From 31738ede9b339c90216b8fd10da0b1567a041f06 Mon Sep 17 00:00:00 2001 From: Atish Patra Date: Thu, 22 Aug 2019 00:51:50 -0700 Subject: [PATCH] RISC-V: Issue a local tlbflush if possible. In RISC-V, tlb flush happens via SBI which is expensive. If the local cpu is the only cpu in cpumask, there is no need to invoke a SBI call. Just do a local flush and return. Signed-off-by: Atish Patra Reviewed-by: Christoph Hellwig Signed-off-by: Paul Walmsley --- arch/riscv/mm/tlbflush.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c index 9ecaf73..3531d46 100644 --- a/arch/riscv/mm/tlbflush.c +++ b/arch/riscv/mm/tlbflush.c @@ -2,6 +2,7 @@ #include #include +#include #include void flush_tlb_all(void) @@ -9,16 +10,30 @@ void flush_tlb_all(void) sbi_remote_sfence_vma(NULL, 0, -1); } +/* + * This function must not be called with cmask being null. + * Kernel may panic if cmask is NULL. + */ static void __sbi_tlb_flush_range(struct cpumask *cmask, unsigned long start, unsigned long size) { struct cpumask hmask; + unsigned int cpuid; if (cpumask_empty(cmask)) return; - riscv_cpuid_to_hartid_mask(cmask, &hmask); - sbi_remote_sfence_vma(hmask.bits, start, size); + cpuid = get_cpu(); + + if (cpumask_any_but(cmask, cpuid) >= nr_cpu_ids) { + /* local cpu is the only cpu present in cpumask */ + local_flush_tlb_all(); + } else { + riscv_cpuid_to_hartid_mask(cmask, &hmask); + sbi_remote_sfence_vma(cpumask_bits(&hmask), start, size); + } + + put_cpu(); } void flush_tlb_mm(struct mm_struct *mm) -- 2.7.4