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Date: Thu, 4 Apr 2024 13:15:06 -0500
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Subject: Re: [PATCH v2 1/2] riscv: thead: Rename T-Head PBMT to MAEE
To: =?UTF-8?Q?Christoph_M=C3=BCllner?= <christoph.muellner@vrull.eu>,
 linux-riscv@lists.infradead.org
References: <20240329121414.688391-1-christoph.muellner@vrull.eu>
 <20240329121414.688391-2-christoph.muellner@vrull.eu>
From: Samuel Holland <samuel.holland@sifive.com>
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Cc: linux-kernel@vger.kernel.org, Palmer Dabbelt <palmer@dabbelt.com>,
 Paul Walmsley <paul.walmsley@sifive.com>, Albert Ou <aou@eecs.berkeley.edu>,
 Philipp Tomsich <philipp.tomsich@vrull.eu>, =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?=
 <bjorn@kernel.org>, Daniel Henrique Barboza <dbarboza@ventanamicro.com>,
 Heiko Stuebner <heiko@sntech.de>, Cooper Qu <cooper.qu@linux.alibaba.com>,
 Zhiwei Liu <zhiwei_liu@linux.alibaba.com>,
 Huang Tao <eric.huang@linux.alibaba.com>,
 Alistair Francis <alistair.francis@wdc.com>,
 Andrew Jones <ajones@ventanamicro.com>, Conor Dooley <conor@kernel.org>,
 Qingfang Deng <dqfext@gmail.com>, Alexandre Ghiti <alex@ghiti.fr>
In-Reply-To: <20240329121414.688391-2-christoph.muellner@vrull.eu>
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Hi Christoph,

On 2024-03-29 7:14 AM, Christoph Müllner wrote:
> T-Head's vendor extension to set page attributes has the name
> MAEE (MMU address attribute extension).
> Let's rename it, so it is clear what this referes to.
> 
> See also:
>   https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadmaee.adoc

My understanding is that MAEE is the name of the CSR bit and stands for "MMU (or
Memory) Attribute Extension Enable", so the name for the extension itself would
be "MAE" (just one E). This is similar to THEADISAEE => T-HEAD ISA Extension
Enable. Does that sound right?

Regards,
Samuel

> Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
> ---
>  arch/riscv/Kconfig.errata            |  8 ++++----
>  arch/riscv/errata/thead/errata.c     |  8 ++++----
>  arch/riscv/include/asm/errata_list.h | 20 ++++++++++----------
>  3 files changed, 18 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/riscv/Kconfig.errata b/arch/riscv/Kconfig.errata
> index 910ba8837add..2c24bef7e112 100644
> --- a/arch/riscv/Kconfig.errata
> +++ b/arch/riscv/Kconfig.errata
> @@ -82,14 +82,14 @@ config ERRATA_THEAD
>  
>  	  Otherwise, please say "N" here to avoid unnecessary overhead.
>  
> -config ERRATA_THEAD_PBMT
> -	bool "Apply T-Head memory type errata"
> +config ERRATA_THEAD_MAEE
> +	bool "Apply T-Head's MMU address attribute (MAEE)"
>  	depends on ERRATA_THEAD && 64BIT && MMU
>  	select RISCV_ALTERNATIVE_EARLY
>  	default y
>  	help
> -	  This will apply the memory type errata to handle the non-standard
> -	  memory type bits in page-table-entries on T-Head SoCs.
> +	  This will apply the memory type errata to handle T-Head's MMU address
> +	  attribute extension (MAEE).
>  
>  	  If you don't know what to do here, say "Y".
>  
> diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
> index b1c410bbc1ae..8c8a8a4b0421 100644
> --- a/arch/riscv/errata/thead/errata.c
> +++ b/arch/riscv/errata/thead/errata.c
> @@ -19,10 +19,10 @@
>  #include <asm/patch.h>
>  #include <asm/vendorid_list.h>
>  
> -static bool errata_probe_pbmt(unsigned int stage,
> +static bool errata_probe_maee(unsigned int stage,
>  			      unsigned long arch_id, unsigned long impid)
>  {
> -	if (!IS_ENABLED(CONFIG_ERRATA_THEAD_PBMT))
> +	if (!IS_ENABLED(CONFIG_ERRATA_THEAD_MAEE))
>  		return false;
>  
>  	if (arch_id != 0 || impid != 0)
> @@ -140,8 +140,8 @@ static u32 thead_errata_probe(unsigned int stage,
>  {
>  	u32 cpu_req_errata = 0;
>  
> -	if (errata_probe_pbmt(stage, archid, impid))
> -		cpu_req_errata |= BIT(ERRATA_THEAD_PBMT);
> +	if (errata_probe_maee(stage, archid, impid))
> +		cpu_req_errata |= BIT(ERRATA_THEAD_MAEE);
>  
>  	errata_probe_cmo(stage, archid, impid);
>  
> diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
> index ea33288f8a25..7c377e137b41 100644
> --- a/arch/riscv/include/asm/errata_list.h
> +++ b/arch/riscv/include/asm/errata_list.h
> @@ -23,7 +23,7 @@
>  #endif
>  
>  #ifdef CONFIG_ERRATA_THEAD
> -#define	ERRATA_THEAD_PBMT 0
> +#define	ERRATA_THEAD_MAEE 0
>  #define	ERRATA_THEAD_PMU 1
>  #define	ERRATA_THEAD_NUMBER 2
>  #endif
> @@ -53,20 +53,20 @@ asm(ALTERNATIVE("sfence.vma %0", "sfence.vma", SIFIVE_VENDOR_ID,	\
>   * in the default case.
>   */
>  #define ALT_SVPBMT_SHIFT 61
> -#define ALT_THEAD_PBMT_SHIFT 59
> +#define ALT_THEAD_MAEE_SHIFT 59
>  #define ALT_SVPBMT(_val, prot)						\
>  asm(ALTERNATIVE_2("li %0, 0\t\nnop",					\
>  		  "li %0, %1\t\nslli %0,%0,%3", 0,			\
>  			RISCV_ISA_EXT_SVPBMT, CONFIG_RISCV_ISA_SVPBMT,	\
>  		  "li %0, %2\t\nslli %0,%0,%4", THEAD_VENDOR_ID,	\
> -			ERRATA_THEAD_PBMT, CONFIG_ERRATA_THEAD_PBMT)	\
> +			ERRATA_THEAD_MAEE, CONFIG_ERRATA_THEAD_MAEE)	\
>  		: "=r"(_val)						\
>  		: "I"(prot##_SVPBMT >> ALT_SVPBMT_SHIFT),		\
> -		  "I"(prot##_THEAD >> ALT_THEAD_PBMT_SHIFT),		\
> +		  "I"(prot##_THEAD >> ALT_THEAD_MAEE_SHIFT),		\
>  		  "I"(ALT_SVPBMT_SHIFT),				\
> -		  "I"(ALT_THEAD_PBMT_SHIFT))
> +		  "I"(ALT_THEAD_MAEE_SHIFT))
>  
> -#ifdef CONFIG_ERRATA_THEAD_PBMT
> +#ifdef CONFIG_ERRATA_THEAD_MAEE
>  /*
>   * IO/NOCACHE memory types are handled together with svpbmt,
>   * so on T-Head chips, check if no other memory type is set,
> @@ -83,11 +83,11 @@ asm volatile(ALTERNATIVE(						\
>  	"slli    t3, t3, %3\n\t"					\
>  	"or      %0, %0, t3\n\t"					\
>  	"2:",  THEAD_VENDOR_ID,						\
> -		ERRATA_THEAD_PBMT, CONFIG_ERRATA_THEAD_PBMT)		\
> +		ERRATA_THEAD_MAEE, CONFIG_ERRATA_THEAD_MAEE)		\
>  	: "+r"(_val)							\
> -	: "I"(_PAGE_MTMASK_THEAD >> ALT_THEAD_PBMT_SHIFT),		\
> -	  "I"(_PAGE_PMA_THEAD >> ALT_THEAD_PBMT_SHIFT),			\
> -	  "I"(ALT_THEAD_PBMT_SHIFT)					\
> +	: "I"(_PAGE_MTMASK_THEAD >> ALT_THEAD_MAEE_SHIFT),		\
> +	  "I"(_PAGE_PMA_THEAD >> ALT_THEAD_MAEE_SHIFT),			\
> +	  "I"(ALT_THEAD_MAEE_SHIFT)					\
>  	: "t3")
>  #else
>  #define ALT_THEAD_PMA(_val)