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.poul...@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)
+
+/*
+ * CPU errata detected at boot time based on feature of one or more CPUs.
+ * It is not safe for a late CPU to have this feature when the system doesn't
+ * have it. But it is safe to miss the feature if the system has it.
+ */
+#define ARM64_CPUCAP_STRICT_CPU_LOCAL_ERRATUM \
+ (ARM64_CPUCAP_SCOPE_LOCAL_CPU | ARM64_CPUCAP_LATE_CPU_SAFE_TO_MISS)
+/*
+ * CPU feature detected at boot time based on system-wide value of a feature.
+ * It is safe for a late CPU to have this feature even though the system
doesn't
+ * have it already. But the CPU must have this feature if the system does.
+ */
+#define ARM64_CPUCAP_BOOT_SYSTEM_FEATURE \
+ (ARM64_CPUCAP_SCOPE_SYSTEM | ARM64_CPUCAP_LATE_CPU_SAFE_TO_HAVE)
struct arm64_cpu_capabilities {
const char *desc;
@@ -128,6 +143,18 @@ static inline int cpucap_default_scope(const struct
arm64_cpu_capabilities *cap)
return cap->type & ARM64_CPUCAP_SCOPE_MASK;
}
+static inline bool
+cpucap_late_cpu_missing_cap_safe(const struct arm64_cpu_capabilities *cap)
+{
+ return !!(cap->type & ARM64_CPUCAP_LATE_CPU_SAFE_TO_MISS);
+}
+
+static inline bool
+cpucap_late_cpu_have_cap_safe(const struct arm64_cpu_capabilities *cap)
+{
+ return !!(cap->type & ARM64_CPUCAP_LATE_CPU_SAFE_TO_HAVE);
+}
+
extern DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS);
extern struct static_key_false cpu_hwcap_keys[ARM64_NCAPS];
extern struct static_key_false arm64_const_caps_ready;
--
2.13.6
