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arm64: cpufeature: Add ARM64_CPUCAP_SOC_ERRATUM for SoC-level errata

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Add a new capability type for SoC-level (not CPU-level) errata. Unlike
CPU errata which need to be checked on every CPU, SoC errata are probed
once on the boot CPU and the result applies to all CPUs. Secondary
and late CPUs skip the matches() check but still get cpu_enable() called.

This avoids redundant probing on secondary and late CPUs for errata
that are SoC-wide properties, not per-CPU.

Convert ARM64_ERRATUM_4311569 from ARM64_CPUCAP_SYSTEM_FEATURE to
ARM64_CPUCAP_SOC_ERRATUM since it is a SoC-level property already
determined at boot. This changes its scope from SCOPE_SYSTEM to
SCOPE_BOOT_CPU, so the workaround is now enabled before the secondary
CPUs are brought up. This is safe as the erratum is enabled via an
early_param, parsed before the boot CPU capabilities are detected.

Co-developed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Catalin Marinas 2026-10-10 01:19:45 +08:00
parent 93f51579e7
commit cea68e7489
3 changed files with 29 additions and 2 deletions
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24
arch/arm64/include/asm/cpufeature.h
View File

@ -187,6 +187,10 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0;
* b) SCOPE_LOCAL_CPU, SCOPE_SYSTEM: All CPUs hotplugged on by the
* user after the kernel boot are verified against the capability.
*
* SCOPE_BOOT_CPU and SCOPE_SYSTEM capabilities with
* ARM64_CPUCAP_PROBE_ONCE are not matched again on these CPUs. They
* take the state already detected, so there cannot be a conflict.
*
* If there is a conflict, the kernel takes an action, based on the
* severity (e.g, a CPU could be prevented from booting or cause a
* kernel panic). The CPU is allowed to "affect" the state of the
@ -266,6 +270,13 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0;
#define SCOPE_BOOT_CPU ARM64_CPUCAP_SCOPE_BOOT_CPU
#define SCOPE_ALL ARM64_CPUCAP_SCOPE_MASK
/*
* matches() is called only once, when the capability is detected, and the
* result applies to all CPUs. Secondary and late CPUs are not checked for
* conflicts but cpu_enable() is still called on each of them. It has no
* effect on SCOPE_LOCAL_CPU capabilities.
*/
#define ARM64_CPUCAP_PROBE_ONCE ((u16)BIT(3))
/*
* Is it permitted for a late CPU to have this capability when system
* hasn't already enabled it ?
@ -293,6 +304,13 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0;
*/
#define ARM64_CPUCAP_LOCAL_CPU_ERRATUM \
(ARM64_CPUCAP_SCOPE_LOCAL_CPU | ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU)
/*
* SoC (not CPU) errata workarounds. The erratum is probed once on the boot
* CPU, before the secondary CPUs are brought up, and no secondary or late CPU
* can conflict with it.
*/
#define ARM64_CPUCAP_SOC_ERRATUM \
(ARM64_CPUCAP_SCOPE_BOOT_CPU | ARM64_CPUCAP_PROBE_ONCE)
/*
* 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
@ -414,6 +432,12 @@ static inline bool cpucap_match_all_early_cpus(const struct arm64_cpu_capabiliti
return cap->type & ARM64_CPUCAP_MATCH_ALL_EARLY_CPUS;
}
static inline bool cpucap_probe_once(const struct arm64_cpu_capabilities *cap)
{
return (cap->type & ARM64_CPUCAP_PROBE_ONCE) &&
!(cap->type & ARM64_CPUCAP_SCOPE_LOCAL_CPU);
}
/*
* Generic helper for handling capabilities with multiple (match,enable) pairs
* of call backs, sharing the same capability bit.

2
arch/arm64/kernel/cpu_errata.c
View File

@ -971,7 +971,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
#ifdef CONFIG_ARM64_ERRATUM_4311569
{
.capability = ARM64_WORKAROUND_4311569,
.type = ARM64_CPUCAP_SYSTEM_FEATURE,
.type = ARM64_CPUCAP_SOC_ERRATUM,
.matches = need_arm_si_l1_workaround_4311569,
},
#endif

5
arch/arm64/kernel/cpufeature.c
View File

@ -3694,8 +3694,11 @@ static void verify_local_cpu_caps(u16 scope_mask)
if (!caps || !(caps->type & scope_mask))
continue;
cpu_has_cap = caps->matches(caps, SCOPE_LOCAL_CPU);
system_has_cap = cpus_have_cap(caps->capability);
if (cpucap_probe_once(caps))
cpu_has_cap = system_has_cap;
else
cpu_has_cap = caps->matches(caps, SCOPE_LOCAL_CPU);
if (system_has_cap) {
/*