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

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Message-ID: <mhng-41e9d23d-0d17-4b38-ba7c-1f8369f157d7@palmer-ri-x1c9>
Date:   Tue, 21 Mar 2023 22:45:17 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     dylan@...estech.com
CC:     zongbox@...il.com, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, guoren@...nel.org,
        sergey.matyukevich@...tacore.com, aou@...s.berkeley.edu,
        Paul Walmsley <paul.walmsley@...ive.com>, x5710999x@...il.com,
        tim609@...estech.com, peterlin@...estech.com,
        ycliang@...estech.com, Alistair Francis <Alistair.Francis@....com>
Subject:     Re: [PATCH v2] riscv: mm: Fix incorrect ASID argument when flushing TLB

On Mon, 20 Mar 2023 19:42:37 PDT (-0700), dylan@...estech.com wrote:
> 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?

Sorry about that, I guess I left it kind of vague as to who was doing 
what.  It looks like we've ended up with enough includes that v3 
actually builds now, it's queued up and should end up in fixes tomorrow 
morning.

Thanks!

>>
>> 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
>> > >