linux-kernel - Re: [PATCH v2 04/13] arm64: mm: Push __TLBI_VADDR() into __tlbi

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Message-ID: <63283f63-f62f-4e8b-9611-94e6a64c49b7@arm.com>
Date: Tue, 27 Jan 2026 13:26:20 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: Jonathan Cameron <jonathan.cameron@...wei.com>
Cc: Will Deacon <will@...nel.org>, Ard Biesheuvel <ardb@...nel.org>,
 Catalin Marinas <catalin.marinas@....com>,
 Mark Rutland <mark.rutland@....com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Oliver Upton <oliver.upton@...ux.dev>, Marc Zyngier <maz@...nel.org>,
 Dev Jain <dev.jain@....com>, Linu Cherian <Linu.Cherian@....com>,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 04/13] arm64: mm: Push __TLBI_VADDR() into
 __tlbi_level()

On 27/01/2026 11:37, Jonathan Cameron wrote:
> On Mon, 19 Jan 2026 17:21:51 +0000
> Ryan Roberts <ryan.roberts@....com> wrote:
> 
>> From: Will Deacon <will@...nel.org>
>>
>> The __TLBI_VADDR() macro takes an ASID and an address and converts them
>> into a single argument formatted correctly for a TLB invalidation
>> instruction.
>>
>> Rather than have callers worry about this (especially in the case where
>> the ASID is zero), push the macro down into __tlbi_level() via a new
>> __tlbi_level_asid() helper.
>>
>> Signed-off-by: Will Deacon <will@...nel.org>
>> Reviewed-by: Linu Cherian <linu.cherian@....com>
>> Signed-off-by: Ryan Roberts <ryan.roberts@....com>
> One comment inline, but not particularly important given it's
> about reducing readability of a workaround a little
> 
> Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>
> 
>> @@ -674,6 +679,7 @@ static inline bool huge_pmd_needs_flush(pmd_t oldpmd, pmd_t newpmd)
>>  #define huge_pmd_needs_flush huge_pmd_needs_flush
>>  
>>  #undef __tlbi_user
>> +#undef __TLBI_VADDR
>>  #endif
>>  
>>  #endif
>> diff --git a/arch/arm64/kernel/sys_compat.c b/arch/arm64/kernel/sys_compat.c
>> index 4a609e9b65de..ad4857df4830 100644
>> --- a/arch/arm64/kernel/sys_compat.c
>> +++ b/arch/arm64/kernel/sys_compat.c
>> @@ -36,7 +36,7 @@ __do_compat_cache_op(unsigned long start, unsigned long end)
>>  			 * The workaround requires an inner-shareable tlbi.
>>  			 * We pick the reserved-ASID to minimise the impact.
>>  			 */
>> -			__tlbi(aside1is, __TLBI_VADDR(0, 0));
>> +			__tlbi(aside1is, 0UL);
> 
> Dropping the explicit ASID sort of looses some meaning here vs the comment just
> above it.  Meh, it's in a work around so most folk will ignore it anyway
> if reading this code, so I don't mind that much.

Agreed; personally I think the comment makes it clear what that zero is.

Thanks for all your reviews so far!

> 
>>  			dsb(ish);
>>  		}
>>  
>