[PATCH 05/16] arm64: Add flags to check the safety of a capability for late CPU
From: Dave.Martin@arm.com (Dave Martin)
Date: 2018-01-26 10:10:27
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On Tue, Jan 23, 2018 at 12:27:58PM +0000, Suzuki K Poulose wrote:
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Add two different flags to indicate if the conflict of a capability on a late CPU with the current system state 1) Can a CPU have a capability when the system doesn't have it ? Most arm64 features could have this set. While erratum work arounds cannot have this, as we may miss work arounds. 2) Can a CPU miss a capability when the system has it ? This could be set for arm64 erratum work arounds as we don't care if a CPU doesn't need the work around. However it should be clear for features. These flags could be added to certain entries based on their nature. Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> --- arch/arm64/include/asm/cpufeature.h | 35 +++++++++++++++++++++++++++++++---- 1 file changed, 31 insertions(+), 4 deletions(-)diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 4fd5de8ef33e..27d037bb0451 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h@@ -94,10 +94,25 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0; #define SCOPE_SYSTEM ARM64_CPUCAP_SCOPE_SYSTEM #define SCOPE_LOCAL_CPU ARM64_CPUCAP_SCOPE_LOCAL_CPU -/* CPU errata detected at boot time based on feature of one or more CPUs */ -#define ARM64_CPUCAP_STRICT_CPU_LOCAL_ERRATUM (ARM64_CPUCAP_SCOPE_LOCAL_CPU) -/* CPU feature detected at boot time based on system-wide value of a feature */ -#define ARM64_CPUCAP_BOOT_SYSTEM_FEATURE (ARM64_CPUCAP_SCOPE_SYSTEM) +/* Is it safe for a late CPU to have this capability when system doesn't already have */ +#define ARM64_CPUCAP_LATE_CPU_SAFE_TO_HAVE BIT(2) +/* Is it safe for a late CPU to miss this capability when system has it */ +#define ARM64_CPUCAP_LATE_CPU_SAFE_TO_MISS BIT(3)
Maybe _OPTIONAL and _PERMITTED would be a bit less verbose? Alternatively, ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU might be easier to understand. [...] Cheers ---Dave