[PATCH 12/19] arm64: Treat SSBS as a non-strict system feature
Will Deacon
will at kernel.org
Fri Sep 18 12:47:22 EDT 2020
If all CPUs discovered during boot have SSBS, then spectre-v4 will be
considered to be "mitigated". However, we still allow late CPUs without
SSBS to be onlined, albeit with a "SANITY CHECK" warning. This is
problematic for userspace because it means that the system can quietly
transition to "Vulnerable" at runtime.
Avoid this by treating SSBS as a non-strict system feature: if all of
the CPUs discovered during boot have SSBS, then late arriving secondaries
better have it as well.
Signed-off-by: Will Deacon <will at kernel.org>
---
arch/arm64/kernel/cpufeature.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 4bb45b1d4ae4..033e6c952705 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -227,7 +227,7 @@ static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = {
static const struct arm64_ftr_bits ftr_id_aa64pfr1[] = {
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_MPAMFRAC_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_RASFRAC_SHIFT, 4, 0),
- ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_SSBS_SHIFT, 4, ID_AA64PFR1_SSBS_PSTATE_NI),
+ ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR1_SSBS_SHIFT, 4, ID_AA64PFR1_SSBS_PSTATE_NI),
ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_BTI),
FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_BT_SHIFT, 4, 0),
ARM64_FTR_END,
@@ -487,7 +487,7 @@ static const struct arm64_ftr_bits ftr_id_pfr1[] = {
};
static const struct arm64_ftr_bits ftr_id_pfr2[] = {
- ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_PFR2_SSBS_SHIFT, 4, 0),
+ ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_PFR2_SSBS_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_PFR2_CSV3_SHIFT, 4, 0),
ARM64_FTR_END,
};
@@ -1977,7 +1977,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
{
.desc = "Speculative Store Bypassing Safe (SSBS)",
.capability = ARM64_SSBS,
- .type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
.matches = has_cpuid_feature,
.sys_reg = SYS_ID_AA64PFR1_EL1,
.field_pos = ID_AA64PFR1_SSBS_SHIFT,
--
2.28.0.681.g6f77f65b4e-goog
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