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Subject[PATCH v3 06/22] arm64: capabilities: Unify the verification
Date
Now that each capability describes how to treat the conflicts
of CPU cap state vs System wide cap state, we can unify the
verification logic to a single place.

Reviewed-by: Dave Martin <dave.martin@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
arch/arm64/kernel/cpufeature.c | 89 ++++++++++++++++++++++++++----------------
1 file changed, 56 insertions(+), 33 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 7df82c9daeb0..48ed6d71094f 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1269,6 +1269,56 @@ static void __init enable_cpu_capabilities(const struct arm64_cpu_capabilities *
}
}

+/*
+ * Run through the list of capabilities to check for conflicts.
+ * If the system has already detected a capability, take necessary
+ * action on this CPU.
+ *
+ * Returns "false" on conflicts.
+ */
+static bool __verify_local_cpu_caps(const struct arm64_cpu_capabilities *caps_list)
+{
+ bool cpu_has_cap, system_has_cap;
+ const struct arm64_cpu_capabilities *caps = caps_list;
+
+ for (; caps->matches; caps++) {
+ cpu_has_cap = __this_cpu_has_cap(caps_list, caps->capability);
+ system_has_cap = cpus_have_cap(caps->capability);
+
+ if (system_has_cap) {
+ /*
+ * Check if the new CPU misses an advertised feature, which is not
+ * safe to miss.
+ */
+ if (!cpu_has_cap && !cpucap_late_cpu_optional(caps))
+ break;
+ /*
+ * We have to issue cpu_enable() irrespective of whether the CPU
+ * has it or not, as it is enabeld system wide. It is upto
+ * the call back to take appropriate action on this CPU.
+ */
+ if (caps->cpu_enable)
+ caps->cpu_enable(caps);
+ } else {
+ /*
+ * Check if the CPU has this capability if it isn't safe to
+ * have when the system doesn't.
+ */
+ if (cpu_has_cap && !cpucap_late_cpu_permitted(caps))
+ break;
+ }
+ }
+
+ if (caps->matches) {
+ pr_crit("CPU%d: Detected conflict for capability %d (%s), System: %d, CPU: %d\n",
+ smp_processor_id(), caps->capability,
+ caps->desc, system_has_cap, cpu_has_cap);
+ return false;
+ }
+
+ return true;
+}
+
/*
* Check for CPU features that are used in early boot
* based on the Boot CPU value.
@@ -1291,25 +1341,10 @@ verify_local_elf_hwcaps(const struct arm64_cpu_capabilities *caps)
}
}

-static void
-verify_local_cpu_features(const struct arm64_cpu_capabilities *caps_list)
+static void verify_local_cpu_features(void)
{
- const struct arm64_cpu_capabilities *caps = caps_list;
- for (; caps->matches; caps++) {
- if (!cpus_have_cap(caps->capability))
- continue;
- /*
- * If the new CPU misses an advertised feature, we cannot proceed
- * further, park the cpu.
- */
- if (!__this_cpu_has_cap(caps_list, caps->capability)) {
- pr_crit("CPU%d: missing feature: %s\n",
- smp_processor_id(), caps->desc);
- cpu_die_early();
- }
- if (caps->cpu_enable)
- caps->cpu_enable(caps);
- }
+ if (!__verify_local_cpu_caps(arm64_features))
+ cpu_die_early();
}

static void verify_sve_features(void)
@@ -1336,20 +1371,8 @@ static void verify_sve_features(void)
*/
static void verify_local_cpu_errata_workarounds(void)
{
- const struct arm64_cpu_capabilities *caps = arm64_errata;
-
- for (; caps->matches; caps++) {
- if (cpus_have_cap(caps->capability)) {
- if (caps->cpu_enable)
- caps->cpu_enable(caps);
- } else if (caps->matches(caps, SCOPE_LOCAL_CPU)) {
- pr_crit("CPU%d: Requires work around for %s, not detected"
- " at boot time\n",
- smp_processor_id(),
- caps->desc ? : "an erratum");
- cpu_die_early();
- }
- }
+ if (!__verify_local_cpu_caps(arm64_errata))
+ cpu_die_early();
}

static void update_cpu_errata_workarounds(void)
@@ -1373,7 +1396,7 @@ static void __init enable_errata_workarounds(void)
static void verify_local_cpu_capabilities(void)
{
verify_local_cpu_errata_workarounds();
- verify_local_cpu_features(arm64_features);
+ verify_local_cpu_features();
verify_local_elf_hwcaps(arm64_elf_hwcaps);

if (system_supports_32bit_el0())
--
2.14.3
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