diff options
Diffstat (limited to 'arch/arm64/kernel/cpu_errata.c')
| -rw-r--r-- | arch/arm64/kernel/cpu_errata.c | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index cde948991d68..3deb01c6ed49 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -68,11 +68,32 @@ static bool has_mismatched_cache_type(const struct arm64_cpu_capabilities *entry, int scope) { - u64 mask = arm64_ftr_reg_ctrel0.strict_mask;; + u64 mask = arm64_ftr_reg_ctrel0.strict_mask; + u64 sys = arm64_ftr_reg_ctrel0.sys_val & mask; + u64 ctr_raw, ctr_real; WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible()); - return (read_cpuid_cachetype() & mask) != - (arm64_ftr_reg_ctrel0.sys_val & mask); + + /* + * We want to make sure that all the CPUs in the system expose + * a consistent CTR_EL0 to make sure that applications behaves + * correctly with migration. + * + * If a CPU has CTR_EL0.IDC but does not advertise it via CTR_EL0 : + * + * 1) It is safe if the system doesn't support IDC, as CPU anyway + * reports IDC = 0, consistent with the rest. + * + * 2) If the system has IDC, it is still safe as we trap CTR_EL0 + * access on this CPU via the ARM64_HAS_CACHE_IDC capability. + * + * So, we need to make sure either the raw CTR_EL0 or the effective + * CTR_EL0 matches the system's copy to allow a secondary CPU to boot. + */ + ctr_raw = read_cpuid_cachetype() & mask; + ctr_real = read_cpuid_effective_cachetype() & mask; + + return (ctr_real != sys) && (ctr_raw != sys); } static void |