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

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Date:   Tue, 21 Mar 2023 10:42:37 +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 03:27:30PM +0800, Dylan Jhong wrote:
> 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
>

Hi Palmer,

Ping. Any update on this?

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
> > >