[PATCH 4.9 11/43] arm64: capabilities: Add support for checks based on a list of MIDRs

Greg Kroah-Hartman
2022-04-06T19:52:15Z

From: Suzuki K Poulose <suzuki.poulose@arm.com>

[ Upstream commit be5b299830c63ed76e0357473c4218c85fb388b3 ]

Add helpers for detecting an errata on list of midr ranges
of affected CPUs, with the same work around.

Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Dave Martin <dave.martin@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
[ardb: add Cortex-A35 to kpti_safe_list[] as well]
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/include/asm/cpufeature.h | 1
arch/arm64/include/asm/cputype.h | 9 +++++
arch/arm64/kernel/cpu_errata.c | 62 ++++++++++++++++++++----------------
arch/arm64/kernel/cpufeature.c | 21 ++++++------
4 files changed, 58 insertions(+), 35 deletions(-)

--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -233,6 +233,7 @@ struct arm64_cpu_capabilities {
struct midr_range midr_range;
};

+ const struct midr_range *midr_range_list;
struct { /* Feature register checking */
u32 sys_reg;
u8 field_pos;
--- a/arch/arm64/include/asm/cputype.h
+++ b/arch/arm64/include/asm/cputype.h
@@ -143,6 +143,15 @@ static inline bool is_midr_in_range(u32
range->rv_min, range->rv_max);
}

+static inline bool
+is_midr_in_range_list(u32 midr, struct midr_range const *ranges)
+{
+ while (ranges->model)
+ if (is_midr_in_range(midr, ranges++))
+ return true;
+ return false;
+}
+
/*
* The CPU ID never changes at run time, so we might as well tell the
* compiler that it's constant. Use this function to read the CPU ID
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -33,6 +33,14 @@ is_affected_midr_range(const struct arm6
return is_midr_in_range(midr, &entry->midr_range);
}

+static bool __maybe_unused
+is_affected_midr_range_list(const struct arm64_cpu_capabilities *entry,
+ int scope)
+{
+ WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
+ return is_midr_in_range_list(read_cpuid_id(), entry->midr_range_list);
+}
+
static bool
has_mismatched_cache_type(const struct arm64_cpu_capabilities *entry,
int scope)
@@ -383,6 +391,10 @@ static bool has_ssbd_mitigation(const st
.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM, \
CAP_MIDR_RANGE(model, v_min, r_min, v_max, r_max)

+#define CAP_MIDR_RANGE_LIST(list) \
+ .matches = is_affected_midr_range_list, \
+ .midr_range_list = list
+
/* Errata affecting a range of revisions of given model variant */
#define ERRATA_MIDR_REV_RANGE(m, var, r_min, r_max) \
ERRATA_MIDR_RANGE(m, var, r_min, var, r_max)
@@ -396,6 +408,29 @@ static bool has_ssbd_mitigation(const st
.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM, \
CAP_MIDR_ALL_VERSIONS(model)

+/* Errata affecting a list of midr ranges, with same work around */
+#define ERRATA_MIDR_RANGE_LIST(midr_list) \
+ .type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM, \
+ CAP_MIDR_RANGE_LIST(midr_list)
+
+#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
+
+/*
+ * List of CPUs where we need to issue a psci call to
+ * harden the branch predictor.
+ */
+static const struct midr_range arm64_bp_harden_smccc_cpus[] = {
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A57),
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A72),
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A73),
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A75),
+ MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
+ MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
+ {},
+};
+
+#endif
+
const struct arm64_cpu_capabilities arm64_errata[] = {
#if defined(CONFIG_ARM64_ERRATUM_826319) || \
defined(CONFIG_ARM64_ERRATUM_827319) || \
@@ -486,32 +521,7 @@ const struct arm64_cpu_capabilities arm6
#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
{
.capability = ARM64_HARDEN_BRANCH_PREDICTOR,
- ERRATA_MIDR_ALL_VERSIONS(MIDR_CORTEX_A57),
- .cpu_enable = enable_smccc_arch_workaround_1,
- },
- {
- .capability = ARM64_HARDEN_BRANCH_PREDICTOR,
- ERRATA_MIDR_ALL_VERSIONS(MIDR_CORTEX_A72),
- .cpu_enable = enable_smccc_arch_workaround_1,
- },
- {
- .capability = ARM64_HARDEN_BRANCH_PREDICTOR,
- ERRATA_MIDR_ALL_VERSIONS(MIDR_CORTEX_A73),
- .cpu_enable = enable_smccc_arch_workaround_1,
- },
- {
- .capability = ARM64_HARDEN_BRANCH_PREDICTOR,
- ERRATA_MIDR_ALL_VERSIONS(MIDR_CORTEX_A75),
- .cpu_enable = enable_smccc_arch_workaround_1,
- },
- {
- .capability = ARM64_HARDEN_BRANCH_PREDICTOR,
- ERRATA_MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
- .cpu_enable = enable_smccc_arch_workaround_1,
- },
- {
- .capability = ARM64_HARDEN_BRANCH_PREDICTOR,
- ERRATA_MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
+ ERRATA_MIDR_RANGE_LIST(arm64_bp_harden_smccc_cpus),
.cpu_enable = enable_smccc_arch_workaround_1,
},
#endif
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -767,6 +767,17 @@ static int __kpti_forced; /* 0: not forc
static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
int __unused)
{
+ /* List of CPUs that are not vulnerable and don't need KPTI */
+ static const struct midr_range kpti_safe_list[] = {
+ MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
+ MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A35),
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A53),
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A55),
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A57),
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A72),
+ MIDR_ALL_VERSIONS(MIDR_CORTEX_A73),
+ };
char const *str = "command line option";
u64 pfr0 = read_system_reg(SYS_ID_AA64PFR0_EL1);

@@ -792,16 +803,8 @@ static bool unmap_kernel_at_el0(const st
return true;

/* Don't force KPTI for CPUs that are not vulnerable */
- switch (read_cpuid_id() & MIDR_CPU_MODEL_MASK) {
- case MIDR_CAVIUM_THUNDERX2:
- case MIDR_BRCM_VULCAN:
- case MIDR_CORTEX_A53:
- case MIDR_CORTEX_A55:
- case MIDR_CORTEX_A57:
- case MIDR_CORTEX_A72:
- case MIDR_CORTEX_A73:
+ if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list))
return false;
- }

/* Defer to CPU feature registers */
return !cpuid_feature_extract_unsigned_field(pfr0,