Re: [RFC PATCH 1/2] powerpc: Add a CPU feature bit for TM bug workarounds on POWER9 DD2.2

[David Gibson <david@gibson.dropbear.id.au>]

[-- Attachment #1: Type: text/plain, Size: 3473 bytes --]

On Fri, Dec 08, 2017 at 05:09:24PM +1100, Paul Mackerras wrote:
> This adds a CPU feature bit which is set for POWER9 DD2.2 processors
> which will be used to enable software emulation for some transactional
> memory instructions, in order to work around hardware bugs.
> 
> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  arch/powerpc/include/asm/cputable.h |  5 ++++-
>  arch/powerpc/kernel/cputable.c      | 20 ++++++++++++++++++++
>  2 files changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
> index 53b31c2bcdf4..70cee46c046c 100644
> --- a/arch/powerpc/include/asm/cputable.h
> +++ b/arch/powerpc/include/asm/cputable.h
> @@ -215,6 +215,7 @@ enum {
>  #define CPU_FTR_DAWR			LONG_ASM_CONST(0x0400000000000000)
>  #define CPU_FTR_DABRX			LONG_ASM_CONST(0x0800000000000000)
>  #define CPU_FTR_PMAO_BUG		LONG_ASM_CONST(0x1000000000000000)
> +#define CPU_FTR_P9_TM_EMUL		LONG_ASM_CONST(0x2000000000000000)
>  #define CPU_FTR_POWER9_DD1		LONG_ASM_CONST(0x4000000000000000)
>  
>  #ifndef __ASSEMBLY__
> @@ -478,6 +479,7 @@ enum {
>  	    CPU_FTR_ARCH_207S | CPU_FTR_TM_COMP | CPU_FTR_ARCH_300)
>  #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
>  			     (~CPU_FTR_SAO))
> +#define CPU_FTRS_POWER9_DD2_2 (CPU_FTRS_POWER9 | CPU_FTR_P9_TM_EMUL)
>  #define CPU_FTRS_CELL	(CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \
>  	    CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \
>  	    CPU_FTR_ALTIVEC_COMP | CPU_FTR_MMCRA | CPU_FTR_SMT | \
> @@ -496,7 +498,8 @@ enum {
>  	    (CPU_FTRS_POWER4 | CPU_FTRS_PPC970 | CPU_FTRS_POWER5 | \
>  	     CPU_FTRS_POWER6 | CPU_FTRS_POWER7 | CPU_FTRS_POWER8E | \
>  	     CPU_FTRS_POWER8 | CPU_FTRS_POWER8_DD1 | CPU_FTRS_CELL | \
> -	     CPU_FTRS_PA6T | CPU_FTR_VSX | CPU_FTRS_POWER9 | CPU_FTRS_POWER9_DD1)
> +	     CPU_FTRS_PA6T | CPU_FTR_VSX | CPU_FTRS_POWER9 | \
> +	     CPU_FTRS_POWER9_DD1 | CPU_FTRS_POWER9_DD2_2)
>  #endif
>  #else
>  enum {
> diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
> index 760872916013..bb94bb6d9e4d 100644
> --- a/arch/powerpc/kernel/cputable.c
> +++ b/arch/powerpc/kernel/cputable.c
> @@ -547,6 +547,26 @@ static struct cpu_spec __initdata cpu_specs[] = {
>  		.machine_check_early	= __machine_check_early_realmode_p9,
>  		.platform		= "power9",
>  	},
> +	{	/* Power9 DD2.2 */
> +		.pvr_mask		= 0xffffffff,
> +		.pvr_value		= 0x004e1202,
> +		.cpu_name		= "POWER9 (raw)",
> +		.cpu_features		= CPU_FTRS_POWER9_DD2_2,
> +		.cpu_user_features	= COMMON_USER_POWER9,
> +		.cpu_user_features2	= COMMON_USER2_POWER9,
> +		.mmu_features		= MMU_FTRS_POWER9,
> +		.icache_bsize		= 128,
> +		.dcache_bsize		= 128,
> +		.num_pmcs		= 6,
> +		.pmc_type		= PPC_PMC_IBM,
> +		.oprofile_cpu_type	= "ppc64/power9",
> +		.oprofile_type		= PPC_OPROFILE_INVALID,
> +		.cpu_setup		= __setup_cpu_power9,
> +		.cpu_restore		= __restore_cpu_power9,
> +		.flush_tlb		= __flush_tlb_power9,
> +		.machine_check_early	= __machine_check_early_realmode_p9,
> +		.platform		= "power9",
> +	},
>  	{	/* Power9 */
>  		.pvr_mask		= 0xffff0000,
>  		.pvr_value		= 0x004e0000,

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]