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Subject[PATCH 1/2] arm64: capabilities: Allow flexibility in scope
Date
So far we have restricted the scopes for the capabilities
as follows :
1) Errata workaround check are run all CPUs (i.e, always
SCOPE_LOCAL_CPU)
2) Arm64 features are run only once after the sanitised
feature registers are available using the SCOPE_SYSTEM.

This prevents detecting cpu features that can be detected
on one or more CPUs with SCOPE_LOCAL_CPU (e.g KPTI). Similarly
for errata workaround with SCOPE_SYSTEM.

This patch makes sure that we allow flexibility of having
any scope for a capability. So, we now run through both
arm64_features and arm64_errata in two phases for detection:

a) with SCOPE_LOCAL_CPU filter on each boot time enabled
CPUs.
b) with SCOPE_SYSTEM filter only once after all boot time
enabled CPUs are active.

Cc: Dave Martin <dave.martin@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
arch/arm64/kernel/cpufeature.c | 33 ++++++++++++++++++++++++---------
1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 61d4c3cfb1cc..e1a56fa889a5 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -505,6 +505,7 @@ static void __init init_cpu_ftr_reg(u32 sys_reg, u64 new)

extern const struct arm64_cpu_capabilities arm64_errata[];
static void update_cpu_errata_workarounds(void);
+static void update_cpu_local_features(void);

void __init init_cpu_features(struct cpuinfo_arm64 *info)
{
@@ -554,6 +555,7 @@ void __init init_cpu_features(struct cpuinfo_arm64 *info)
* initialised the cpu feature infrastructure.
*/
update_cpu_errata_workarounds();
+ update_cpu_local_features();
}

static void update_cpu_ftr_reg(struct arm64_ftr_reg *reg, u64 new)
@@ -1387,13 +1389,15 @@ static void verify_local_cpu_errata_workarounds(void)
static void update_cpu_errata_workarounds(void)
{
update_cpu_capabilities(arm64_errata,
- ARM64_CPUCAP_SCOPE_ALL,
+ ARM64_CPUCAP_SCOPE_LOCAL_CPU,
"enabling workaround for");
}

-static void __init enable_errata_workarounds(void)
+static void update_cpu_local_features(void)
{
- enable_cpu_capabilities(arm64_errata, ARM64_CPUCAP_SCOPE_ALL);
+ update_cpu_capabilities(arm64_features,
+ ARM64_CPUCAP_SCOPE_LOCAL_CPU,
+ "detected feature:");
}

/*
@@ -1430,23 +1434,34 @@ void check_local_cpu_capabilities(void)

/*
* If we haven't finalised the system capabilities, this CPU gets
- * a chance to update the errata work arounds.
+ * a chance to update the errata work arounds and local CPU features.
* Otherwise, this CPU should verify that it has all the system
* advertised capabilities.
*/
- if (!sys_caps_initialised)
+ if (!sys_caps_initialised) {
update_cpu_errata_workarounds();
- else
+ update_cpu_local_features();
+ } else {
verify_local_cpu_capabilities();
+ }
}

static void __init setup_feature_capabilities(void)
{
update_cpu_capabilities(arm64_features,
- ARM64_CPUCAP_SCOPE_ALL, "detected feature:");
+ ARM64_CPUCAP_SCOPE_SYSTEM,
+ "detected feature:");
enable_cpu_capabilities(arm64_features, ARM64_CPUCAP_SCOPE_ALL);
}

+static void __init setup_errata_workarounds(void)
+{
+ update_cpu_capabilities(arm64_errata,
+ ARM64_CPUCAP_SCOPE_SYSTEM,
+ "enabling workaround for");
+ enable_cpu_capabilities(arm64_errata, ARM64_CPUCAP_SCOPE_ALL);
+}
+
DEFINE_STATIC_KEY_FALSE(arm64_const_caps_ready);
EXPORT_SYMBOL(arm64_const_caps_ready);

@@ -1468,9 +1483,9 @@ void __init setup_cpu_features(void)
u32 cwg;
int cls;

- /* Set the CPU feature capabilies */
+ /* Finalise the CPU capabilities */
setup_feature_capabilities();
- enable_errata_workarounds();
+ setup_errata_workarounds();
mark_const_caps_ready();
setup_elf_hwcaps(arm64_elf_hwcaps);

--
2.14.3
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