[for-stable-4.14,45/48] arm64: ssbs: Don't treat CPUs with SSBS as unaffected by SSB

Message ID 20191024124833.4158-46-ard.biesheuvel@linaro.org
State New
Headers show
Series
  • arm64 spec mitigation backports
Related show

Commit Message

Ard Biesheuvel Oct. 24, 2019, 12:48 p.m.
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>

---
 arch/arm64/kernel/cpu_errata.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

-- 
2.20.1

Patch

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 2898130c3156..55526738ccbc 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -333,15 +333,17 @@  static bool has_ssbd_mitigation(const struct arm64_cpu_capabilities *entry,
 
 	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)