Re: [PATCH v4 05/10] powerpc/dt_cpu_ftrs: Add feature for 2nd DAWR
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2020-07-21 11:29:29
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Ravi Bangoria [off-list ref] writes:
On 7/17/20 11:14 AM, Jordan Niethe wrote:quoted
On Fri, Jul 17, 2020 at 2:10 PM Ravi Bangoria [off-list ref] wrote:quoted
Add new device-tree feature for 2nd DAWR. If this feature is present, 2nd DAWR is supported, otherwise not. Signed-off-by: Ravi Bangoria <redacted> --- 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)
quoted
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