linux-kernel - [RFC PATCH v2 9/9] riscv: mm: Clear mm_cpumask during local_flush_tlb

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Message-ID: <20251127141117.87420-10-luxu.kernel@bytedance.com>
Date: Thu, 27 Nov 2025 22:11:17 +0800
From: Xu Lu <luxu.kernel@...edance.com>
To: pjw@...nel.org,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	alex@...ti.fr,
	kees@...nel.org,
	mingo@...hat.com,
	peterz@...radead.org,
	juri.lelli@...hat.com,
	vincent.guittot@...aro.org,
	akpm@...ux-foundation.org,
	david@...hat.com,
	apatel@...tanamicro.com,
	guoren@...nel.org
Cc: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	Xu Lu <luxu.kernel@...edance.com>
Subject: [RFC PATCH v2 9/9] riscv: mm: Clear mm_cpumask during local_flush_tlb_all()

Now that we maintain an array of active mms on each CPU, when
local_flush_tlb_all() is called, we can clear current CPU in the
mm_cpumask of all active mms on current CPU.

Signed-off-by: Xu Lu <luxu.kernel@...edance.com>
---
 arch/riscv/include/asm/tlbflush.h |  6 ++++++
 arch/riscv/mm/context.c           |  2 +-
 arch/riscv/mm/tlbflush.c          | 31 +++++++++++++++++++++++++++++--
 3 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
index c9630267c58cd..fd62b27172d4a 100644
--- a/arch/riscv/include/asm/tlbflush.h
+++ b/arch/riscv/include/asm/tlbflush.h
@@ -108,6 +108,7 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_info, tlbinfo);
 
 void local_load_tlb_mm(struct mm_struct *mm);
 void local_flush_tlb_mm(struct mm_struct *mm);
+void local_flush_tlb_all_mm(void);
 void __init lazy_tlb_flush_init(void);
 
 #else /* CONFIG_RISCV_LAZY_TLB_FLUSH */
@@ -119,6 +120,11 @@ static inline void local_flush_tlb_mm(struct mm_struct *mm)
 	local_flush_tlb_all_asid(get_mm_asid(mm));
 }
 
+static inline void local_flush_tlb_all_mm(void)
+{
+	local_flush_tlb_all();
+}
+
 static inline void lazy_tlb_flush_init(void) {}
 
 #endif /* CONFIG_RISCV_LAZY_TLB_FLUSH */
diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
index c381c4ed46bfb..b6657681948f9 100644
--- a/arch/riscv/mm/context.c
+++ b/arch/riscv/mm/context.c
@@ -194,7 +194,7 @@ static void set_mm_asid(struct mm_struct *mm, unsigned int cpu)
 		  satp_mode);
 
 	if (need_flush_tlb)
-		local_flush_tlb_all();
+		local_flush_tlb_all_mm();
 }
 
 static void set_mm_noasid(struct mm_struct *mm)
diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index 88a1e45bcf508..73c0a7ef61cb1 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -89,13 +89,13 @@ void local_flush_tlb_kernel_range(unsigned long start, unsigned long end)
 
 static void __ipi_flush_tlb_all(void *info)
 {
-	local_flush_tlb_all();
+	local_flush_tlb_all_mm();
 }
 
 void flush_tlb_all(void)
 {
 	if (num_online_cpus() < 2)
-		local_flush_tlb_all();
+		local_flush_tlb_all_mm();
 	else if (riscv_use_sbi_for_rfence())
 		sbi_remote_sfence_vma_asid(NULL, 0, FLUSH_TLB_MAX_SIZE, FLUSH_TLB_NO_ASID);
 	else
@@ -461,6 +461,33 @@ void local_flush_tlb_mm(struct mm_struct *mm)
 	local_flush_tlb_all_asid(asid);
 }
 
+void local_flush_tlb_all_mm(void)
+{
+	struct tlb_info *info = this_cpu_ptr(&tlbinfo);
+	struct tlb_context *contexts = info->contexts;
+	struct mm_struct *mms[MAX_LOADED_MM];
+	unsigned int cpu = raw_smp_processor_id();
+	unsigned int i, num = 0;
+
+	write_lock(&info->rwlock);
+	for (i = 0; i < MAX_LOADED_MM; i++) {
+		if (!contexts[i].mm || contexts[i].mm == info->active_mm)
+			continue;
+
+		mms[num++] = contexts[i].mm;
+		contexts[i].mm = NULL;
+		contexts[i].gen = 0;
+	}
+	write_unlock(&info->rwlock);
+
+	for (i = 0; i < num; i++) {
+		cpumask_clear_cpu(cpu, mm_cpumask(mms[i]));
+		mmdrop_lazy_mm(mms[i]);
+	}
+
+	local_flush_tlb_all();
+}
+
 void __init lazy_tlb_flush_init(void)
 {
 	struct tlb_flush_queue *queue;
-- 
2.20.1