From: Marc Zyngier <marc.zyngier@arm.com>
To: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Cc: Will Deacon <will.deacon@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andy Lutomirski <luto@kernel.org>,
Kees Cook <keescook@chromium.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Christoffer Dall <christoffer.dall@arm.com>,
Randy Dunlap <rdunlap@infradead.org>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Julien Grall <julien.grall@arm.com>,
Mark Rutland <mark.rutland@arm.com>
Subject: [PATCH v2 04/17] arm64: Add ARCH_WORKAROUND_2 probing
Date: Tue, 29 May 2018 13:11:08 +0100 [thread overview]
Message-ID: <20180529121121.24927-5-marc.zyngier@arm.com> (raw)
In-Reply-To: <20180529121121.24927-1-marc.zyngier@arm.com>
As for Spectre variant-2, we rely on SMCCC 1.1 to provide the
discovery mechanism for detecting the SSBD mitigation.
A new capability is also allocated for that purpose, and a
config option.
Reviewed-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm64/Kconfig | 9 ++++++
arch/arm64/include/asm/cpucaps.h | 3 +-
arch/arm64/kernel/cpu_errata.c | 69 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 80 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index eb2cf4938f6d..b2103b4df467 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -938,6 +938,15 @@ config HARDEN_EL2_VECTORS
If unsure, say Y.
+config ARM64_SSBD
+ bool "Speculative Store Bypass Disable" if EXPERT
+ default y
+ help
+ This enables mitigation of the bypassing of previous stores
+ by speculative loads.
+
+ If unsure, say Y.
+
menuconfig ARMV8_DEPRECATED
bool "Emulate deprecated/obsolete ARMv8 instructions"
depends on COMPAT
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index bc51b72fafd4..8a699c708fc9 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -48,7 +48,8 @@
#define ARM64_HAS_CACHE_IDC 27
#define ARM64_HAS_CACHE_DIC 28
#define ARM64_HW_DBM 29
+#define ARM64_SSBD 30
-#define ARM64_NCAPS 30
+#define ARM64_NCAPS 31
#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index d1a7a68dc142..0c76c9f176bb 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -256,6 +256,67 @@ void __init arm64_update_smccc_conduit(struct alt_instr *alt,
*updptr = cpu_to_le32(insn);
}
+
+static void arm64_set_ssbd_mitigation(bool state)
+{
+ switch (psci_ops.conduit) {
+ case PSCI_CONDUIT_HVC:
+ arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_WORKAROUND_2, state, NULL);
+ break;
+
+ case PSCI_CONDUIT_SMC:
+ arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, state, NULL);
+ break;
+
+ default:
+ WARN_ON_ONCE(1);
+ break;
+ }
+}
+
+static bool has_ssbd_mitigation(const struct arm64_cpu_capabilities *entry,
+ int scope)
+{
+ struct arm_smccc_res res;
+ bool supported = true;
+
+ WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
+
+ if (psci_ops.smccc_version == SMCCC_VERSION_1_0)
+ return false;
+
+ /*
+ * The probe function return value is either negative
+ * (unsupported or mitigated), positive (unaffected), or zero
+ * (requires mitigation). We only need to do anything in the
+ * last case.
+ */
+ switch (psci_ops.conduit) {
+ case PSCI_CONDUIT_HVC:
+ arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
+ ARM_SMCCC_ARCH_WORKAROUND_2, &res);
+ if ((int)res.a0 != 0)
+ supported = false;
+ break;
+
+ case PSCI_CONDUIT_SMC:
+ arm_smccc_1_1_smc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
+ ARM_SMCCC_ARCH_WORKAROUND_2, &res);
+ if ((int)res.a0 != 0)
+ supported = false;
+ break;
+
+ default:
+ supported = false;
+ }
+
+ if (supported) {
+ __this_cpu_write(arm64_ssbd_callback_required, 1);
+ arm64_set_ssbd_mitigation(true);
+ }
+
+ return supported;
+}
#endif /* CONFIG_ARM64_SSBD */
#define CAP_MIDR_RANGE(model, v_min, r_min, v_max, r_max) \
@@ -513,6 +574,14 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
ERRATA_MIDR_RANGE_LIST(arm64_harden_el2_vectors),
},
+#endif
+#ifdef CONFIG_ARM64_SSBD
+ {
+ .desc = "Speculative Store Bypass Disable",
+ .capability = ARM64_SSBD,
+ .type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
+ .matches = has_ssbd_mitigation,
+ },
#endif
{
}
--
2.14.2
next prev parent reply other threads:[~2018-05-29 12:11 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-29 12:11 [PATCH v2 00/17] arm64 SSBD (aka Spectre-v4) mitigation Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 01/17] arm/arm64: smccc: Add SMCCC-specific return codes Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 02/17] arm64: Call ARCH_WORKAROUND_2 on transitions between EL0 and EL1 Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 03/17] arm64: Add per-cpu infrastructure to call ARCH_WORKAROUND_2 Marc Zyngier
2018-05-29 12:11 ` Marc Zyngier [this message]
2018-05-29 13:39 ` [PATCH v2 04/17] arm64: Add ARCH_WORKAROUND_2 probing Suzuki K Poulose
2018-05-29 12:11 ` [PATCH v2 05/17] arm64: Add 'ssbd' command-line option Marc Zyngier
2018-06-09 12:53 ` Jon Masters
2018-06-09 13:19 ` Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 06/17] arm64: ssbd: Add global mitigation state accessor Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 07/17] arm64: ssbd: Skip apply_ssbd if not using dynamic mitigation Marc Zyngier
2018-06-09 13:03 ` Jon Masters
2018-06-09 13:21 ` Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 08/17] arm64: ssbd: Restore mitigation status on CPU resume Marc Zyngier
2018-05-29 13:35 ` Mark Rutland
2018-05-29 12:11 ` [PATCH v2 09/17] arm64: ssbd: Introduce thread flag to control userspace mitigation Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 10/17] arm64: ssbd: Add prctl interface for per-thread mitigation Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 11/17] arm64: KVM: Add HYP per-cpu accessors Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 12/17] arm64: KVM: Add ARCH_WORKAROUND_2 support for guests Marc Zyngier
2018-06-09 13:09 ` Jon Masters
2018-06-09 13:21 ` Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 13/17] arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 14/17] arm64: KVM: Add ARCH_WORKAROUND_2 discovery through ARCH_FEATURES_FUNC_ID Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 15/17] arm64: Add test_and_clear_flag and set_flag atomic assembler primitives Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 16/17] arm64: ssbd: Enable delayed setting of TIF_SSBD Marc Zyngier
2018-05-29 12:11 ` [PATCH v2 17/17] arm64: ssbd: Implement arch_seccomp_spec_mitigate Marc Zyngier
2018-05-30 15:58 ` [PATCH v2 00/17] arm64 SSBD (aka Spectre-v4) mitigation Will Deacon
2018-05-31 16:41 ` Catalin Marinas
2018-05-31 16:55 ` Marc Zyngier
2018-06-09 13:16 ` Jon Masters
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