Re: [PATCH -fixes] riscv: Fix arch_tlbbatch_flush() by clearing the batch cpumask

From: Samuel Holland <samuel.holland@sifive.com>
To: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Jisheng Zhang <jszhang@kernel.org>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -fixes] riscv: Fix arch_tlbbatch_flush() by clearing the batch cpumask
Date: Wed, 7 Feb 2024 13:23:55 -0600	[thread overview]
Message-ID: <a21e4253-9ef6-4c44-917c-02742440d192@sifive.com> (raw)
In-Reply-To: <20240130115508.105386-1-alexghiti@rivosinc.com>

Hi Alex,

On 2024-01-30 5:55 AM, Alexandre Ghiti wrote:
> We must clear the cpumask once we have flushed the batch, otherwise cpus
> get accumulated and we end sending IPIs to more cpus than needed.
> 
> Fixes: 54d7431af73e ("riscv: Add support for BATCHED_UNMAP_TLB_FLUSH")
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> ---
>  arch/riscv/mm/tlbflush.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
> index 99c3e037f127..c8efc3f87a0f 100644
> --- a/arch/riscv/mm/tlbflush.c
> +++ b/arch/riscv/mm/tlbflush.c
> @@ -240,4 +240,5 @@ void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
>  {
>  	__flush_tlb_range(NULL, &batch->cpumask,
>  			  0, FLUSH_TLB_MAX_SIZE, PAGE_SIZE);
> +	cpumask_clear(&batch->cpumask);
>  }

This patch doesn't apply to fixes -- it looks like it was based on "riscv: Call
secondary mmu notifier when flushing the tlb"[1], which has not been merged and
would go in for-next anyway. Otherwise:

Reviewed-by: Samuel Holland <samuel.holland@sifive.com>

[1]: https://lore.kernel.org/all/20240124080325.2324462-1-alexghiti@rivosinc.com/