From 038ac18aae935c89c874649acde5a82f588a12b4 Mon Sep 17 00:00:00 2001 From: Samuel Holland Date: Tue, 26 Mar 2024 21:49:45 -0700 Subject: [PATCH] riscv: mm: Broadcast kernel TLB flushes only when needed __flush_tlb_range() avoids broadcasting TLB flushes when an mm context is only active on the local CPU. Apply this same optimization to TLB flushes of kernel memory when only one CPU is online. This check can be constant-folded when SMP is disabled. Reviewed-by: Alexandre Ghiti Signed-off-by: Samuel Holland Link: https://lore.kernel.org/r/20240327045035.368512-5-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/mm/tlbflush.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c index 0435605b07d0b..da821315d43ee 100644 --- a/arch/riscv/mm/tlbflush.c +++ b/arch/riscv/mm/tlbflush.c @@ -103,22 +103,15 @@ static void __flush_tlb_range(struct cpumask *cmask, unsigned long asid, unsigned long start, unsigned long size, unsigned long stride) { - bool broadcast; + unsigned int cpu; if (cpumask_empty(cmask)) return; - if (cmask != cpu_online_mask) { - unsigned int cpuid; + cpu = get_cpu(); - cpuid = get_cpu(); - /* check if the tlbflush needs to be sent to other CPUs */ - broadcast = cpumask_any_but(cmask, cpuid) < nr_cpu_ids; - } else { - broadcast = true; - } - - if (!broadcast) { + /* Check if the TLB flush needs to be sent to other CPUs. */ + if (cpumask_any_but(cmask, cpu) >= nr_cpu_ids) { local_flush_tlb_range_asid(start, size, stride, asid); } else if (riscv_use_sbi_for_rfence()) { sbi_remote_sfence_vma_asid(cmask, start, size, asid); @@ -132,8 +125,7 @@ static void __flush_tlb_range(struct cpumask *cmask, unsigned long asid, on_each_cpu_mask(cmask, __ipi_flush_tlb_range_asid, &ftd, 1); } - if (cmask != cpu_online_mask) - put_cpu(); + put_cpu(); } static inline unsigned long get_mm_asid(struct mm_struct *mm) -- 2.30.2