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Re: [Qemu-devel] [PATCH 14/16] cputlb: remove tb_lock from tlb_flush fun
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH 14/16] cputlb: remove tb_lock from tlb_flush functions |
Date: |
Thu, 29 Mar 2018 16:46:31 +0100 |
User-agent: |
mu4e 1.1.0; emacs 26.0.91 |
Emilio G. Cota <address@hidden> writes:
> The acquisition of tb_lock was added when the async tlb_flush
> was introduced in e3b9ca810 ("cputlb: introduce tlb_flush_* async work.")
>
> tb_lock was there to allow us to do memset() on the tb_jmp_cache's.
> However, since f3ced3c5928 ("tcg: consistently access cpu->tb_jmp_cache
> atomically") all accesses to tb_jmp_cache are atomic, so tb_lock
> is not needed here. Get rid of it.
\o/
Reviewed-by: Alex Bennée <address@hidden>
>
> Signed-off-by: Emilio G. Cota <address@hidden>
> ---
> accel/tcg/cputlb.c | 8 --------
> 1 file changed, 8 deletions(-)
>
> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
> index 0543903..f5c3a09 100644
> --- a/accel/tcg/cputlb.c
> +++ b/accel/tcg/cputlb.c
> @@ -125,8 +125,6 @@ static void tlb_flush_nocheck(CPUState *cpu)
> atomic_set(&env->tlb_flush_count, env->tlb_flush_count + 1);
> tlb_debug("(count: %zu)\n", tlb_flush_count());
>
> - tb_lock();
> -
> memset(env->tlb_table, -1, sizeof(env->tlb_table));
> memset(env->tlb_v_table, -1, sizeof(env->tlb_v_table));
> cpu_tb_jmp_cache_clear(cpu);
> @@ -135,8 +133,6 @@ static void tlb_flush_nocheck(CPUState *cpu)
> env->tlb_flush_addr = -1;
> env->tlb_flush_mask = 0;
>
> - tb_unlock();
> -
> atomic_mb_set(&cpu->pending_tlb_flush, 0);
> }
>
> @@ -180,8 +176,6 @@ static void tlb_flush_by_mmuidx_async_work(CPUState *cpu,
> run_on_cpu_data data)
>
> assert_cpu_is_self(cpu);
>
> - tb_lock();
> -
> tlb_debug("start: mmu_idx:0x%04lx\n", mmu_idx_bitmask);
>
> for (mmu_idx = 0; mmu_idx < NB_MMU_MODES; mmu_idx++) {
> @@ -197,8 +191,6 @@ static void tlb_flush_by_mmuidx_async_work(CPUState *cpu,
> run_on_cpu_data data)
> cpu_tb_jmp_cache_clear(cpu);
>
> tlb_debug("done\n");
> -
> - tb_unlock();
> }
>
> void tlb_flush_by_mmuidx(CPUState *cpu, uint16_t idxmap)
--
Alex Bennée
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