int smp_call_function_single_async(int cpu, call_single_data_t *csd)
 }
 EXPORT_SYMBOL(smp_call_function_single_async);
 
-void on_each_cpu(smp_call_func_t func, void *info, int wait)
-{
-	unsigned long flags;
-
-	local_irq_save(flags);
-	func(info);
-	local_irq_restore(flags);
-}
-EXPORT_SYMBOL(on_each_cpu);
-
-/*
- * Note we still need to test the mask even for UP
- * because we actually can get an empty mask from
- * code that on SMP might call us without the local
- * CPU in the mask.
- */
-void on_each_cpu_mask(const struct cpumask *mask,
-		      smp_call_func_t func, void *info, bool wait)
-{
-	unsigned long flags;
-
-	if (cpumask_test_cpu(0, mask)) {
-		local_irq_save(flags);
-		func(info);
-		local_irq_restore(flags);
-	}
-}
-EXPORT_SYMBOL(on_each_cpu_mask);
-
 /*
  * Preemption is disabled here to make sure the cond_func is called under the
  * same condtions in UP and SMP.
@@ -75,7 +46,7 @@ void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 	unsigned long flags;
 
 	preempt_disable();
-	if (cond_func(0, info)) {
+	if ((!cond_func || cond_func(0, info)) && cpumask_test_cpu(0, mask)) {
 		local_irq_save(flags);
 		func(info);
 		local_irq_restore(flags);
@@ -84,13 +55,6 @@ void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 }
 EXPORT_SYMBOL(on_each_cpu_cond_mask);
 
-void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
-		      void *info, bool wait)
-{
-	on_each_cpu_cond_mask(cond_func, func, info, wait, NULL);
-}
-EXPORT_SYMBOL(on_each_cpu_cond);
-
 int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
 {
 	int ret;

[tip: x86/mm] x86/mm/tlb: Remove unnecessary uses of the inline keyword

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     327db7a160b33865e086f7fff73e08f6d8d47005
Gitweb:        https://git.kernel.org/tip/327db7a160b33865e086f7fff73e08f6d8d47005
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:11 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 02 Mar 2021 08:01:38 +01:00

x86/mm/tlb: Remove unnecessary uses of the inline keyword

The compiler is smart enough without these hints.

Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-9-namit@vmware.com
---
 arch/x86/mm/tlb.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 17ec4bf..f4b162f 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -316,7 +316,7 @@ void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 	local_irq_restore(flags);
 }
 
-static inline unsigned long mm_mangle_tif_spec_ib(struct task_struct *next)
+static unsigned long mm_mangle_tif_spec_ib(struct task_struct *next)
 {
 	unsigned long next_tif = task_thread_info(next)->flags;
 	unsigned long ibpb = (next_tif >> TIF_SPEC_IB) & LAST_USER_MM_IBPB;
@@ -880,7 +880,7 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct flush_tlb_info, flush_tlb_info);
 static DEFINE_PER_CPU(unsigned int, flush_tlb_info_idx);
 #endif
 
-static inline struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
+static struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
 			unsigned long start, unsigned long end,
 			unsigned int stride_shift, bool freed_tables,
 			u64 new_tlb_gen)
@@ -907,7 +907,7 @@ static inline struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
 	return info;
 }
 
-static inline void put_flush_tlb_info(void)
+static void put_flush_tlb_info(void)
 {
 #ifdef CONFIG_DEBUG_VM
 	/* Complete reentrency prevention checks */

[tip: x86/mm] x86/mm/tlb: Privatize cpu_tlbstate

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     fe978069739b59804c911fc9e9645ce768ec5b9e
Gitweb:        https://git.kernel.org/tip/fe978069739b59804c911fc9e9645ce768ec5b9e
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:08 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 02 Mar 2021 08:01:37 +01:00

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 <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-6-namit@vmware.com
---
 arch/x86/include/asm/tlbflush.h | 39 +++++++++++++++++---------------
 arch/x86/kernel/alternative.c   |  2 +-
 arch/x86/mm/init.c              |  2 +-
 arch/x86/mm/tlb.c               | 17 ++++++++------
 4 files changed, 33 insertions(+), 27 deletions(-)

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 dd694fb..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)
 {

[tip: x86/mm] x86/mm/tlb: Flush remote and local TLBs concurrently

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     efa72447b0b95cd5e8b2bd7cf55ae23c716f8702
Gitweb:        https://git.kernel.org/tip/efa72447b0b95cd5e8b2bd7cf55ae23c716f8702
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:07 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 02 Mar 2021 08:01:37 +01:00

x86/mm/tlb: Flush remote and local TLBs concurrently

To improve TLB shootdown performance, flush the remote and local TLBs
concurrently. Introduce flush_tlb_multi() that does so. Introduce
paravirtual versions of flush_tlb_multi() for KVM, Xen and hyper-v (Xen
and hyper-v are only compile-tested).

While the updated smp infrastructure is capable of running a function on
a single local core, it is not optimized for this case. The multiple
function calls and the indirect branch introduce some overhead, and
might make local TLB flushes slower than they were before the recent
changes.

Before calling the SMP infrastructure, check if only a local TLB flush
is needed to restore the lost performance in this common case. This
requires to check mm_cpumask() one more time, but unless this mask is
updated very frequently, this should impact performance negatively.

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Michael Kelley <mikelley@microsoft.com> # Hyper-v parts
Reviewed-by: Juergen Gross <jgross@suse.com> # Xen and paravirt parts
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-5-namit@vmware.com
---
 arch/x86/hyperv/mmu.c                 | 10 +++---
 arch/x86/include/asm/paravirt.h       |  6 +--
 arch/x86/include/asm/paravirt_types.h |  4 +-
 arch/x86/include/asm/tlbflush.h       |  4 +-
 arch/x86/include/asm/trace/hyperv.h   |  2 +-
 arch/x86/kernel/kvm.c                 | 11 ++++--
 arch/x86/kernel/paravirt.c            |  2 +-
 arch/x86/mm/tlb.c                     | 46 ++++++++++++++++----------
 arch/x86/xen/mmu_pv.c                 | 11 ++----
 include/trace/events/xen.h            |  2 +-
 10 files changed, 57 insertions(+), 41 deletions(-)

diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c
index 2c87350..681dba8 100644
--- a/arch/x86/hyperv/mmu.c
+++ b/arch/x86/hyperv/mmu.c
@@ -52,8 +52,8 @@ static inline int fill_gva_list(u64 gva_list[], int offset,
 	return gva_n - offset;
 }
 
-static void hyperv_flush_tlb_others(const struct cpumask *cpus,
-				    const struct flush_tlb_info *info)
+static void hyperv_flush_tlb_multi(const struct cpumask *cpus,
+				   const struct flush_tlb_info *info)
 {
 	int cpu, vcpu, gva_n, max_gvas;
 	struct hv_tlb_flush **flush_pcpu;
@@ -61,7 +61,7 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
 	u64 status = U64_MAX;
 	unsigned long flags;
 
-	trace_hyperv_mmu_flush_tlb_others(cpus, info);
+	trace_hyperv_mmu_flush_tlb_multi(cpus, info);
 
 	if (!hv_hypercall_pg)
 		goto do_native;
@@ -164,7 +164,7 @@ check_status:
 	if (!(status & HV_HYPERCALL_RESULT_MASK))
 		return;
 do_native:
-	native_flush_tlb_others(cpus, info);
+	native_flush_tlb_multi(cpus, info);
 }
 
 static u64 hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
@@ -239,6 +239,6 @@ void hyperv_setup_mmu_ops(void)
 		return;
 
 	pr_info("Using hypercall for remote TLB flush\n");
-	pv_ops.mmu.flush_tlb_others = hyperv_flush_tlb_others;
+	pv_ops.mmu.flush_tlb_multi = hyperv_flush_tlb_multi;
 	pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 }
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 4abf110..45b55e3 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -50,7 +50,7 @@ static inline void slow_down_io(void)
 void native_flush_tlb_local(void);
 void native_flush_tlb_global(void);
 void native_flush_tlb_one_user(unsigned long addr);
-void native_flush_tlb_others(const struct cpumask *cpumask,
+void native_flush_tlb_multi(const struct cpumask *cpumask,
 			     const struct flush_tlb_info *info);
 
 static inline void __flush_tlb_local(void)
@@ -68,10 +68,10 @@ static inline void __flush_tlb_one_user(unsigned long addr)
 	PVOP_VCALL1(mmu.flush_tlb_one_user, addr);
 }
 
-static inline void __flush_tlb_others(const struct cpumask *cpumask,
+static inline void __flush_tlb_multi(const struct cpumask *cpumask,
 				      const struct flush_tlb_info *info)
 {
-	PVOP_VCALL2(mmu.flush_tlb_others, cpumask, info);
+	PVOP_VCALL2(mmu.flush_tlb_multi, cpumask, info);
 }
 
 static inline void paravirt_tlb_remove_table(struct mmu_gather *tlb, void *table)
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index de87087..b7b35d5 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -188,8 +188,8 @@ struct pv_mmu_ops {
 	void (*flush_tlb_user)(void);
 	void (*flush_tlb_kernel)(void);
 	void (*flush_tlb_one_user)(unsigned long addr);
-	void (*flush_tlb_others)(const struct cpumask *cpus,
-				 const struct flush_tlb_info *info);
+	void (*flush_tlb_multi)(const struct cpumask *cpus,
+				const struct flush_tlb_info *info);
 
 	void (*tlb_remove_table)(struct mmu_gather *tlb, void *table);
 
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index a7a598a..3c6681d 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -175,7 +175,7 @@ extern void initialize_tlbstate_and_flush(void);
  *  - flush_tlb_page(vma, vmaddr) flushes one page
  *  - flush_tlb_range(vma, start, end) flushes a range of pages
  *  - flush_tlb_kernel_range(start, end) flushes a range of kernel pages
- *  - flush_tlb_others(cpumask, info) flushes TLBs on other cpus
+ *  - flush_tlb_multi(cpumask, info) flushes TLBs on multiple cpus
  *
  * ..but the i386 has somewhat limited tlb flushing capabilities,
  * and page-granular flushes are available only on i486 and up.
@@ -209,7 +209,7 @@ struct flush_tlb_info {
 void flush_tlb_local(void);
 void flush_tlb_one_user(unsigned long addr);
 void flush_tlb_one_kernel(unsigned long addr);
-void flush_tlb_others(const struct cpumask *cpumask,
+void flush_tlb_multi(const struct cpumask *cpumask,
 		      const struct flush_tlb_info *info);
 
 #ifdef CONFIG_PARAVIRT
diff --git a/arch/x86/include/asm/trace/hyperv.h b/arch/x86/include/asm/trace/hyperv.h
index 4d705cb..a8e5a7a 100644
--- a/arch/x86/include/asm/trace/hyperv.h
+++ b/arch/x86/include/asm/trace/hyperv.h
@@ -8,7 +8,7 @@
 
 #if IS_ENABLED(CONFIG_HYPERV)
 
-TRACE_EVENT(hyperv_mmu_flush_tlb_others,
+TRACE_EVENT(hyperv_mmu_flush_tlb_multi,
 	    TP_PROTO(const struct cpumask *cpus,
 		     const struct flush_tlb_info *info),
 	    TP_ARGS(cpus, info),
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5e78e01..38ea9de 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -613,7 +613,7 @@ static int kvm_cpu_down_prepare(unsigned int cpu)
 }
 #endif
 
-static void kvm_flush_tlb_others(const struct cpumask *cpumask,
+static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
 			const struct flush_tlb_info *info)
 {
 	u8 state;
@@ -627,6 +627,11 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask,
 	 * queue flush_on_enter for pre-empted vCPUs
 	 */
 	for_each_cpu(cpu, flushmask) {
+		/*
+		 * The local vCPU is never preempted, so we do not explicitly
+		 * skip check for local vCPU - it will never be cleared from
+		 * flushmask.
+		 */
 		src = &per_cpu(steal_time, cpu);
 		state = READ_ONCE(src->preempted);
 		if ((state & KVM_VCPU_PREEMPTED)) {
@@ -636,7 +641,7 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask,
 		}
 	}
 
-	native_flush_tlb_others(flushmask, info);
+	native_flush_tlb_multi(flushmask, info);
 }
 
 static void __init kvm_guest_init(void)
@@ -654,7 +659,7 @@ static void __init kvm_guest_init(void)
 	}
 
 	if (pv_tlb_flush_supported()) {
-		pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
+		pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
 		pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 		pr_info("KVM setup pv remote TLB flush\n");
 	}
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index c60222a..197a126 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -330,7 +330,7 @@ struct paravirt_patch_template pv_ops = {
 	.mmu.flush_tlb_user	= native_flush_tlb_local,
 	.mmu.flush_tlb_kernel	= native_flush_tlb_global,
 	.mmu.flush_tlb_one_user	= native_flush_tlb_one_user,
-	.mmu.flush_tlb_others	= native_flush_tlb_others,
+	.mmu.flush_tlb_multi	= native_flush_tlb_multi,
 	.mmu.tlb_remove_table	=
 			(void (*)(struct mmu_gather *, void *))tlb_remove_page,
 
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 07b6701..8db87cd 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -24,7 +24,7 @@
 # define __flush_tlb_local		native_flush_tlb_local
 # define __flush_tlb_global		native_flush_tlb_global
 # define __flush_tlb_one_user(addr)	native_flush_tlb_one_user(addr)
-# define __flush_tlb_others(msk, info)	native_flush_tlb_others(msk, info)
+# define __flush_tlb_multi(msk, info)	native_flush_tlb_multi(msk, info)
 #endif
 
 /*
@@ -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
-		 * from cpu_tlbstate.is_lazy whether or not to send an IPI.
+		 * cpu_tlbstate.is_lazy whether or not to send an IPI.
 		 */
 		if (WARN_ON_ONCE(real_prev != &init_mm &&
 				 !cpumask_test_cpu(cpu, mm_cpumask(next))))
@@ -697,7 +697,7 @@ static void flush_tlb_func(void *info)
 		 * garbage into our TLB.  Since switching to init_mm is barely
 		 * slower than a minimal flush, just switch to init_mm.
 		 *
-		 * This should be rare, with native_flush_tlb_others skipping
+		 * This should be rare, with native_flush_tlb_multi() skipping
 		 * IPIs to lazy TLB mode CPUs.
 		 */
 		switch_mm_irqs_off(NULL, &init_mm, NULL);
@@ -795,9 +795,14 @@ static bool tlb_is_not_lazy(int cpu)
 
 static DEFINE_PER_CPU(cpumask_t, flush_tlb_mask);
 
-STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
+STATIC_NOPV void native_flush_tlb_multi(const struct cpumask *cpumask,
 					 const struct flush_tlb_info *info)
 {
+	/*
+	 * Do accounting and tracing. Note that there are (and have always been)
+	 * cases in which a remote TLB flush will be traced, but eventually
+	 * would not happen.
+	 */
 	count_vm_tlb_event(NR_TLB_REMOTE_FLUSH);
 	if (info->end == TLB_FLUSH_ALL)
 		trace_tlb_flush(TLB_REMOTE_SEND_IPI, TLB_FLUSH_ALL);
@@ -816,8 +821,7 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 	 * doing a speculative memory access.
 	 */
 	if (info->freed_tables) {
-		smp_call_function_many(cpumask, flush_tlb_func,
-			       (void *)info, 1);
+		on_each_cpu_mask(cpumask, flush_tlb_func, (void *)info, true);
 	} else {
 		/*
 		 * Although we could have used on_each_cpu_cond_mask(),
@@ -844,14 +848,14 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 			if (tlb_is_not_lazy(cpu))
 				__cpumask_set_cpu(cpu, cond_cpumask);
 		}
-		smp_call_function_many(cond_cpumask, flush_tlb_func, (void *)info, 1);
+		on_each_cpu_mask(cond_cpumask, flush_tlb_func, (void *)info, true);
 	}
 }
 
-void flush_tlb_others(const struct cpumask *cpumask,
+void flush_tlb_multi(const struct cpumask *cpumask,
 		      const struct flush_tlb_info *info)
 {
-	__flush_tlb_others(cpumask, info);
+	__flush_tlb_multi(cpumask, info);
 }
 
 /*
@@ -931,16 +935,20 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 	info = get_flush_tlb_info(mm, start, end, stride_shift, freed_tables,
 				  new_tlb_gen);
 
-	if (mm == this_cpu_read(cpu_tlbstate.loaded_mm)) {
+	/*
+	 * flush_tlb_multi() is not optimized for the common case in which only
+	 * a local TLB flush is needed. Optimize this use-case by calling
+	 * flush_tlb_func_local() directly in this case.
+	 */
+	if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids) {
+		flush_tlb_multi(mm_cpumask(mm), info);
+	} else if (mm == this_cpu_read(cpu_tlbstate.loaded_mm)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
 		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
-	if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids)
-		flush_tlb_others(mm_cpumask(mm), info);
-
 	put_flush_tlb_info();
 	put_cpu();
 }
@@ -1152,16 +1160,20 @@ void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
 	int cpu = get_cpu();
 
 	info = get_flush_tlb_info(NULL, 0, TLB_FLUSH_ALL, 0, false, 0);
-	if (cpumask_test_cpu(cpu, &batch->cpumask)) {
+	/*
+	 * flush_tlb_multi() is not optimized for the common case in which only
+	 * a local TLB flush is needed. Optimize this use-case by calling
+	 * flush_tlb_func_local() directly in this case.
+	 */
+	if (cpumask_any_but(&batch->cpumask, cpu) < nr_cpu_ids) {
+		flush_tlb_multi(&batch->cpumask, info);
+	} else if (cpumask_test_cpu(cpu, &batch->cpumask)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
 		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
-	if (cpumask_any_but(&batch->cpumask, cpu) < nr_cpu_ids)
-		flush_tlb_others(&batch->cpumask, info);
-
 	cpumask_clear(&batch->cpumask);
 
 	put_flush_tlb_info();
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index cf2ade8..09b95c0 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -1247,8 +1247,8 @@ static void xen_flush_tlb_one_user(unsigned long addr)
 	preempt_enable();
 }
 
-static void xen_flush_tlb_others(const struct cpumask *cpus,
-				 const struct flush_tlb_info *info)
+static void xen_flush_tlb_multi(const struct cpumask *cpus,
+				const struct flush_tlb_info *info)
 {
 	struct {
 		struct mmuext_op op;
@@ -1258,7 +1258,7 @@ static void xen_flush_tlb_others(const struct cpumask *cpus,
 	const size_t mc_entry_size = sizeof(args->op) +
 		sizeof(args->mask[0]) * BITS_TO_LONGS(num_possible_cpus());
 
-	trace_xen_mmu_flush_tlb_others(cpus, info->mm, info->start, info->end);
+	trace_xen_mmu_flush_tlb_multi(cpus, info->mm, info->start, info->end);
 
 	if (cpumask_empty(cpus))
 		return;		/* nothing to do */
@@ -1267,9 +1267,8 @@ static void xen_flush_tlb_others(const struct cpumask *cpus,
 	args = mcs.args;
 	args->op.arg2.vcpumask = to_cpumask(args->mask);
 
-	/* Remove us, and any offline CPUS. */
+	/* Remove any offline CPUs */
 	cpumask_and(to_cpumask(args->mask), cpus, cpu_online_mask);
-	cpumask_clear_cpu(smp_processor_id(), to_cpumask(args->mask));
 
 	args->op.cmd = MMUEXT_TLB_FLUSH_MULTI;
 	if (info->end != TLB_FLUSH_ALL &&
@@ -2086,7 +2085,7 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = {
 	.flush_tlb_user = xen_flush_tlb,
 	.flush_tlb_kernel = xen_flush_tlb,
 	.flush_tlb_one_user = xen_flush_tlb_one_user,
-	.flush_tlb_others = xen_flush_tlb_others,
+	.flush_tlb_multi = xen_flush_tlb_multi,
 	.tlb_remove_table = tlb_remove_table,
 
 	.pgd_alloc = xen_pgd_alloc,
diff --git a/include/trace/events/xen.h b/include/trace/events/xen.h
index 3b61b58..44a3f56 100644
--- a/include/trace/events/xen.h
+++ b/include/trace/events/xen.h
@@ -346,7 +346,7 @@ TRACE_EVENT(xen_mmu_flush_tlb_one_user,
 	    TP_printk("addr %lx", __entry->addr)
 	);
 
-TRACE_EVENT(xen_mmu_flush_tlb_others,
+TRACE_EVENT(xen_mmu_flush_tlb_multi,
 	    TP_PROTO(const struct cpumask *cpus, struct mm_struct *mm,
 		     unsigned long addr, unsigned long end),
 	    TP_ARGS(cpus, mm, addr, end),

[tip: x86/mm] cpumask: Mark functions as pure

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     1028a5918cbaae6b9d7f0a04b6a200b9e67aec14
Gitweb:        https://git.kernel.org/tip/1028a5918cbaae6b9d7f0a04b6a200b9e67aec14
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:10 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 02 Mar 2021 08:01:38 +01:00

cpumask: Mark functions as pure

cpumask_next_and() and cpumask_any_but() are pure, and marking them as
such seems to generate different and presumably better code for
native_flush_tlb_multi().

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-8-namit@vmware.com
---
 include/linux/cpumask.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 383684e..c53364c 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -235,7 +235,7 @@ static inline unsigned int cpumask_last(const struct cpumask *srcp)
 	return find_last_bit(cpumask_bits(srcp), nr_cpumask_bits);
 }
 
-unsigned int cpumask_next(int n, const struct cpumask *srcp);
+unsigned int __pure cpumask_next(int n, const struct cpumask *srcp);
 
 /**
  * cpumask_next_zero - get the next unset cpu in a cpumask
@@ -252,8 +252,8 @@ static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
 	return find_next_zero_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
 }
 
-int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
-int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
+int __pure cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
+int __pure cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
 unsigned int cpumask_local_spread(unsigned int i, int node);
 int cpumask_any_and_distribute(const struct cpumask *src1p,
 			       const struct cpumask *src2p);

[tip: x86/mm] x86/mm/tlb: Do not make is_lazy dirty for no reason

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     db73f8099a502be8ed46f6332c91754c74ac76c2
Gitweb:        https://git.kernel.org/tip/db73f8099a502be8ed46f6332c91754c74ac76c2
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:09 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 02 Mar 2021 08:01:38 +01:00

x86/mm/tlb: Do not make is_lazy dirty for no reason

Blindly writing to is_lazy for no reason, when the written value is
identical to the old value, makes the cacheline dirty for no reason.
Avoid making such writes to prevent cache coherency traffic for no
reason.

Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-7-namit@vmware.com
---
 arch/x86/mm/tlb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 345a0af..17ec4bf 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -469,7 +469,8 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 		__flush_tlb_all();
 	}
 #endif
-	this_cpu_write(cpu_tlbstate_shared.is_lazy, false);
+	if (was_lazy)
+		this_cpu_write(cpu_tlbstate_shared.is_lazy, false);
 
 	/*
 	 * The membarrier system call requires a full memory barrier and

[tip: x86/mm] x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy()

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     bc51e8e6f9c387d8dda1d8dea2b8856d0ade4101
Gitweb:        https://git.kernel.org/tip/bc51e8e6f9c387d8dda1d8dea2b8856d0ade4101
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:06 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 02 Mar 2021 08:01:37 +01:00

x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy()

Open-code on_each_cpu_cond_mask() in native_flush_tlb_others() to
optimize the code. Open-coding eliminates the need for the indirect branch
that is used to call is_lazy(), and in CPUs that are vulnerable to
Spectre v2, it eliminates the retpoline. In addition, it allows to use a
preallocated cpumask to compute the CPUs that should be.

This would later allow us not to adapt on_each_cpu_cond_mask() to
support local and remote functions.

Note that calling tlb_is_not_lazy() for every CPU that needs to be
flushed, as done in native_flush_tlb_multi() might look ugly, but it is
equivalent to what is currently done in on_each_cpu_cond_mask().
Actually, native_flush_tlb_multi() does it more efficiently since it
avoids using an indirect branch for the matter.

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-4-namit@vmware.com
---
 arch/x86/mm/tlb.c | 37 ++++++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index bf12371..07b6701 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -788,11 +788,13 @@ done:
 			nr_invalidate);
 }
 
-static bool tlb_is_not_lazy(int cpu, void *data)
+static bool tlb_is_not_lazy(int cpu)
 {
 	return !per_cpu(cpu_tlbstate.is_lazy, cpu);
 }
 
+static DEFINE_PER_CPU(cpumask_t, flush_tlb_mask);
+
 STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 					 const struct flush_tlb_info *info)
 {
@@ -813,12 +815,37 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 	 * up on the new contents of what used to be page tables, while
 	 * doing a speculative memory access.
 	 */
-	if (info->freed_tables)
+	if (info->freed_tables) {
 		smp_call_function_many(cpumask, flush_tlb_func,
 			       (void *)info, 1);
-	else
-		on_each_cpu_cond_mask(tlb_is_not_lazy, flush_tlb_func,
-				(void *)info, 1, cpumask);
+	} else {
+		/*
+		 * Although we could have used on_each_cpu_cond_mask(),
+		 * open-coding it has performance advantages, as it eliminates
+		 * the need for indirect calls or retpolines. In addition, it
+		 * allows to use a designated cpumask for evaluating the
+		 * condition, instead of allocating one.
+		 *
+		 * This code works under the assumption that there are no nested
+		 * TLB flushes, an assumption that is already made in
+		 * flush_tlb_mm_range().
+		 *
+		 * cond_cpumask is logically a stack-local variable, but it is
+		 * more efficient to have it off the stack and not to allocate
+		 * it on demand. Preemption is disabled and this code is
+		 * non-reentrant.
+		 */
+		struct cpumask *cond_cpumask = this_cpu_ptr(&flush_tlb_mask);
+		int cpu;
+
+		cpumask_clear(cond_cpumask);
+
+		for_each_cpu(cpu, cpumask) {
+			if (tlb_is_not_lazy(cpu))
+				__cpumask_set_cpu(cpu, cond_cpumask);
+		}
+		smp_call_function_many(cond_cpumask, flush_tlb_func, (void *)info, 1);
+	}
 }
 
 void flush_tlb_others(const struct cpumask *cpumask,

[tip: x86/mm] smp: Run functions concurrently in smp_call_function_many_cond()

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     b54d50640ca698383fc5b711487f303c17f4b47f
Gitweb:        https://git.kernel.org/tip/b54d50640ca698383fc5b711487f303c17f4b47f
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:04 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 02 Mar 2021 08:01:37 +01:00

smp: Run functions concurrently in smp_call_function_many_cond()

Currently, on_each_cpu() and similar functions do not exploit the
potential of concurrency: the function is first executed remotely and
only then it is executed locally. Functions such as TLB flush can take
considerable time, so this provides an opportunity for performance
optimization.

To do so, modify smp_call_function_many_cond(), to allows the callers to
provide a function that should be executed (remotely/locally), and run
them concurrently. Keep other smp_call_function_many() semantic as it is
today for backward compatibility: the called function is not executed in
this case locally.

smp_call_function_many_cond() does not use the optimized version for a
single remote target that smp_call_function_single() implements. For
synchronous function call, smp_call_function_single() keeps a
call_single_data (which is used for synchronization) on the stack.
Interestingly, it seems that not using this optimization provides
greater performance improvements (greater speedup with a single remote
target than with multiple ones). Presumably, holding data structures
that are intended for synchronization on the stack can introduce
overheads due to TLB misses and false-sharing when the stack is used for
other purposes.

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-2-namit@vmware.com
---
 kernel/smp.c | 156 ++++++++++++++++++++++++++++----------------------
 1 file changed, 88 insertions(+), 68 deletions(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index aeb0adf..c8a5a1f 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -608,12 +608,28 @@ call:
 }
 EXPORT_SYMBOL_GPL(smp_call_function_any);
 
+/*
+ * Flags to be used as scf_flags argument of smp_call_function_many_cond().
+ *
+ * %SCF_WAIT:		Wait until function execution is completed
+ * %SCF_RUN_LOCAL:	Run also locally if local cpu is set in cpumask
+ */
+#define SCF_WAIT	(1U << 0)
+#define SCF_RUN_LOCAL	(1U << 1)
+
 static void smp_call_function_many_cond(const struct cpumask *mask,
 					smp_call_func_t func, void *info,
-					bool wait, smp_cond_func_t cond_func)
+					unsigned int scf_flags,
+					smp_cond_func_t cond_func)
 {
+	int cpu, last_cpu, this_cpu = smp_processor_id();
 	struct call_function_data *cfd;
-	int cpu, next_cpu, this_cpu = smp_processor_id();
+	bool wait = scf_flags & SCF_WAIT;
+	bool run_remote = false;
+	bool run_local = false;
+	int nr_cpus = 0;
+
+	lockdep_assert_preemption_disabled();
 
 	/*
 	 * Can deadlock when called with interrupts disabled.
@@ -621,8 +637,9 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 	 * send smp call function interrupt to this cpu and as such deadlocks
 	 * can't happen.
 	 */
-	WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
-		     && !oops_in_progress && !early_boot_irqs_disabled);
+	if (cpu_online(this_cpu) && !oops_in_progress &&
+	    !early_boot_irqs_disabled)
+		lockdep_assert_irqs_enabled();
 
 	/*
 	 * When @wait we can deadlock when we interrupt between llist_add() and
@@ -632,60 +649,65 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 	 */
 	WARN_ON_ONCE(!in_task());
 
-	/* Try to fastpath.  So, what's a CPU they want? Ignoring this one. */
+	/* Check if we need local execution. */
+	if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(this_cpu, mask))
+		run_local = true;
+
+	/* Check if we need remote execution, i.e., any CPU excluding this one. */
 	cpu = cpumask_first_and(mask, cpu_online_mask);
 	if (cpu == this_cpu)
 		cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
+	if (cpu < nr_cpu_ids)
+		run_remote = true;
 
-	/* No online cpus?  We're done. */
-	if (cpu >= nr_cpu_ids)
-		return;
-
-	/* Do we have another CPU which isn't us? */
-	next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
-	if (next_cpu == this_cpu)
-		next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
-
-	/* Fastpath: do that cpu by itself. */
-	if (next_cpu >= nr_cpu_ids) {
-		if (!cond_func || cond_func(cpu, info))
-			smp_call_function_single(cpu, func, info, wait);
-		return;
-	}
-
-	cfd = this_cpu_ptr(&cfd_data);
+	if (run_remote) {
+		cfd = this_cpu_ptr(&cfd_data);
+		cpumask_and(cfd->cpumask, mask, cpu_online_mask);
+		__cpumask_clear_cpu(this_cpu, cfd->cpumask);
 
-	cpumask_and(cfd->cpumask, mask, cpu_online_mask);
-	__cpumask_clear_cpu(this_cpu, cfd->cpumask);
-
-	/* Some callers race with other cpus changing the passed mask */
-	if (unlikely(!cpumask_weight(cfd->cpumask)))
-		return;
+		cpumask_clear(cfd->cpumask_ipi);
+		for_each_cpu(cpu, cfd->cpumask) {
+			call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
 
-	cpumask_clear(cfd->cpumask_ipi);
-	for_each_cpu(cpu, cfd->cpumask) {
-		call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
+			if (cond_func && !cond_func(cpu, info))
+				continue;
 
-		if (cond_func && !cond_func(cpu, info))
-			continue;
-
-		csd_lock(csd);
-		if (wait)
-			csd->node.u_flags |= CSD_TYPE_SYNC;
-		csd->func = func;
-		csd->info = info;
+			csd_lock(csd);
+			if (wait)
+				csd->node.u_flags |= CSD_TYPE_SYNC;
+			csd->func = func;
+			csd->info = info;
 #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
-		csd->node.src = smp_processor_id();
-		csd->node.dst = cpu;
+			csd->node.src = smp_processor_id();
+			csd->node.dst = cpu;
 #endif
-		if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu)))
-			__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
+			if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) {
+				__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
+				nr_cpus++;
+				last_cpu = cpu;
+			}
+		}
+
+		/*
+		 * Choose the most efficient way to send an IPI. Note that the
+		 * number of CPUs might be zero due to concurrent changes to the
+		 * provided mask.
+		 */
+		if (nr_cpus == 1)
+			arch_send_call_function_single_ipi(last_cpu);
+		else if (likely(nr_cpus > 1))
+			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
 	}
 
-	/* Send a message to all CPUs in the map */
-	arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
+	if (run_local && (!cond_func || cond_func(this_cpu, info))) {
+		unsigned long flags;
 
-	if (wait) {
+		local_irq_save(flags);
+		func(info);
+		local_irq_restore(flags);
+	}
+
+	if (run_remote && wait) {
 		for_each_cpu(cpu, cfd->cpumask) {
 			call_single_data_t *csd;
 
@@ -696,12 +718,14 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 }
 
 /**
- * smp_call_function_many(): Run a function on a set of other CPUs.
+ * smp_call_function_many(): Run a function on a set of CPUs.
  * @mask: The set of cpus to run on (only runs on online subset).
  * @func: The function to run. This must be fast and non-blocking.
  * @info: An arbitrary pointer to pass to the function.
- * @wait: If true, wait (atomically) until function has completed
- *        on other CPUs.
+ * @flags: Bitmask that controls the operation. If %SCF_WAIT is set, wait
+ *        (atomically) until function has completed on other CPUs. If
+ *        %SCF_RUN_LOCAL is set, the function will also be run locally
+ *        if the local CPU is set in the @cpumask.
  *
  * If @wait is true, then returns once @func has returned.
  *
@@ -712,7 +736,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 void smp_call_function_many(const struct cpumask *mask,
 			    smp_call_func_t func, void *info, bool wait)
 {
-	smp_call_function_many_cond(mask, func, info, wait, NULL);
+	smp_call_function_many_cond(mask, func, info, wait * SCF_WAIT, NULL);
 }
 EXPORT_SYMBOL(smp_call_function_many);
 
@@ -860,16 +884,15 @@ EXPORT_SYMBOL(on_each_cpu);
 void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
 			void *info, bool wait)
 {
-	int cpu = get_cpu();
+	unsigned int scf_flags;
 
-	smp_call_function_many(mask, func, info, wait);
-	if (cpumask_test_cpu(cpu, mask)) {
-		unsigned long flags;
-		local_irq_save(flags);
-		func(info);
-		local_irq_restore(flags);
-	}
-	put_cpu();
+	scf_flags = SCF_RUN_LOCAL;
+	if (wait)
+		scf_flags |= SCF_WAIT;
+
+	preempt_disable();
+	smp_call_function_many_cond(mask, func, info, scf_flags, NULL);
+	preempt_enable();
 }
 EXPORT_SYMBOL(on_each_cpu_mask);
 
@@ -898,17 +921,14 @@ EXPORT_SYMBOL(on_each_cpu_mask);
 void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 			   void *info, bool wait, const struct cpumask *mask)
 {
-	int cpu = get_cpu();
+	unsigned int scf_flags = SCF_RUN_LOCAL;
 
-	smp_call_function_many_cond(mask, func, info, wait, cond_func);
-	if (cpumask_test_cpu(cpu, mask) && cond_func(cpu, info)) {
-		unsigned long flags;
+	if (wait)
+		scf_flags |= SCF_WAIT;
 
-		local_irq_save(flags);
-		func(info);
-		local_irq_restore(flags);
-	}
-	put_cpu();
+	preempt_disable();
+	smp_call_function_many_cond(mask, func, info, scf_flags, cond_func);
+	preempt_enable();
 }
 EXPORT_SYMBOL(on_each_cpu_cond_mask);
 

[tip: x86/mm] x86/mm/tlb: Unify flush_tlb_func_local() and flush_tlb_func_remote()

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     f4f14f7c20440a442b4eaeb7b6f25cd0fc437e36
Gitweb:        https://git.kernel.org/tip/f4f14f7c20440a442b4eaeb7b6f25cd0fc437e36
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:05 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 02 Mar 2021 08:01:37 +01:00

x86/mm/tlb: Unify flush_tlb_func_local() and flush_tlb_func_remote()

The unification of these two functions allows to use them in the updated
SMP infrastrucutre.

To do so, remove the reason argument from flush_tlb_func_local(), add
a member to struct tlb_flush_info that says which CPU initiated the
flush and act accordingly. Optimize the size of flush_tlb_info while we
are at it.

Unfortunately, this prevents us from using a constant tlb_flush_info for
arch_tlbbatch_flush(), but in a later stage we may be able to inline
tlb_flush_info into the IPI data, so it should not have an impact
eventually.

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-3-namit@vmware.com
---
 arch/x86/include/asm/tlbflush.h |  5 +-
 arch/x86/mm/tlb.c               | 81 ++++++++++++++------------------
 2 files changed, 39 insertions(+), 47 deletions(-)

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 8c87a2e..a7a598a 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -201,8 +201,9 @@ struct flush_tlb_info {
 	unsigned long		start;
 	unsigned long		end;
 	u64			new_tlb_gen;
-	unsigned int		stride_shift;
-	bool			freed_tables;
+	unsigned int		initiating_cpu;
+	u8			stride_shift;
+	u8			freed_tables;
 };
 
 void flush_tlb_local(void);
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 569ac1d..bf12371 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -439,7 +439,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 	 * NB: leave_mm() calls us with prev == NULL and tsk == NULL.
 	 */
 
-	/* We don't want flush_tlb_func_* to run concurrently with us. */
+	/* We don't want flush_tlb_func() to run concurrently with us. */
 	if (IS_ENABLED(CONFIG_PROVE_LOCKING))
 		WARN_ON_ONCE(!irqs_disabled());
 
@@ -647,14 +647,13 @@ void initialize_tlbstate_and_flush(void)
 }
 
 /*
- * flush_tlb_func_common()'s memory ordering requirement is that any
+ * flush_tlb_func()'s memory ordering requirement is that any
  * TLB fills that happen after we flush the TLB are ordered after we
  * read active_mm's tlb_gen.  We don't need any explicit barriers
  * because all x86 flush operations are serializing and the
  * atomic64_read operation won't be reordered by the compiler.
  */
-static void flush_tlb_func_common(const struct flush_tlb_info *f,
-				  bool local, enum tlb_flush_reason reason)
+static void flush_tlb_func(void *info)
 {
 	/*
 	 * We have three different tlb_gen values in here.  They are:
@@ -665,14 +664,26 @@ static void flush_tlb_func_common(const struct flush_tlb_info *f,
 	 * - f->new_tlb_gen: the generation that the requester of the flush
 	 *                   wants us to catch up to.
 	 */
+	const struct flush_tlb_info *f = info;
 	struct mm_struct *loaded_mm = this_cpu_read(cpu_tlbstate.loaded_mm);
 	u32 loaded_mm_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid);
 	u64 mm_tlb_gen = atomic64_read(&loaded_mm->context.tlb_gen);
 	u64 local_tlb_gen = this_cpu_read(cpu_tlbstate.ctxs[loaded_mm_asid].tlb_gen);
+	bool local = smp_processor_id() == f->initiating_cpu;
+	unsigned long nr_invalidate = 0;
 
 	/* This code cannot presently handle being reentered. */
 	VM_WARN_ON(!irqs_disabled());
 
+	if (!local) {
+		inc_irq_stat(irq_tlb_count);
+		count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
+
+		/* Can only happen on remote CPUs */
+		if (f->mm && f->mm != loaded_mm)
+			return;
+	}
+
 	if (unlikely(loaded_mm == &init_mm))
 		return;
 
@@ -700,8 +711,7 @@ static void flush_tlb_func_common(const struct flush_tlb_info *f,
 		 * be handled can catch us all the way up, leaving no work for
 		 * the second flush.
 		 */
-		trace_tlb_flush(reason, 0);
-		return;
+		goto done;
 	}
 
 	WARN_ON_ONCE(local_tlb_gen > mm_tlb_gen);
@@ -748,46 +758,34 @@ static void flush_tlb_func_common(const struct flush_tlb_info *f,
 	    f->new_tlb_gen == local_tlb_gen + 1 &&
 	    f->new_tlb_gen == mm_tlb_gen) {
 		/* Partial flush */
-		unsigned long nr_invalidate = (f->end - f->start) >> f->stride_shift;
 		unsigned long addr = f->start;
 
+		nr_invalidate = (f->end - f->start) >> f->stride_shift;
+
 		while (addr < f->end) {
 			flush_tlb_one_user(addr);
 			addr += 1UL << f->stride_shift;
 		}
 		if (local)
 			count_vm_tlb_events(NR_TLB_LOCAL_FLUSH_ONE, nr_invalidate);
-		trace_tlb_flush(reason, nr_invalidate);
 	} else {
 		/* Full flush. */
+		nr_invalidate = TLB_FLUSH_ALL;
+
 		flush_tlb_local();
 		if (local)
 			count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
-		trace_tlb_flush(reason, TLB_FLUSH_ALL);
 	}
 
 	/* Both paths above update our state to mm_tlb_gen. */
 	this_cpu_write(cpu_tlbstate.ctxs[loaded_mm_asid].tlb_gen, mm_tlb_gen);
-}
-
-static void flush_tlb_func_local(const void *info, enum tlb_flush_reason reason)
-{
-	const struct flush_tlb_info *f = info;
-
-	flush_tlb_func_common(f, true, reason);
-}
 
-static void flush_tlb_func_remote(void *info)
-{
-	const struct flush_tlb_info *f = info;
-
-	inc_irq_stat(irq_tlb_count);
-
-	if (f->mm && f->mm != this_cpu_read(cpu_tlbstate.loaded_mm))
-		return;
-
-	count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
-	flush_tlb_func_common(f, false, TLB_REMOTE_SHOOTDOWN);
+	/* Tracing is done in a unified manner to reduce the code size */
+done:
+	trace_tlb_flush(!local ? TLB_REMOTE_SHOOTDOWN :
+				(f->mm == NULL) ? TLB_LOCAL_SHOOTDOWN :
+						  TLB_LOCAL_MM_SHOOTDOWN,
+			nr_invalidate);
 }
 
 static bool tlb_is_not_lazy(int cpu, void *data)
@@ -816,10 +814,10 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 	 * doing a speculative memory access.
 	 */
 	if (info->freed_tables)
-		smp_call_function_many(cpumask, flush_tlb_func_remote,
+		smp_call_function_many(cpumask, flush_tlb_func,
 			       (void *)info, 1);
 	else
-		on_each_cpu_cond_mask(tlb_is_not_lazy, flush_tlb_func_remote,
+		on_each_cpu_cond_mask(tlb_is_not_lazy, flush_tlb_func,
 				(void *)info, 1, cpumask);
 }
 
@@ -869,6 +867,7 @@ static inline struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
 	info->stride_shift	= stride_shift;
 	info->freed_tables	= freed_tables;
 	info->new_tlb_gen	= new_tlb_gen;
+	info->initiating_cpu	= smp_processor_id();
 
 	return info;
 }
@@ -908,7 +907,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 	if (mm == this_cpu_read(cpu_tlbstate.loaded_mm)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
-		flush_tlb_func_local(info, TLB_LOCAL_MM_SHOOTDOWN);
+		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
@@ -1119,34 +1118,26 @@ void __flush_tlb_all(void)
 }
 EXPORT_SYMBOL_GPL(__flush_tlb_all);
 
-/*
- * arch_tlbbatch_flush() performs a full TLB flush regardless of the active mm.
- * This means that the 'struct flush_tlb_info' that describes which mappings to
- * flush is actually fixed. We therefore set a single fixed struct and use it in
- * arch_tlbbatch_flush().
- */
-static const struct flush_tlb_info full_flush_tlb_info = {
-	.mm = NULL,
-	.start = 0,
-	.end = TLB_FLUSH_ALL,
-};
-
 void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
 {
+	struct flush_tlb_info *info;
+
 	int cpu = get_cpu();
 
+	info = get_flush_tlb_info(NULL, 0, TLB_FLUSH_ALL, 0, false, 0);
 	if (cpumask_test_cpu(cpu, &batch->cpumask)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
-		flush_tlb_func_local(&full_flush_tlb_info, TLB_LOCAL_SHOOTDOWN);
+		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
 	if (cpumask_any_but(&batch->cpumask, cpu) < nr_cpu_ids)
-		flush_tlb_others(&batch->cpumask, &full_flush_tlb_info);
+		flush_tlb_others(&batch->cpumask, info);
 
 	cpumask_clear(&batch->cpumask);
 
+	put_flush_tlb_info();
 	put_cpu();
 }
 

[tip: x86/mm] smp: Inline on_each_cpu_cond() and on_each_cpu()

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     a5aa5ce300597224ec76dacc8e63ba3ad7a18bbd
Gitweb:        https://git.kernel.org/tip/a5aa5ce300597224ec76dacc8e63ba3ad7a18bbd
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:12 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 06 Mar 2021 12:59:10 +01:00

smp: Inline on_each_cpu_cond() and on_each_cpu()

Simplify the code and avoid having an additional function on the stack
by inlining on_each_cpu_cond() and on_each_cpu().

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
[ Minor edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210220231712.2475218-10-namit@vmware.com
---
 include/linux/smp.h | 50 ++++++++++++++++++++++++++++-----------
 kernel/smp.c        | 56 +--------------------------------------------
 kernel/up.c         | 38 +------------------------------
 3 files changed, 37 insertions(+), 107 deletions(-)

diff --git a/include/linux/smp.h b/include/linux/smp.h
index 70c6f62..84a0b48 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -50,30 +50,52 @@ extern unsigned int total_cpus;
 int smp_call_function_single(int cpuid, smp_call_func_t func, void *info,
 			     int wait);
 
+void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
+			   void *info, bool wait, const struct cpumask *mask);
+
+int smp_call_function_single_async(int cpu, call_single_data_t *csd);
+
 /*
  * Call a function on all processors
  */
-void on_each_cpu(smp_call_func_t func, void *info, int wait);
+static inline void on_each_cpu(smp_call_func_t func, void *info, int wait)
+{
+	on_each_cpu_cond_mask(NULL, func, info, wait, cpu_online_mask);
+}
 
-/*
- * Call a function on processors specified by mask, which might include
- * the local one.
+/**
+ * on_each_cpu_mask(): Run a function on processors specified by
+ * cpumask, which may include the local processor.
+ * @mask: The set of cpus to run on (only runs on online subset).
+ * @func: The function to run. This must be fast and non-blocking.
+ * @info: An arbitrary pointer to pass to the function.
+ * @wait: If true, wait (atomically) until function has completed
+ *        on other CPUs.
+ *
+ * If @wait is true, then returns once @func has returned.
+ *
+ * You must not call this function with disabled interrupts or from a
+ * hardware interrupt handler or from a bottom half handler.  The
+ * exception is that it may be used during early boot while
+ * early_boot_irqs_disabled is set.
  */
-void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
-		void *info, bool wait);
+static inline void on_each_cpu_mask(const struct cpumask *mask,
+				    smp_call_func_t func, void *info, bool wait)
+{
+	on_each_cpu_cond_mask(NULL, func, info, wait, mask);
+}
 
 /*
  * Call a function on each processor for which the supplied function
  * cond_func returns a positive value. This may include the local
- * processor.
+ * processor.  May be used during early boot while early_boot_irqs_disabled is
+ * set. Use local_irq_save/restore() instead of local_irq_disable/enable().
  */
-void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
-		      void *info, bool wait);
-
-void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
-			   void *info, bool wait, const struct cpumask *mask);
-
-int smp_call_function_single_async(int cpu, call_single_data_t *csd);
+static inline void on_each_cpu_cond(smp_cond_func_t cond_func,
+				    smp_call_func_t func, void *info, bool wait)
+{
+	on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
+}
 
 #ifdef CONFIG_SMP
 
diff --git a/kernel/smp.c b/kernel/smp.c
index c8a5a1f..b6375d7 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -848,55 +848,6 @@ void __init smp_init(void)
 }
 
 /*
- * Call a function on all processors.  May be used during early boot while
- * early_boot_irqs_disabled is set.  Use local_irq_save/restore() instead
- * of local_irq_disable/enable().
- */
-void on_each_cpu(smp_call_func_t func, void *info, int wait)
-{
-	unsigned long flags;
-
-	preempt_disable();
-	smp_call_function(func, info, wait);
-	local_irq_save(flags);
-	func(info);
-	local_irq_restore(flags);
-	preempt_enable();
-}
-EXPORT_SYMBOL(on_each_cpu);
-
-/**
- * on_each_cpu_mask(): Run a function on processors specified by
- * cpumask, which may include the local processor.
- * @mask: The set of cpus to run on (only runs on online subset).
- * @func: The function to run. This must be fast and non-blocking.
- * @info: An arbitrary pointer to pass to the function.
- * @wait: If true, wait (atomically) until function has completed
- *        on other CPUs.
- *
- * If @wait is true, then returns once @func has returned.
- *
- * You must not call this function with disabled interrupts or from a
- * hardware interrupt handler or from a bottom half handler.  The
- * exception is that it may be used during early boot while
- * early_boot_irqs_disabled is set.
- */
-void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
-			void *info, bool wait)
-{
-	unsigned int scf_flags;
-
-	scf_flags = SCF_RUN_LOCAL;
-	if (wait)
-		scf_flags |= SCF_WAIT;
-
-	preempt_disable();
-	smp_call_function_many_cond(mask, func, info, scf_flags, NULL);
-	preempt_enable();
-}
-EXPORT_SYMBOL(on_each_cpu_mask);
-
-/*
  * on_each_cpu_cond(): Call a function on each processor for which
  * the supplied function cond_func returns true, optionally waiting
  * for all the required CPUs to finish. This may include the local
@@ -932,13 +883,6 @@ void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 }
 EXPORT_SYMBOL(on_each_cpu_cond_mask);
 
-void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
-		      void *info, bool wait)
-{
-	on_each_cpu_cond_mask(cond_func, func, info, wait, cpu_online_mask);
-}
-EXPORT_SYMBOL(on_each_cpu_cond);
-
 static void do_nothing(void *unused)
 {
 }
diff --git a/kernel/up.c b/kernel/up.c
index c6f323d..bf20b4a 100644
--- a/kernel/up.c
+++ b/kernel/up.c
@@ -36,35 +36,6 @@ int smp_call_function_single_async(int cpu, call_single_data_t *csd)
 }
 EXPORT_SYMBOL(smp_call_function_single_async);
 
-void on_each_cpu(smp_call_func_t func, void *info, int wait)
-{
-	unsigned long flags;
-
-	local_irq_save(flags);
-	func(info);
-	local_irq_restore(flags);
-}
-EXPORT_SYMBOL(on_each_cpu);
-
-/*
- * Note we still need to test the mask even for UP
- * because we actually can get an empty mask from
- * code that on SMP might call us without the local
- * CPU in the mask.
- */
-void on_each_cpu_mask(const struct cpumask *mask,
-		      smp_call_func_t func, void *info, bool wait)
-{
-	unsigned long flags;
-
-	if (cpumask_test_cpu(0, mask)) {
-		local_irq_save(flags);
-		func(info);
-		local_irq_restore(flags);
-	}
-}
-EXPORT_SYMBOL(on_each_cpu_mask);
-
 /*
  * Preemption is disabled here to make sure the cond_func is called under the
  * same condtions in UP and SMP.
@@ -75,7 +46,7 @@ void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 	unsigned long flags;
 
 	preempt_disable();
-	if (cond_func(0, info)) {
+	if ((!cond_func || cond_func(0, info)) && cpumask_test_cpu(0, mask)) {
 		local_irq_save(flags);
 		func(info);
 		local_irq_restore(flags);
@@ -84,13 +55,6 @@ void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 }
 EXPORT_SYMBOL(on_each_cpu_cond_mask);
 
-void on_each_cpu_cond(smp_cond_func_t cond_func, smp_call_func_t func,
-		      void *info, bool wait)
-{
-	on_each_cpu_cond_mask(cond_func, func, info, wait, NULL);
-}
-EXPORT_SYMBOL(on_each_cpu_cond);
-
 int smp_call_on_cpu(unsigned int cpu, int (*func)(void *), void *par, bool phys)
 {
 	int ret;

[tip: x86/mm] x86/mm/tlb: Do not make is_lazy dirty for no reason

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     09c5272e48614a30598e759c3c7bed126d22037d
Gitweb:        https://git.kernel.org/tip/09c5272e48614a30598e759c3c7bed126d22037d
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:09 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 06 Mar 2021 12:59:10 +01:00

x86/mm/tlb: Do not make is_lazy dirty for no reason

Blindly writing to is_lazy for no reason, when the written value is
identical to the old value, makes the cacheline dirty for no reason.
Avoid making such writes to prevent cache coherency traffic for no
reason.

Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-7-namit@vmware.com
---
 arch/x86/mm/tlb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 345a0af..17ec4bf 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -469,7 +469,8 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 		__flush_tlb_all();
 	}
 #endif
-	this_cpu_write(cpu_tlbstate_shared.is_lazy, false);
+	if (was_lazy)
+		this_cpu_write(cpu_tlbstate_shared.is_lazy, false);
 
 	/*
 	 * The membarrier system call requires a full memory barrier and

[tip: x86/mm] cpumask: Mark functions as pure

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     291c4011dd7ac0cd0cebb727a75ee5a50d16dcf7
Gitweb:        https://git.kernel.org/tip/291c4011dd7ac0cd0cebb727a75ee5a50d16dcf7
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:10 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 06 Mar 2021 12:59:10 +01:00

cpumask: Mark functions as pure

cpumask_next_and() and cpumask_any_but() are pure, and marking them as
such seems to generate different and presumably better code for
native_flush_tlb_multi().

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-8-namit@vmware.com
---
 include/linux/cpumask.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 383684e..c53364c 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -235,7 +235,7 @@ static inline unsigned int cpumask_last(const struct cpumask *srcp)
 	return find_last_bit(cpumask_bits(srcp), nr_cpumask_bits);
 }
 
-unsigned int cpumask_next(int n, const struct cpumask *srcp);
+unsigned int __pure cpumask_next(int n, const struct cpumask *srcp);
 
 /**
  * cpumask_next_zero - get the next unset cpu in a cpumask
@@ -252,8 +252,8 @@ static inline unsigned int cpumask_next_zero(int n, const struct cpumask *srcp)
 	return find_next_zero_bit(cpumask_bits(srcp), nr_cpumask_bits, n+1);
 }
 
-int cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
-int cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
+int __pure cpumask_next_and(int n, const struct cpumask *, const struct cpumask *);
+int __pure cpumask_any_but(const struct cpumask *mask, unsigned int cpu);
 unsigned int cpumask_local_spread(unsigned int i, int node);
 int cpumask_any_and_distribute(const struct cpumask *src1p,
 			       const struct cpumask *src2p);

[tip: x86/mm] x86/mm/tlb: Remove unnecessary uses of the inline keyword

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     1608e4cf31b88c8c448ce13aa1d77969dda6bdb7
Gitweb:        https://git.kernel.org/tip/1608e4cf31b88c8c448ce13aa1d77969dda6bdb7
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:11 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 06 Mar 2021 12:59:10 +01:00

x86/mm/tlb: Remove unnecessary uses of the inline keyword

The compiler is smart enough without these hints.

Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-9-namit@vmware.com
---
 arch/x86/mm/tlb.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 17ec4bf..f4b162f 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -316,7 +316,7 @@ void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 	local_irq_restore(flags);
 }
 
-static inline unsigned long mm_mangle_tif_spec_ib(struct task_struct *next)
+static unsigned long mm_mangle_tif_spec_ib(struct task_struct *next)
 {
 	unsigned long next_tif = task_thread_info(next)->flags;
 	unsigned long ibpb = (next_tif >> TIF_SPEC_IB) & LAST_USER_MM_IBPB;
@@ -880,7 +880,7 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct flush_tlb_info, flush_tlb_info);
 static DEFINE_PER_CPU(unsigned int, flush_tlb_info_idx);
 #endif
 
-static inline struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
+static struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
 			unsigned long start, unsigned long end,
 			unsigned int stride_shift, bool freed_tables,
 			u64 new_tlb_gen)
@@ -907,7 +907,7 @@ static inline struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
 	return info;
 }
 
-static inline void put_flush_tlb_info(void)
+static void put_flush_tlb_info(void)
 {
 #ifdef CONFIG_DEBUG_VM
 	/* Complete reentrency prevention checks */

[tip: x86/mm] x86/mm/tlb: Privatize cpu_tlbstate

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     2f4305b19fe6a2a261d76c21856c5598f7d878fe
Gitweb:        https://git.kernel.org/tip/2f4305b19fe6a2a261d76c21856c5598f7d878fe
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:08 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 06 Mar 2021 12:59:10 +01:00

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 <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-6-namit@vmware.com
---
 arch/x86/include/asm/tlbflush.h | 39 +++++++++++++++++---------------
 arch/x86/kernel/alternative.c   |  2 +-
 arch/x86/mm/init.c              |  2 +-
 arch/x86/mm/tlb.c               | 17 ++++++++------
 4 files changed, 33 insertions(+), 27 deletions(-)

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 dd694fb..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)
 {

[tip: x86/mm] x86/mm/tlb: Flush remote and local TLBs concurrently

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     4ce94eabac16b1d2c95762b40f49e5654ab288d7
Gitweb:        https://git.kernel.org/tip/4ce94eabac16b1d2c95762b40f49e5654ab288d7
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:07 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 06 Mar 2021 12:59:10 +01:00

x86/mm/tlb: Flush remote and local TLBs concurrently

To improve TLB shootdown performance, flush the remote and local TLBs
concurrently. Introduce flush_tlb_multi() that does so. Introduce
paravirtual versions of flush_tlb_multi() for KVM, Xen and hyper-v (Xen
and hyper-v are only compile-tested).

While the updated smp infrastructure is capable of running a function on
a single local core, it is not optimized for this case. The multiple
function calls and the indirect branch introduce some overhead, and
might make local TLB flushes slower than they were before the recent
changes.

Before calling the SMP infrastructure, check if only a local TLB flush
is needed to restore the lost performance in this common case. This
requires to check mm_cpumask() one more time, but unless this mask is
updated very frequently, this should impact performance negatively.

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Michael Kelley <mikelley@microsoft.com> # Hyper-v parts
Reviewed-by: Juergen Gross <jgross@suse.com> # Xen and paravirt parts
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-5-namit@vmware.com
---
 arch/x86/hyperv/mmu.c                 | 10 +++---
 arch/x86/include/asm/paravirt.h       |  6 +--
 arch/x86/include/asm/paravirt_types.h |  4 +-
 arch/x86/include/asm/tlbflush.h       |  4 +-
 arch/x86/include/asm/trace/hyperv.h   |  2 +-
 arch/x86/kernel/kvm.c                 | 11 ++++--
 arch/x86/kernel/paravirt.c            |  2 +-
 arch/x86/mm/tlb.c                     | 46 ++++++++++++++++----------
 arch/x86/xen/mmu_pv.c                 | 11 ++----
 include/trace/events/xen.h            |  2 +-
 10 files changed, 57 insertions(+), 41 deletions(-)

diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c
index 2c87350..681dba8 100644
--- a/arch/x86/hyperv/mmu.c
+++ b/arch/x86/hyperv/mmu.c
@@ -52,8 +52,8 @@ static inline int fill_gva_list(u64 gva_list[], int offset,
 	return gva_n - offset;
 }
 
-static void hyperv_flush_tlb_others(const struct cpumask *cpus,
-				    const struct flush_tlb_info *info)
+static void hyperv_flush_tlb_multi(const struct cpumask *cpus,
+				   const struct flush_tlb_info *info)
 {
 	int cpu, vcpu, gva_n, max_gvas;
 	struct hv_tlb_flush **flush_pcpu;
@@ -61,7 +61,7 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
 	u64 status = U64_MAX;
 	unsigned long flags;
 
-	trace_hyperv_mmu_flush_tlb_others(cpus, info);
+	trace_hyperv_mmu_flush_tlb_multi(cpus, info);
 
 	if (!hv_hypercall_pg)
 		goto do_native;
@@ -164,7 +164,7 @@ check_status:
 	if (!(status & HV_HYPERCALL_RESULT_MASK))
 		return;
 do_native:
-	native_flush_tlb_others(cpus, info);
+	native_flush_tlb_multi(cpus, info);
 }
 
 static u64 hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
@@ -239,6 +239,6 @@ void hyperv_setup_mmu_ops(void)
 		return;
 
 	pr_info("Using hypercall for remote TLB flush\n");
-	pv_ops.mmu.flush_tlb_others = hyperv_flush_tlb_others;
+	pv_ops.mmu.flush_tlb_multi = hyperv_flush_tlb_multi;
 	pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 }
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 4abf110..45b55e3 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -50,7 +50,7 @@ static inline void slow_down_io(void)
 void native_flush_tlb_local(void);
 void native_flush_tlb_global(void);
 void native_flush_tlb_one_user(unsigned long addr);
-void native_flush_tlb_others(const struct cpumask *cpumask,
+void native_flush_tlb_multi(const struct cpumask *cpumask,
 			     const struct flush_tlb_info *info);
 
 static inline void __flush_tlb_local(void)
@@ -68,10 +68,10 @@ static inline void __flush_tlb_one_user(unsigned long addr)
 	PVOP_VCALL1(mmu.flush_tlb_one_user, addr);
 }
 
-static inline void __flush_tlb_others(const struct cpumask *cpumask,
+static inline void __flush_tlb_multi(const struct cpumask *cpumask,
 				      const struct flush_tlb_info *info)
 {
-	PVOP_VCALL2(mmu.flush_tlb_others, cpumask, info);
+	PVOP_VCALL2(mmu.flush_tlb_multi, cpumask, info);
 }
 
 static inline void paravirt_tlb_remove_table(struct mmu_gather *tlb, void *table)
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index de87087..b7b35d5 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -188,8 +188,8 @@ struct pv_mmu_ops {
 	void (*flush_tlb_user)(void);
 	void (*flush_tlb_kernel)(void);
 	void (*flush_tlb_one_user)(unsigned long addr);
-	void (*flush_tlb_others)(const struct cpumask *cpus,
-				 const struct flush_tlb_info *info);
+	void (*flush_tlb_multi)(const struct cpumask *cpus,
+				const struct flush_tlb_info *info);
 
 	void (*tlb_remove_table)(struct mmu_gather *tlb, void *table);
 
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index a7a598a..3c6681d 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -175,7 +175,7 @@ extern void initialize_tlbstate_and_flush(void);
  *  - flush_tlb_page(vma, vmaddr) flushes one page
  *  - flush_tlb_range(vma, start, end) flushes a range of pages
  *  - flush_tlb_kernel_range(start, end) flushes a range of kernel pages
- *  - flush_tlb_others(cpumask, info) flushes TLBs on other cpus
+ *  - flush_tlb_multi(cpumask, info) flushes TLBs on multiple cpus
  *
  * ..but the i386 has somewhat limited tlb flushing capabilities,
  * and page-granular flushes are available only on i486 and up.
@@ -209,7 +209,7 @@ struct flush_tlb_info {
 void flush_tlb_local(void);
 void flush_tlb_one_user(unsigned long addr);
 void flush_tlb_one_kernel(unsigned long addr);
-void flush_tlb_others(const struct cpumask *cpumask,
+void flush_tlb_multi(const struct cpumask *cpumask,
 		      const struct flush_tlb_info *info);
 
 #ifdef CONFIG_PARAVIRT
diff --git a/arch/x86/include/asm/trace/hyperv.h b/arch/x86/include/asm/trace/hyperv.h
index 4d705cb..a8e5a7a 100644
--- a/arch/x86/include/asm/trace/hyperv.h
+++ b/arch/x86/include/asm/trace/hyperv.h
@@ -8,7 +8,7 @@
 
 #if IS_ENABLED(CONFIG_HYPERV)
 
-TRACE_EVENT(hyperv_mmu_flush_tlb_others,
+TRACE_EVENT(hyperv_mmu_flush_tlb_multi,
 	    TP_PROTO(const struct cpumask *cpus,
 		     const struct flush_tlb_info *info),
 	    TP_ARGS(cpus, info),
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5e78e01..38ea9de 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -613,7 +613,7 @@ static int kvm_cpu_down_prepare(unsigned int cpu)
 }
 #endif
 
-static void kvm_flush_tlb_others(const struct cpumask *cpumask,
+static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
 			const struct flush_tlb_info *info)
 {
 	u8 state;
@@ -627,6 +627,11 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask,
 	 * queue flush_on_enter for pre-empted vCPUs
 	 */
 	for_each_cpu(cpu, flushmask) {
+		/*
+		 * The local vCPU is never preempted, so we do not explicitly
+		 * skip check for local vCPU - it will never be cleared from
+		 * flushmask.
+		 */
 		src = &per_cpu(steal_time, cpu);
 		state = READ_ONCE(src->preempted);
 		if ((state & KVM_VCPU_PREEMPTED)) {
@@ -636,7 +641,7 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask,
 		}
 	}
 
-	native_flush_tlb_others(flushmask, info);
+	native_flush_tlb_multi(flushmask, info);
 }
 
 static void __init kvm_guest_init(void)
@@ -654,7 +659,7 @@ static void __init kvm_guest_init(void)
 	}
 
 	if (pv_tlb_flush_supported()) {
-		pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
+		pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
 		pv_ops.mmu.tlb_remove_table = tlb_remove_table;
 		pr_info("KVM setup pv remote TLB flush\n");
 	}
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index c60222a..197a126 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -330,7 +330,7 @@ struct paravirt_patch_template pv_ops = {
 	.mmu.flush_tlb_user	= native_flush_tlb_local,
 	.mmu.flush_tlb_kernel	= native_flush_tlb_global,
 	.mmu.flush_tlb_one_user	= native_flush_tlb_one_user,
-	.mmu.flush_tlb_others	= native_flush_tlb_others,
+	.mmu.flush_tlb_multi	= native_flush_tlb_multi,
 	.mmu.tlb_remove_table	=
 			(void (*)(struct mmu_gather *, void *))tlb_remove_page,
 
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 07b6701..8db87cd 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -24,7 +24,7 @@
 # define __flush_tlb_local		native_flush_tlb_local
 # define __flush_tlb_global		native_flush_tlb_global
 # define __flush_tlb_one_user(addr)	native_flush_tlb_one_user(addr)
-# define __flush_tlb_others(msk, info)	native_flush_tlb_others(msk, info)
+# define __flush_tlb_multi(msk, info)	native_flush_tlb_multi(msk, info)
 #endif
 
 /*
@@ -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
-		 * from cpu_tlbstate.is_lazy whether or not to send an IPI.
+		 * cpu_tlbstate.is_lazy whether or not to send an IPI.
 		 */
 		if (WARN_ON_ONCE(real_prev != &init_mm &&
 				 !cpumask_test_cpu(cpu, mm_cpumask(next))))
@@ -697,7 +697,7 @@ static void flush_tlb_func(void *info)
 		 * garbage into our TLB.  Since switching to init_mm is barely
 		 * slower than a minimal flush, just switch to init_mm.
 		 *
-		 * This should be rare, with native_flush_tlb_others skipping
+		 * This should be rare, with native_flush_tlb_multi() skipping
 		 * IPIs to lazy TLB mode CPUs.
 		 */
 		switch_mm_irqs_off(NULL, &init_mm, NULL);
@@ -795,9 +795,14 @@ static bool tlb_is_not_lazy(int cpu)
 
 static DEFINE_PER_CPU(cpumask_t, flush_tlb_mask);
 
-STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
+STATIC_NOPV void native_flush_tlb_multi(const struct cpumask *cpumask,
 					 const struct flush_tlb_info *info)
 {
+	/*
+	 * Do accounting and tracing. Note that there are (and have always been)
+	 * cases in which a remote TLB flush will be traced, but eventually
+	 * would not happen.
+	 */
 	count_vm_tlb_event(NR_TLB_REMOTE_FLUSH);
 	if (info->end == TLB_FLUSH_ALL)
 		trace_tlb_flush(TLB_REMOTE_SEND_IPI, TLB_FLUSH_ALL);
@@ -816,8 +821,7 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 	 * doing a speculative memory access.
 	 */
 	if (info->freed_tables) {
-		smp_call_function_many(cpumask, flush_tlb_func,
-			       (void *)info, 1);
+		on_each_cpu_mask(cpumask, flush_tlb_func, (void *)info, true);
 	} else {
 		/*
 		 * Although we could have used on_each_cpu_cond_mask(),
@@ -844,14 +848,14 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 			if (tlb_is_not_lazy(cpu))
 				__cpumask_set_cpu(cpu, cond_cpumask);
 		}
-		smp_call_function_many(cond_cpumask, flush_tlb_func, (void *)info, 1);
+		on_each_cpu_mask(cond_cpumask, flush_tlb_func, (void *)info, true);
 	}
 }
 
-void flush_tlb_others(const struct cpumask *cpumask,
+void flush_tlb_multi(const struct cpumask *cpumask,
 		      const struct flush_tlb_info *info)
 {
-	__flush_tlb_others(cpumask, info);
+	__flush_tlb_multi(cpumask, info);
 }
 
 /*
@@ -931,16 +935,20 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 	info = get_flush_tlb_info(mm, start, end, stride_shift, freed_tables,
 				  new_tlb_gen);
 
-	if (mm == this_cpu_read(cpu_tlbstate.loaded_mm)) {
+	/*
+	 * flush_tlb_multi() is not optimized for the common case in which only
+	 * a local TLB flush is needed. Optimize this use-case by calling
+	 * flush_tlb_func_local() directly in this case.
+	 */
+	if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids) {
+		flush_tlb_multi(mm_cpumask(mm), info);
+	} else if (mm == this_cpu_read(cpu_tlbstate.loaded_mm)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
 		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
-	if (cpumask_any_but(mm_cpumask(mm), cpu) < nr_cpu_ids)
-		flush_tlb_others(mm_cpumask(mm), info);
-
 	put_flush_tlb_info();
 	put_cpu();
 }
@@ -1152,16 +1160,20 @@ void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
 	int cpu = get_cpu();
 
 	info = get_flush_tlb_info(NULL, 0, TLB_FLUSH_ALL, 0, false, 0);
-	if (cpumask_test_cpu(cpu, &batch->cpumask)) {
+	/*
+	 * flush_tlb_multi() is not optimized for the common case in which only
+	 * a local TLB flush is needed. Optimize this use-case by calling
+	 * flush_tlb_func_local() directly in this case.
+	 */
+	if (cpumask_any_but(&batch->cpumask, cpu) < nr_cpu_ids) {
+		flush_tlb_multi(&batch->cpumask, info);
+	} else if (cpumask_test_cpu(cpu, &batch->cpumask)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
 		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
-	if (cpumask_any_but(&batch->cpumask, cpu) < nr_cpu_ids)
-		flush_tlb_others(&batch->cpumask, info);
-
 	cpumask_clear(&batch->cpumask);
 
 	put_flush_tlb_info();
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index cf2ade8..09b95c0 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -1247,8 +1247,8 @@ static void xen_flush_tlb_one_user(unsigned long addr)
 	preempt_enable();
 }
 
-static void xen_flush_tlb_others(const struct cpumask *cpus,
-				 const struct flush_tlb_info *info)
+static void xen_flush_tlb_multi(const struct cpumask *cpus,
+				const struct flush_tlb_info *info)
 {
 	struct {
 		struct mmuext_op op;
@@ -1258,7 +1258,7 @@ static void xen_flush_tlb_others(const struct cpumask *cpus,
 	const size_t mc_entry_size = sizeof(args->op) +
 		sizeof(args->mask[0]) * BITS_TO_LONGS(num_possible_cpus());
 
-	trace_xen_mmu_flush_tlb_others(cpus, info->mm, info->start, info->end);
+	trace_xen_mmu_flush_tlb_multi(cpus, info->mm, info->start, info->end);
 
 	if (cpumask_empty(cpus))
 		return;		/* nothing to do */
@@ -1267,9 +1267,8 @@ static void xen_flush_tlb_others(const struct cpumask *cpus,
 	args = mcs.args;
 	args->op.arg2.vcpumask = to_cpumask(args->mask);
 
-	/* Remove us, and any offline CPUS. */
+	/* Remove any offline CPUs */
 	cpumask_and(to_cpumask(args->mask), cpus, cpu_online_mask);
-	cpumask_clear_cpu(smp_processor_id(), to_cpumask(args->mask));
 
 	args->op.cmd = MMUEXT_TLB_FLUSH_MULTI;
 	if (info->end != TLB_FLUSH_ALL &&
@@ -2086,7 +2085,7 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = {
 	.flush_tlb_user = xen_flush_tlb,
 	.flush_tlb_kernel = xen_flush_tlb,
 	.flush_tlb_one_user = xen_flush_tlb_one_user,
-	.flush_tlb_others = xen_flush_tlb_others,
+	.flush_tlb_multi = xen_flush_tlb_multi,
 	.tlb_remove_table = tlb_remove_table,
 
 	.pgd_alloc = xen_pgd_alloc,
diff --git a/include/trace/events/xen.h b/include/trace/events/xen.h
index 3b61b58..44a3f56 100644
--- a/include/trace/events/xen.h
+++ b/include/trace/events/xen.h
@@ -346,7 +346,7 @@ TRACE_EVENT(xen_mmu_flush_tlb_one_user,
 	    TP_printk("addr %lx", __entry->addr)
 	);
 
-TRACE_EVENT(xen_mmu_flush_tlb_others,
+TRACE_EVENT(xen_mmu_flush_tlb_multi,
 	    TP_PROTO(const struct cpumask *cpus, struct mm_struct *mm,
 		     unsigned long addr, unsigned long end),
 	    TP_ARGS(cpus, mm, addr, end),

[tip: x86/mm] x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy()

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     6035152d8eebe16a5bb60398d3e05dc7799067b0
Gitweb:        https://git.kernel.org/tip/6035152d8eebe16a5bb60398d3e05dc7799067b0
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:06 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 06 Mar 2021 12:59:09 +01:00

x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy()

Open-code on_each_cpu_cond_mask() in native_flush_tlb_others() to
optimize the code. Open-coding eliminates the need for the indirect branch
that is used to call is_lazy(), and in CPUs that are vulnerable to
Spectre v2, it eliminates the retpoline. In addition, it allows to use a
preallocated cpumask to compute the CPUs that should be.

This would later allow us not to adapt on_each_cpu_cond_mask() to
support local and remote functions.

Note that calling tlb_is_not_lazy() for every CPU that needs to be
flushed, as done in native_flush_tlb_multi() might look ugly, but it is
equivalent to what is currently done in on_each_cpu_cond_mask().
Actually, native_flush_tlb_multi() does it more efficiently since it
avoids using an indirect branch for the matter.

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-4-namit@vmware.com
---
 arch/x86/mm/tlb.c | 37 ++++++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index bf12371..07b6701 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -788,11 +788,13 @@ done:
 			nr_invalidate);
 }
 
-static bool tlb_is_not_lazy(int cpu, void *data)
+static bool tlb_is_not_lazy(int cpu)
 {
 	return !per_cpu(cpu_tlbstate.is_lazy, cpu);
 }
 
+static DEFINE_PER_CPU(cpumask_t, flush_tlb_mask);
+
 STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 					 const struct flush_tlb_info *info)
 {
@@ -813,12 +815,37 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 	 * up on the new contents of what used to be page tables, while
 	 * doing a speculative memory access.
 	 */
-	if (info->freed_tables)
+	if (info->freed_tables) {
 		smp_call_function_many(cpumask, flush_tlb_func,
 			       (void *)info, 1);
-	else
-		on_each_cpu_cond_mask(tlb_is_not_lazy, flush_tlb_func,
-				(void *)info, 1, cpumask);
+	} else {
+		/*
+		 * Although we could have used on_each_cpu_cond_mask(),
+		 * open-coding it has performance advantages, as it eliminates
+		 * the need for indirect calls or retpolines. In addition, it
+		 * allows to use a designated cpumask for evaluating the
+		 * condition, instead of allocating one.
+		 *
+		 * This code works under the assumption that there are no nested
+		 * TLB flushes, an assumption that is already made in
+		 * flush_tlb_mm_range().
+		 *
+		 * cond_cpumask is logically a stack-local variable, but it is
+		 * more efficient to have it off the stack and not to allocate
+		 * it on demand. Preemption is disabled and this code is
+		 * non-reentrant.
+		 */
+		struct cpumask *cond_cpumask = this_cpu_ptr(&flush_tlb_mask);
+		int cpu;
+
+		cpumask_clear(cond_cpumask);
+
+		for_each_cpu(cpu, cpumask) {
+			if (tlb_is_not_lazy(cpu))
+				__cpumask_set_cpu(cpu, cond_cpumask);
+		}
+		smp_call_function_many(cond_cpumask, flush_tlb_func, (void *)info, 1);
+	}
 }
 
 void flush_tlb_others(const struct cpumask *cpumask,

[tip: x86/mm] smp: Run functions concurrently in smp_call_function_many_cond()

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     a32a4d8a815c4eb6dc64b8962dc13a9dfae70868
Gitweb:        https://git.kernel.org/tip/a32a4d8a815c4eb6dc64b8962dc13a9dfae70868
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:04 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 06 Mar 2021 12:59:09 +01:00

smp: Run functions concurrently in smp_call_function_many_cond()

Currently, on_each_cpu() and similar functions do not exploit the
potential of concurrency: the function is first executed remotely and
only then it is executed locally. Functions such as TLB flush can take
considerable time, so this provides an opportunity for performance
optimization.

To do so, modify smp_call_function_many_cond(), to allows the callers to
provide a function that should be executed (remotely/locally), and run
them concurrently. Keep other smp_call_function_many() semantic as it is
today for backward compatibility: the called function is not executed in
this case locally.

smp_call_function_many_cond() does not use the optimized version for a
single remote target that smp_call_function_single() implements. For
synchronous function call, smp_call_function_single() keeps a
call_single_data (which is used for synchronization) on the stack.
Interestingly, it seems that not using this optimization provides
greater performance improvements (greater speedup with a single remote
target than with multiple ones). Presumably, holding data structures
that are intended for synchronization on the stack can introduce
overheads due to TLB misses and false-sharing when the stack is used for
other purposes.

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-2-namit@vmware.com
---
 kernel/smp.c | 156 ++++++++++++++++++++++++++++----------------------
 1 file changed, 88 insertions(+), 68 deletions(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index aeb0adf..c8a5a1f 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -608,12 +608,28 @@ call:
 }
 EXPORT_SYMBOL_GPL(smp_call_function_any);
 
+/*
+ * Flags to be used as scf_flags argument of smp_call_function_many_cond().
+ *
+ * %SCF_WAIT:		Wait until function execution is completed
+ * %SCF_RUN_LOCAL:	Run also locally if local cpu is set in cpumask
+ */
+#define SCF_WAIT	(1U << 0)
+#define SCF_RUN_LOCAL	(1U << 1)
+
 static void smp_call_function_many_cond(const struct cpumask *mask,
 					smp_call_func_t func, void *info,
-					bool wait, smp_cond_func_t cond_func)
+					unsigned int scf_flags,
+					smp_cond_func_t cond_func)
 {
+	int cpu, last_cpu, this_cpu = smp_processor_id();
 	struct call_function_data *cfd;
-	int cpu, next_cpu, this_cpu = smp_processor_id();
+	bool wait = scf_flags & SCF_WAIT;
+	bool run_remote = false;
+	bool run_local = false;
+	int nr_cpus = 0;
+
+	lockdep_assert_preemption_disabled();
 
 	/*
 	 * Can deadlock when called with interrupts disabled.
@@ -621,8 +637,9 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 	 * send smp call function interrupt to this cpu and as such deadlocks
 	 * can't happen.
 	 */
-	WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
-		     && !oops_in_progress && !early_boot_irqs_disabled);
+	if (cpu_online(this_cpu) && !oops_in_progress &&
+	    !early_boot_irqs_disabled)
+		lockdep_assert_irqs_enabled();
 
 	/*
 	 * When @wait we can deadlock when we interrupt between llist_add() and
@@ -632,60 +649,65 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 	 */
 	WARN_ON_ONCE(!in_task());
 
-	/* Try to fastpath.  So, what's a CPU they want? Ignoring this one. */
+	/* Check if we need local execution. */
+	if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(this_cpu, mask))
+		run_local = true;
+
+	/* Check if we need remote execution, i.e., any CPU excluding this one. */
 	cpu = cpumask_first_and(mask, cpu_online_mask);
 	if (cpu == this_cpu)
 		cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
+	if (cpu < nr_cpu_ids)
+		run_remote = true;
 
-	/* No online cpus?  We're done. */
-	if (cpu >= nr_cpu_ids)
-		return;
-
-	/* Do we have another CPU which isn't us? */
-	next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
-	if (next_cpu == this_cpu)
-		next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
-
-	/* Fastpath: do that cpu by itself. */
-	if (next_cpu >= nr_cpu_ids) {
-		if (!cond_func || cond_func(cpu, info))
-			smp_call_function_single(cpu, func, info, wait);
-		return;
-	}
-
-	cfd = this_cpu_ptr(&cfd_data);
+	if (run_remote) {
+		cfd = this_cpu_ptr(&cfd_data);
+		cpumask_and(cfd->cpumask, mask, cpu_online_mask);
+		__cpumask_clear_cpu(this_cpu, cfd->cpumask);
 
-	cpumask_and(cfd->cpumask, mask, cpu_online_mask);
-	__cpumask_clear_cpu(this_cpu, cfd->cpumask);
-
-	/* Some callers race with other cpus changing the passed mask */
-	if (unlikely(!cpumask_weight(cfd->cpumask)))
-		return;
+		cpumask_clear(cfd->cpumask_ipi);
+		for_each_cpu(cpu, cfd->cpumask) {
+			call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
 
-	cpumask_clear(cfd->cpumask_ipi);
-	for_each_cpu(cpu, cfd->cpumask) {
-		call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);
+			if (cond_func && !cond_func(cpu, info))
+				continue;
 
-		if (cond_func && !cond_func(cpu, info))
-			continue;
-
-		csd_lock(csd);
-		if (wait)
-			csd->node.u_flags |= CSD_TYPE_SYNC;
-		csd->func = func;
-		csd->info = info;
+			csd_lock(csd);
+			if (wait)
+				csd->node.u_flags |= CSD_TYPE_SYNC;
+			csd->func = func;
+			csd->info = info;
 #ifdef CONFIG_CSD_LOCK_WAIT_DEBUG
-		csd->node.src = smp_processor_id();
-		csd->node.dst = cpu;
+			csd->node.src = smp_processor_id();
+			csd->node.dst = cpu;
 #endif
-		if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu)))
-			__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
+			if (llist_add(&csd->node.llist, &per_cpu(call_single_queue, cpu))) {
+				__cpumask_set_cpu(cpu, cfd->cpumask_ipi);
+				nr_cpus++;
+				last_cpu = cpu;
+			}
+		}
+
+		/*
+		 * Choose the most efficient way to send an IPI. Note that the
+		 * number of CPUs might be zero due to concurrent changes to the
+		 * provided mask.
+		 */
+		if (nr_cpus == 1)
+			arch_send_call_function_single_ipi(last_cpu);
+		else if (likely(nr_cpus > 1))
+			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
 	}
 
-	/* Send a message to all CPUs in the map */
-	arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
+	if (run_local && (!cond_func || cond_func(this_cpu, info))) {
+		unsigned long flags;
 
-	if (wait) {
+		local_irq_save(flags);
+		func(info);
+		local_irq_restore(flags);
+	}
+
+	if (run_remote && wait) {
 		for_each_cpu(cpu, cfd->cpumask) {
 			call_single_data_t *csd;
 
@@ -696,12 +718,14 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 }
 
 /**
- * smp_call_function_many(): Run a function on a set of other CPUs.
+ * smp_call_function_many(): Run a function on a set of CPUs.
  * @mask: The set of cpus to run on (only runs on online subset).
  * @func: The function to run. This must be fast and non-blocking.
  * @info: An arbitrary pointer to pass to the function.
- * @wait: If true, wait (atomically) until function has completed
- *        on other CPUs.
+ * @flags: Bitmask that controls the operation. If %SCF_WAIT is set, wait
+ *        (atomically) until function has completed on other CPUs. If
+ *        %SCF_RUN_LOCAL is set, the function will also be run locally
+ *        if the local CPU is set in the @cpumask.
  *
  * If @wait is true, then returns once @func has returned.
  *
@@ -712,7 +736,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 void smp_call_function_many(const struct cpumask *mask,
 			    smp_call_func_t func, void *info, bool wait)
 {
-	smp_call_function_many_cond(mask, func, info, wait, NULL);
+	smp_call_function_many_cond(mask, func, info, wait * SCF_WAIT, NULL);
 }
 EXPORT_SYMBOL(smp_call_function_many);
 
@@ -860,16 +884,15 @@ EXPORT_SYMBOL(on_each_cpu);
 void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
 			void *info, bool wait)
 {
-	int cpu = get_cpu();
+	unsigned int scf_flags;
 
-	smp_call_function_many(mask, func, info, wait);
-	if (cpumask_test_cpu(cpu, mask)) {
-		unsigned long flags;
-		local_irq_save(flags);
-		func(info);
-		local_irq_restore(flags);
-	}
-	put_cpu();
+	scf_flags = SCF_RUN_LOCAL;
+	if (wait)
+		scf_flags |= SCF_WAIT;
+
+	preempt_disable();
+	smp_call_function_many_cond(mask, func, info, scf_flags, NULL);
+	preempt_enable();
 }
 EXPORT_SYMBOL(on_each_cpu_mask);
 
@@ -898,17 +921,14 @@ EXPORT_SYMBOL(on_each_cpu_mask);
 void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 			   void *info, bool wait, const struct cpumask *mask)
 {
-	int cpu = get_cpu();
+	unsigned int scf_flags = SCF_RUN_LOCAL;
 
-	smp_call_function_many_cond(mask, func, info, wait, cond_func);
-	if (cpumask_test_cpu(cpu, mask) && cond_func(cpu, info)) {
-		unsigned long flags;
+	if (wait)
+		scf_flags |= SCF_WAIT;
 
-		local_irq_save(flags);
-		func(info);
-		local_irq_restore(flags);
-	}
-	put_cpu();
+	preempt_disable();
+	smp_call_function_many_cond(mask, func, info, scf_flags, cond_func);
+	preempt_enable();
 }
 EXPORT_SYMBOL(on_each_cpu_cond_mask);
 

[tip: x86/mm] x86/mm/tlb: Unify flush_tlb_func_local() and flush_tlb_func_remote()

[tip-bot2 for Nadav Amit]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     4c1ba3923e6c8aa736e40f481a278c21b956c072
Gitweb:        https://git.kernel.org/tip/4c1ba3923e6c8aa736e40f481a278c21b956c072
Author:        Nadav Amit <namit@vmware.com>
AuthorDate:    Sat, 20 Feb 2021 15:17:05 -08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 06 Mar 2021 12:59:09 +01:00

x86/mm/tlb: Unify flush_tlb_func_local() and flush_tlb_func_remote()

The unification of these two functions allows to use them in the updated
SMP infrastrucutre.

To do so, remove the reason argument from flush_tlb_func_local(), add
a member to struct tlb_flush_info that says which CPU initiated the
flush and act accordingly. Optimize the size of flush_tlb_info while we
are at it.

Unfortunately, this prevents us from using a constant tlb_flush_info for
arch_tlbbatch_flush(), but in a later stage we may be able to inline
tlb_flush_info into the IPI data, so it should not have an impact
eventually.

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20210220231712.2475218-3-namit@vmware.com
---
 arch/x86/include/asm/tlbflush.h |  5 +-
 arch/x86/mm/tlb.c               | 81 ++++++++++++++------------------
 2 files changed, 39 insertions(+), 47 deletions(-)

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 8c87a2e..a7a598a 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -201,8 +201,9 @@ struct flush_tlb_info {
 	unsigned long		start;
 	unsigned long		end;
 	u64			new_tlb_gen;
-	unsigned int		stride_shift;
-	bool			freed_tables;
+	unsigned int		initiating_cpu;
+	u8			stride_shift;
+	u8			freed_tables;
 };
 
 void flush_tlb_local(void);
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 569ac1d..bf12371 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -439,7 +439,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 	 * NB: leave_mm() calls us with prev == NULL and tsk == NULL.
 	 */
 
-	/* We don't want flush_tlb_func_* to run concurrently with us. */
+	/* We don't want flush_tlb_func() to run concurrently with us. */
 	if (IS_ENABLED(CONFIG_PROVE_LOCKING))
 		WARN_ON_ONCE(!irqs_disabled());
 
@@ -647,14 +647,13 @@ void initialize_tlbstate_and_flush(void)
 }
 
 /*
- * flush_tlb_func_common()'s memory ordering requirement is that any
+ * flush_tlb_func()'s memory ordering requirement is that any
  * TLB fills that happen after we flush the TLB are ordered after we
  * read active_mm's tlb_gen.  We don't need any explicit barriers
  * because all x86 flush operations are serializing and the
  * atomic64_read operation won't be reordered by the compiler.
  */
-static void flush_tlb_func_common(const struct flush_tlb_info *f,
-				  bool local, enum tlb_flush_reason reason)
+static void flush_tlb_func(void *info)
 {
 	/*
 	 * We have three different tlb_gen values in here.  They are:
@@ -665,14 +664,26 @@ static void flush_tlb_func_common(const struct flush_tlb_info *f,
 	 * - f->new_tlb_gen: the generation that the requester of the flush
 	 *                   wants us to catch up to.
 	 */
+	const struct flush_tlb_info *f = info;
 	struct mm_struct *loaded_mm = this_cpu_read(cpu_tlbstate.loaded_mm);
 	u32 loaded_mm_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid);
 	u64 mm_tlb_gen = atomic64_read(&loaded_mm->context.tlb_gen);
 	u64 local_tlb_gen = this_cpu_read(cpu_tlbstate.ctxs[loaded_mm_asid].tlb_gen);
+	bool local = smp_processor_id() == f->initiating_cpu;
+	unsigned long nr_invalidate = 0;
 
 	/* This code cannot presently handle being reentered. */
 	VM_WARN_ON(!irqs_disabled());
 
+	if (!local) {
+		inc_irq_stat(irq_tlb_count);
+		count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
+
+		/* Can only happen on remote CPUs */
+		if (f->mm && f->mm != loaded_mm)
+			return;
+	}
+
 	if (unlikely(loaded_mm == &init_mm))
 		return;
 
@@ -700,8 +711,7 @@ static void flush_tlb_func_common(const struct flush_tlb_info *f,
 		 * be handled can catch us all the way up, leaving no work for
 		 * the second flush.
 		 */
-		trace_tlb_flush(reason, 0);
-		return;
+		goto done;
 	}
 
 	WARN_ON_ONCE(local_tlb_gen > mm_tlb_gen);
@@ -748,46 +758,34 @@ static void flush_tlb_func_common(const struct flush_tlb_info *f,
 	    f->new_tlb_gen == local_tlb_gen + 1 &&
 	    f->new_tlb_gen == mm_tlb_gen) {
 		/* Partial flush */
-		unsigned long nr_invalidate = (f->end - f->start) >> f->stride_shift;
 		unsigned long addr = f->start;
 
+		nr_invalidate = (f->end - f->start) >> f->stride_shift;
+
 		while (addr < f->end) {
 			flush_tlb_one_user(addr);
 			addr += 1UL << f->stride_shift;
 		}
 		if (local)
 			count_vm_tlb_events(NR_TLB_LOCAL_FLUSH_ONE, nr_invalidate);
-		trace_tlb_flush(reason, nr_invalidate);
 	} else {
 		/* Full flush. */
+		nr_invalidate = TLB_FLUSH_ALL;
+
 		flush_tlb_local();
 		if (local)
 			count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
-		trace_tlb_flush(reason, TLB_FLUSH_ALL);
 	}
 
 	/* Both paths above update our state to mm_tlb_gen. */
 	this_cpu_write(cpu_tlbstate.ctxs[loaded_mm_asid].tlb_gen, mm_tlb_gen);
-}
-
-static void flush_tlb_func_local(const void *info, enum tlb_flush_reason reason)
-{
-	const struct flush_tlb_info *f = info;
-
-	flush_tlb_func_common(f, true, reason);
-}
 
-static void flush_tlb_func_remote(void *info)
-{
-	const struct flush_tlb_info *f = info;
-
-	inc_irq_stat(irq_tlb_count);
-
-	if (f->mm && f->mm != this_cpu_read(cpu_tlbstate.loaded_mm))
-		return;
-
-	count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
-	flush_tlb_func_common(f, false, TLB_REMOTE_SHOOTDOWN);
+	/* Tracing is done in a unified manner to reduce the code size */
+done:
+	trace_tlb_flush(!local ? TLB_REMOTE_SHOOTDOWN :
+				(f->mm == NULL) ? TLB_LOCAL_SHOOTDOWN :
+						  TLB_LOCAL_MM_SHOOTDOWN,
+			nr_invalidate);
 }
 
 static bool tlb_is_not_lazy(int cpu, void *data)
@@ -816,10 +814,10 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
 	 * doing a speculative memory access.
 	 */
 	if (info->freed_tables)
-		smp_call_function_many(cpumask, flush_tlb_func_remote,
+		smp_call_function_many(cpumask, flush_tlb_func,
 			       (void *)info, 1);
 	else
-		on_each_cpu_cond_mask(tlb_is_not_lazy, flush_tlb_func_remote,
+		on_each_cpu_cond_mask(tlb_is_not_lazy, flush_tlb_func,
 				(void *)info, 1, cpumask);
 }
 
@@ -869,6 +867,7 @@ static inline struct flush_tlb_info *get_flush_tlb_info(struct mm_struct *mm,
 	info->stride_shift	= stride_shift;
 	info->freed_tables	= freed_tables;
 	info->new_tlb_gen	= new_tlb_gen;
+	info->initiating_cpu	= smp_processor_id();
 
 	return info;
 }
@@ -908,7 +907,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 	if (mm == this_cpu_read(cpu_tlbstate.loaded_mm)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
-		flush_tlb_func_local(info, TLB_LOCAL_MM_SHOOTDOWN);
+		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
@@ -1119,34 +1118,26 @@ void __flush_tlb_all(void)
 }
 EXPORT_SYMBOL_GPL(__flush_tlb_all);
 
-/*
- * arch_tlbbatch_flush() performs a full TLB flush regardless of the active mm.
- * This means that the 'struct flush_tlb_info' that describes which mappings to
- * flush is actually fixed. We therefore set a single fixed struct and use it in
- * arch_tlbbatch_flush().
- */
-static const struct flush_tlb_info full_flush_tlb_info = {
-	.mm = NULL,
-	.start = 0,
-	.end = TLB_FLUSH_ALL,
-};
-
 void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
 {
+	struct flush_tlb_info *info;
+
 	int cpu = get_cpu();
 
+	info = get_flush_tlb_info(NULL, 0, TLB_FLUSH_ALL, 0, false, 0);
 	if (cpumask_test_cpu(cpu, &batch->cpumask)) {
 		lockdep_assert_irqs_enabled();
 		local_irq_disable();
-		flush_tlb_func_local(&full_flush_tlb_info, TLB_LOCAL_SHOOTDOWN);
+		flush_tlb_func(info);
 		local_irq_enable();
 	}
 
 	if (cpumask_any_but(&batch->cpumask, cpu) < nr_cpu_ids)
-		flush_tlb_others(&batch->cpumask, &full_flush_tlb_info);
+		flush_tlb_others(&batch->cpumask, info);
 
 	cpumask_clear(&batch->cpumask);
 
+	put_flush_tlb_info();
 	put_cpu();
 }