linux-kernel - Re: [PATCH v2] riscv: mm: Fix incorrect ASID argument when flushing TLB

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Message-ID: <ZA67iqLoX9DUjGm/@curiosity>
Date:   Mon, 13 Mar 2023 08:58:34 +0300
From:   Sergey Matyukevich <geomatsi@...il.com>
To:     Dylan Jhong <dylan@...estech.com>
Cc:     linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        guoren@...nel.org, sergey.matyukevich@...tacore.com,
        aou@...s.berkeley.edu, palmer@...belt.com,
        paul.walmsley@...ive.com, x5710999x@...il.com,
        tim609@...estech.com, peterlin@...estech.com, ycliang@...estech.com
Subject: Re: [PATCH v2] riscv: mm: Fix incorrect ASID argument when flushing
 TLB

> Currently, we pass the CONTEXTID instead of the ASID to the TLB flush
> function. We should only take the ASID field to prevent from touching
> the reserved bit field.
> 
> Fixes: 3f1e782998cd ("riscv: add ASID-based tlbflushing methods")
> Signed-off-by: Dylan Jhong <dylan@...estech.com>
> ---
> Changes from v2:
> - Remove unsued EXPORT_SYMBOL()
> ---
>  arch/riscv/include/asm/tlbflush.h | 2 ++
>  arch/riscv/mm/context.c           | 2 +-
>  arch/riscv/mm/tlbflush.c          | 2 +-
>  3 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
> index 907b9efd39a8..597d6d8aec28 100644
> --- a/arch/riscv/include/asm/tlbflush.h
> +++ b/arch/riscv/include/asm/tlbflush.h
> @@ -12,6 +12,8 @@
>  #include <asm/errata_list.h>
>  
>  #ifdef CONFIG_MMU
> +extern unsigned long asid_mask;
> +
>  static inline void local_flush_tlb_all(void)
>  {
>  	__asm__ __volatile__ ("sfence.vma" : : : "memory");
> diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
> index 80ce9caba8d2..6d1aeb063e81 100644
> --- a/arch/riscv/mm/context.c
> +++ b/arch/riscv/mm/context.c
> @@ -22,7 +22,7 @@ DEFINE_STATIC_KEY_FALSE(use_asid_allocator);
>  
>  static unsigned long asid_bits;
>  static unsigned long num_asids;
> -static unsigned long asid_mask;
> +unsigned long asid_mask;
>  
>  static atomic_long_t current_version;
>  
> diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
> index ce7dfc81bb3f..ba4c27187c95 100644
> --- a/arch/riscv/mm/tlbflush.c
> +++ b/arch/riscv/mm/tlbflush.c
> @@ -27,7 +27,7 @@ static void __sbi_tlb_flush_range(struct mm_struct *mm, unsigned long start,
>  	/* check if the tlbflush needs to be sent to other CPUs */
>  	broadcast = cpumask_any_but(cmask, cpuid) < nr_cpu_ids;
>  	if (static_branch_unlikely(&use_asid_allocator)) {
> -		unsigned long asid = atomic_long_read(&mm->context.id);
> +		unsigned long asid = atomic_long_read(&mm->context.id) & asid_mask;
>  
>  		/*
>  		 * TLB will be immediately flushed on harts concurrently

Reviewed-by: Sergey Matyukevich <sergey.matyukevich@...tacore.com>

Thanks !