On Tue, Jan 02, 2024 at 02:00:49PM -0800, Samuel Holland wrote:
> Even if multiple ASIDs are not supported, using the single-ASID variant
> of the sfence.vma instruction preserves TLB entries for global (kernel)
> pages. So it is always more efficient to use the single-ASID code path.
>
> Signed-off-by: Samuel Holland <samuel.holland@xxxxxxxxxx>
> ---
>
> Changes in v4:
> - There is now only one copy of __flush_tlb_range()
>
> Changes in v2:
> - Update both copies of __flush_tlb_range()
>
> arch/riscv/include/asm/mmu_context.h | 2 --
> arch/riscv/mm/context.c | 3 +--
> arch/riscv/mm/tlbflush.c | 3 +--
> 3 files changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/arch/riscv/include/asm/mmu_context.h b/arch/riscv/include/asm/mmu_context.h
> index 7030837adc1a..b0659413a080 100644
> --- a/arch/riscv/include/asm/mmu_context.h
> +++ b/arch/riscv/include/asm/mmu_context.h
> @@ -33,8 +33,6 @@ static inline int init_new_context(struct task_struct *tsk,
> return 0;
> }
>
> -DECLARE_STATIC_KEY_FALSE(use_asid_allocator);
> -
> #include <asm-generic/mmu_context.h>
>
> #endif /* _ASM_RISCV_MMU_CONTEXT_H */
> diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
> index 3ca9b653df7d..20057085ab8a 100644
> --- a/arch/riscv/mm/context.c
> +++ b/arch/riscv/mm/context.c
> @@ -18,8 +18,7 @@
>
> #ifdef CONFIG_MMU
>
> -DEFINE_STATIC_KEY_FALSE(use_asid_allocator);
> -
> +static DEFINE_STATIC_KEY_FALSE(use_asid_allocator);
One of my optimization "riscv: tlb: avoid tlb flushing if fullmm == 1"
will make use of use_asid_allocator, so could we remove this modification?
> static unsigned long num_asids;
>
> static atomic_long_t current_version;
> diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
> index 5ec621545c69..39d80f56d292 100644
> --- a/arch/riscv/mm/tlbflush.c
> +++ b/arch/riscv/mm/tlbflush.c
> @@ -84,8 +84,7 @@ static void __flush_tlb_range(struct mm_struct *mm, unsigned long start,
> if (cpumask_empty(cmask))
> return;
>
> - if (static_branch_unlikely(&use_asid_allocator))
> - asid = cntx2asid(atomic_long_read(&mm->context.id));
> + asid = cntx2asid(atomic_long_read(&mm->context.id));
> } else {
> cmask = cpu_online_mask;
> }
> --
> 2.42.0
>
>
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