Ravi Bangoria <ravi.bango...@linux.ibm.com> writes: > On 7/17/20 11:14 AM, Jordan Niethe wrote: >> On Fri, Jul 17, 2020 at 2:10 PM Ravi Bangoria >> <ravi.bango...@linux.ibm.com> wrote: >>> >>> Add new device-tree feature for 2nd DAWR. If this feature is present, >>> 2nd DAWR is supported, otherwise not. >>> >>> Signed-off-by: Ravi Bangoria <ravi.bango...@linux.ibm.com> >>> --- >>> arch/powerpc/include/asm/cputable.h | 7 +++++-- >>> arch/powerpc/kernel/dt_cpu_ftrs.c | 7 +++++++ >>> 2 files changed, 12 insertions(+), 2 deletions(-) >>> >>> diff --git a/arch/powerpc/include/asm/cputable.h >>> b/arch/powerpc/include/asm/cputable.h >>> index e506d429b1af..3445c86e1f6f 100644 >>> --- a/arch/powerpc/include/asm/cputable.h >>> +++ b/arch/powerpc/include/asm/cputable.h >>> @@ -214,6 +214,7 @@ static inline void cpu_feature_keys_init(void) { } >>> #define CPU_FTR_P9_TLBIE_ERAT_BUG LONG_ASM_CONST(0x0001000000000000) >>> #define CPU_FTR_P9_RADIX_PREFETCH_BUG LONG_ASM_CONST(0x0002000000000000) >>> #define CPU_FTR_ARCH_31 >>> LONG_ASM_CONST(0x0004000000000000) >>> +#define CPU_FTR_DAWR1 LONG_ASM_CONST(0x0008000000000000) >>> >>> #ifndef __ASSEMBLY__ >>> >>> @@ -497,14 +498,16 @@ static inline void cpu_feature_keys_init(void) { } >>> #define CPU_FTRS_POSSIBLE \ >>> (CPU_FTRS_POWER7 | CPU_FTRS_POWER8E | CPU_FTRS_POWER8 | \ >>> CPU_FTR_ALTIVEC_COMP | CPU_FTR_VSX_COMP | CPU_FTRS_POWER9 | \ >>> - CPU_FTRS_POWER9_DD2_1 | CPU_FTRS_POWER9_DD2_2 | >>> CPU_FTRS_POWER10) >>> + CPU_FTRS_POWER9_DD2_1 | CPU_FTRS_POWER9_DD2_2 | >>> CPU_FTRS_POWER10 | \ >>> + CPU_FTR_DAWR1) >>> #else >>> #define CPU_FTRS_POSSIBLE \ >>> (CPU_FTRS_PPC970 | CPU_FTRS_POWER5 | \ >>> CPU_FTRS_POWER6 | CPU_FTRS_POWER7 | CPU_FTRS_POWER8E | \ >>> CPU_FTRS_POWER8 | CPU_FTRS_CELL | CPU_FTRS_PA6T | \ >>> CPU_FTR_VSX_COMP | CPU_FTR_ALTIVEC_COMP | CPU_FTRS_POWER9 | \ >>> - CPU_FTRS_POWER9_DD2_1 | CPU_FTRS_POWER9_DD2_2 | >>> CPU_FTRS_POWER10) >>> + CPU_FTRS_POWER9_DD2_1 | CPU_FTRS_POWER9_DD2_2 | >>> CPU_FTRS_POWER10 | \ >>> + CPU_FTR_DAWR1)
>> Instead of putting CPU_FTR_DAWR1 into CPU_FTRS_POSSIBLE should it go >> into CPU_FTRS_POWER10? >> Then it will be picked up by CPU_FTRS_POSSIBLE. > > I remember a discussion about this with Mikey and we decided to do it > this way. Obviously, the purpose is to make CPU_FTR_DAWR1 independent of > CPU_FTRS_POWER10 because DAWR1 is an optional feature in p10. I fear > including CPU_FTR_DAWR1 in CPU_FTRS_POWER10 can make it forcefully enabled > even when device-tree property is not present or pa-feature bit it not set, > because we do: > > { /* 3.1-compliant processor, i.e. Power10 "architected" mode */ > .pvr_mask = 0xffffffff, > .pvr_value = 0x0f000006, > .cpu_name = "POWER10 (architected)", > .cpu_features = CPU_FTRS_POWER10, The pa-features logic will turn it off if the feature bit is not set. So you should be able to put it in CPU_FTRS_POWER10. See for example CPU_FTR_NOEXECUTE. cheers