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

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Date:   Tue, 14 Mar 2023 15:27:28 +0800
From:   Dylan Jhong <dylan@...estech.com>
To:     Zong Li <zongbox@...il.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>, <alistair.francis@....com>
Subject: Re: [PATCH v2] riscv: mm: Fix incorrect ASID argument when flushing
 TLB

On Tue, Mar 14, 2023 at 10:22:43AM +0800, Zong Li wrote:
> Dylan Jhong <dylan@...estech.com> 於 2023年3月13日 週一 下午12:29寫道：
> >
> > 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>
> > ---
> 
> Hi Dylan,
> Thanks for your patch, if I remember correctly, there was a patch from
> Alistair Francis did the similar fix. Perhaps we should track that
> patch to see why it doesn't be merged. Thanks.
> 
> http://lists.infradead.org/pipermail/linux-riscv/2022-March/013558.html
>
Hi Zong,
Thanks for the reminder, I didn't notice that Alistair had sent the same patch before.

Hi Palmer, Alistair
http://lists.infradead.org/pipermail/linux-riscv/2022-March/013597.html
This patch does not seem to be cherry-picked back to the released linux kernel,
and I have not seen the v4 patch. May I ask how is the follow-up progress of this patch?

Best,
Dylan

> > 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
> > --
> > 2.34.1
> >