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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Will Deacon <will.deacon@arm.com>,
	Jeremy Linton <jeremy.linton@arm.com>,
	Andre Przywara <andre.przywara@arm.com>,
	Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>
Subject: [RFC/RFT PATCH 15/16] arm64: ssbs: Don't treat CPUs with SSBS as unaffected by SSB
Date: Fri,  4 Oct 2019 14:04:29 +0200	[thread overview]
Message-ID: <20191004120430.11929-16-ard.biesheuvel@linaro.org> (raw)
In-Reply-To: <20191004120430.11929-1-ard.biesheuvel@linaro.org>

From: Will Deacon <will.deacon@arm.com>

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>
(cherry picked from commit eb337cdfcd5dd3b10522c2f34140a73a4c285c30)
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 arch/arm64/kernel/cpu_errata.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 534111eab864..a9ad932160cc 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -341,7 +341,13 @@ 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;
 	}
-- 
2.20.1


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  parent reply	other threads:[~2019-10-04 12:12 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-04 12:04 [RFC/RFT PATCH 00/16] arm64: backport SSBS handling to v4.19-stable Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 01/16] arm64: cpufeature: Detect SSBS and advertise to userspace Ard Biesheuvel
2019-10-08 14:35   ` Mark Rutland
2019-10-08 14:39     ` Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 02/16] arm64: ssbd: Add support for PSTATE.SSBS rather than trapping to EL3 Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 03/16] KVM: arm64: Set SCTLR_EL2.DSSBS if SSBD is forcefully disabled and !vhe Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 04/16] arm64: docs: Document SSBS HWCAP Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 05/16] arm64: fix SSBS sanitization Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 06/16] arm64: Add sysfs vulnerability show for spectre-v1 Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 07/16] arm64: add sysfs vulnerability show for meltdown Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 08/16] arm64: enable generic CPU vulnerabilites support Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 09/16] arm64: Provide a command line to disable spectre_v2 mitigation Ard Biesheuvel
2019-10-04 12:04   ` Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 10/16] arm64: Advertise mitigation of Spectre-v2, or lack thereof Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 11/16] arm64: Always enable spectre-v2 vulnerability detection Ard Biesheuvel
2019-10-08 15:05   ` Mark Rutland
2019-10-04 12:04 ` [RFC/RFT PATCH 12/16] arm64: Always enable ssb " Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 13/16] arm64: add sysfs vulnerability show for spectre-v2 Ard Biesheuvel
2019-10-04 12:04 ` [RFC/RFT PATCH 14/16] arm64: add sysfs vulnerability show for speculative store bypass Ard Biesheuvel
2019-10-04 12:04 ` Ard Biesheuvel [this message]
2019-10-04 12:04 ` [RFC/RFT PATCH 16/16] arm64: Force SSBS on context switch Ard Biesheuvel
2019-10-08  8:12 ` [RFC/RFT PATCH 00/16] arm64: backport SSBS handling to v4.19-stable Ard Biesheuvel
2019-10-08 15:09   ` Mark Rutland
2019-10-08 15:10     ` Ard Biesheuvel

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