linux-kernel - Re: [PATCH v2 1/7] powerpc: Add TIDR CPU feature for Power9

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Date:   Mon, 7 May 2018 19:17:25 +0200
From:   Frederic Barrat <fbarrat@...ux.ibm.com>
To:     "Alastair D'Silva" <alastair@....ibm.com>,
        linuxppc-dev@...ts.ozlabs.org
Cc:     linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        mikey@...ling.org, vaibhav@...ux.vnet.ibm.com,
        aneesh.kumar@...ux.vnet.ibm.com, malat@...ian.org,
        felix@...ux.vnet.ibm.com, pombredanne@...b.com,
        sukadev@...ux.vnet.ibm.com, npiggin@...il.com,
        gregkh@...uxfoundation.org, arnd@...db.de,
        andrew.donnellan@....ibm.com, fbarrat@...ux.vnet.ibm.com,
        corbet@....net, "Alastair D'Silva" <alastair@...ilva.org>
Subject: Re: [PATCH v2 1/7] powerpc: Add TIDR CPU feature for Power9



Le 18/04/2018 à 03:08, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@...ilva.org>
> 
> This patch adds a CPU feature bit to show whether the CPU has
> the TIDR register available, enabling as_notify/wait in userspace.
> 
> Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
> ---
>   arch/powerpc/include/asm/cputable.h | 3 ++-
>   arch/powerpc/kernel/dt_cpu_ftrs.c   | 1 +
>   2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
> index 4e332f3531c5..54c4cbbe57b4 100644
> --- a/arch/powerpc/include/asm/cputable.h
> +++ b/arch/powerpc/include/asm/cputable.h
> @@ -215,6 +215,7 @@ static inline void cpu_feature_keys_init(void) { }
>   #define CPU_FTR_P9_TM_HV_ASSIST		LONG_ASM_CONST(0x0000100000000000)
>   #define CPU_FTR_P9_TM_XER_SO_BUG	LONG_ASM_CONST(0x0000200000000000)
>   #define CPU_FTR_P9_TLBIE_BUG		LONG_ASM_CONST(0x0000400000000000)
> +#define CPU_FTR_P9_TIDR			LONG_ASM_CONST(0x0000800000000000)
> 
>   #ifndef __ASSEMBLY__
> 
> @@ -462,7 +463,7 @@ static inline void cpu_feature_keys_init(void) { }
>   	    CPU_FTR_CFAR | CPU_FTR_HVMODE | CPU_FTR_VMX_COPY | \
>   	    CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
>   	    CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
> -	    CPU_FTR_P9_TLBIE_BUG)
> +	    CPU_FTR_P9_TLBIE_BUG | CPU_FTR_P9_TIDR)
>   #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
>   			     (~CPU_FTR_SAO))
>   #define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
> diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
> index 11a3a4fed3fb..10f8b7f55637 100644
> --- a/arch/powerpc/kernel/dt_cpu_ftrs.c
> +++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
> @@ -722,6 +722,7 @@ static __init void cpufeatures_cpu_quirks(void)
>   	if ((version & 0xffff0000) == 0x004e0000) {
>   		cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);
>   		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TLBIE_BUG; > +		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TIDR;


Isn't it redundant with adding the flag to CPU_FTRS_POWER9?

   Fred


>   	}
>   }
>