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Subject[PATCH v3 18/22] arm64: capabilities: Add support for checks based on a list of MIDRs
Date
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>
Reviewed-by: Dave Martin <dave.martin@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
arch/arm64/include/asm/cpufeature.h | 1 +
arch/arm64/include/asm/cputype.h | 8 +++++
arch/arm64/kernel/cpu_errata.c | 61 +++++++++++++++++++++----------------
arch/arm64/kernel/cpufeature.c | 10 +++---
4 files changed, 50 insertions(+), 30 deletions(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index e47f39f62440..3ab1c3422f14 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -297,6 +297,7 @@ struct arm64_cpu_capabilities {
void (*cpu_enable)(const struct arm64_cpu_capabilities *cap);
union {
struct midr_range midr_range; /* To be used for erratum handling only */
+ const struct midr_range *midr_range_list;
struct { /* Feature register checking */
u32 sys_reg;
u8 field_pos;
diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
index 6c45acb6ef38..26bc5b302060 100644
--- a/arch/arm64/include/asm/cputype.h
+++ b/arch/arm64/include/asm/cputype.h
@@ -145,6 +145,14 @@ static inline bool is_midr_in_range(u32 midr, struct midr_range const *range)
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
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 5f903e37a267..a602a3049404 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -28,6 +28,13 @@ is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope)
return is_midr_in_range(read_cpuid_id(), &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 __maybe_unused
is_kryo_midr(const struct arm64_cpu_capabilities *entry, int scope)
{
@@ -235,6 +242,10 @@ qcom_enable_link_stack_sanitization(const struct arm64_cpu_capabilities *entry)
.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)
@@ -248,6 +259,29 @@ qcom_enable_link_stack_sanitization(const struct arm64_cpu_capabilities *entry)
.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_psci_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) || \
@@ -382,22 +416,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
#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),
+ ERRATA_MIDR_RANGE_LIST(arm64_bp_harden_psci_cpus),
.cpu_enable = enable_smccc_arch_workaround_1,
},
{
@@ -409,16 +428,6 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
.capability = ARM64_HARDEN_BP_POST_GUEST_EXIT,
ERRATA_MIDR_ALL_VERSIONS(MIDR_QCOM_FALKOR_V1),
},
- {
- .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),
- .cpu_enable = enable_smccc_arch_workaround_1,
- },
#endif
{
}
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index f66e66c79916..9eb9e9570468 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -864,6 +864,11 @@ static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */
static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
int scope)
{
+ /* 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),
+ };
char const *str = "command line option";

/*
@@ -888,11 +893,8 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
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:
+ if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list))
return false;
- }

/* Defer to CPU feature registers */
return !has_cpuid_feature(entry, scope);
--
2.14.3
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