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Subject[PATCH 4.19 102/114] arm64: ssbs: Dont treat CPUs with SSBS as unaffected by SSB
Date
From: Will Deacon <will.deacon@arm.com>

[ Upstream commit eb337cdfcd5dd3b10522c2f34140a73a4c285c30 ]

SSBS provides a relatively cheap mitigation for SSB, but it is still a
mitigation and its presence does not indicate that the CPU is unaffected
by the vulnerability.

Tweak the mitigation logic so that we report the correct string in sysfs.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/kernel/cpu_errata.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -341,15 +341,17 @@ static bool has_ssbd_mitigation(const st

WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());

+ /* delay setting __ssb_safe until we get a firmware response */
+ if (is_midr_in_range_list(read_cpuid_id(), entry->midr_range_list))
+ this_cpu_safe = true;
+
if (this_cpu_has_cap(ARM64_SSBS)) {
+ if (!this_cpu_safe)
+ __ssb_safe = false;
required = false;
goto out_printmsg;
}

- /* delay setting __ssb_safe until we get a firmware response */
- if (is_midr_in_range_list(read_cpuid_id(), entry->midr_range_list))
- this_cpu_safe = true;
-
if (psci_ops.smccc_version == SMCCC_VERSION_1_0) {
ssbd_state = ARM64_SSBD_UNKNOWN;
if (!this_cpu_safe)

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