linux-kernel - Re: [RFC PATCH v4 3/6] arm64: Add level-hinted TLB invalidation helper to tlbi

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Date:   Tue, 24 Mar 2020 14:19:39 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Zhenyu Ye <yezhenyu2@...wei.com>
Cc:     <will@...nel.org>, <mark.rutland@....com>,
        <catalin.marinas@....com>, <aneesh.kumar@...ux.ibm.com>,
        <akpm@...ux-foundation.org>, <npiggin@...il.com>,
        <peterz@...radead.org>, <arnd@...db.de>, <rostedt@...dmis.org>,
        <suzuki.poulose@....com>, <tglx@...utronix.de>,
        <yuzhao@...gle.com>, <Dave.Martin@....com>, <steven.price@....com>,
        <broonie@...nel.org>, <guohanjun@...wei.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-arch@...r.kernel.org>,
        <linux-mm@...ck.org>, <arm@...nel.org>, <xiexiangyou@...wei.com>,
        <prime.zeng@...ilicon.com>, <zhangshaokun@...ilicon.com>
Subject: Re: [RFC PATCH v4 3/6] arm64: Add level-hinted TLB invalidation
 helper to tlbi_user

On Tue, 24 Mar 2020 21:45:31 +0800
Zhenyu Ye <yezhenyu2@...wei.com> wrote:

> Add a level-hinted parameter to __tlbi_user, which only gets used
> if ARMv8.4-TTL gets detected.
> 
> ARMv8.4-TTL provides the TTL field in tlbi instruction to indicate
> the level of translation table walk holding the leaf entry for the
> address that is being invalidated.
> 
> This patch set the default level value to 0.
> 
> Signed-off-by: Zhenyu Ye <yezhenyu2@...wei.com>
> ---
>  arch/arm64/include/asm/tlbflush.h | 42 ++++++++++++++++++++++++++-----
>  1 file changed, 36 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index a3f70778a325..d141c080e494 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -89,6 +89,36 @@
>  		__tlbi(op,  arg);					\
>  	} while(0)
>  
> +#define __tlbi_user_level(op, addr, level)				\
> +	do {								\
> +		u64 arg = addr;						\
> +									\
> +		if (!arm64_kernel_unmapped_at_el0())			\
> +			break;						\
> +									\
> +		if (cpus_have_const_cap(ARM64_HAS_ARMv8_4_TTL) &&	\
> +		    level) {						\
> +			u64 ttl = level;				\
> +									\
> +			switch (PAGE_SIZE) {				\
> +			case SZ_4K:					\
> +				ttl |= 1 << 2;				\
> +				break;					\
> +			case SZ_16K:					\
> +				ttl |= 2 << 2;				\
> +				break;					\
> +			case SZ_64K:					\
> +				ttl |= 3 << 2;				\
> +				break;					\
> +			}						\
> +									\
> +			arg &= ~TLBI_TTL_MASK;				\
> +			arg |= FIELD_PREP(TLBI_TTL_MASK, ttl);		\
> +		}							\
> +									\
> +		__tlbi(op,  (arg) | USER_ASID_FLAG);
> 	\
> +	} while (0)
> +

Isn't this just:

define __tlbi_user_level(op, addr, level)			\
	do {							\
		if (!arm64_kernel_unmapped_at_el0())		\
			break;					\
								\
		__tlbi_level(op, addr | USER_ASID_FLAG, level);	\
	} while (0)

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...