RISC-V: Issue a local tlbflush if possible. (31738ede) · Commits · 戴 / test

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 <atish.patra@wdc.com> Reviewed-by:

Christoph Hellwig <hch@lst.de> Signed-off-by:

Paul Walmsley <paul.walmsley@sifive.com>

arch/riscv/mm/tlbflush.c

+17 −2

Original line number	Diff line number	Diff line
		@@ -2,6 +2,7 @@

		#include <linux/mm.h>
		#include <linux/smp.h>
		#include <linux/sched.h>
		#include <asm/sbi.h>

		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;

		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(hmask.bits, start, size);
		sbi_remote_sfence_vma(cpumask_bits(&hmask), start, size);
		}

		put_cpu();
		}

		void flush_tlb_mm(struct mm_struct *mm)

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