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

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Date:   Thu, 23 Mar 2023 13:47:03 -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 Tue, 21 Mar 2023 22:45:17 PDT (-0700), Palmer Dabbelt wrote:
> 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.

Turns out that one still fails some configs, and the one posted here 
doesn't.   So I've got the new one on fixes.

Thanks!

>
> 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
>>> > >