[v4.4,V2,18/43] arm64: Rearrange CPU errata workaround checks

Message ID 4c595dbb19c7b70c007b6bfa068c1b22dca4bdec.1562908075.git.viresh.kumar@linaro.org
State New
Headers show
Series
  • V4.4 backport of arm64 Spectre patches
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Commit Message

Viresh Kumar July 12, 2019, 5:28 a.m.
From: Suzuki K Poulose <suzuki.poulose@arm.com>


commit c47a1900ad710fd2c97127e2ba19da1df79cf733 upstream.

Right now we run through the work around checks on a CPU
from __cpuinfo_store_cpu. There are some problems with that:

1) We initialise the system wide CPU feature registers only after the
Boot CPU updates its cpuinfo. Now, if a work around depends on the
variance of a CPU ID feature (e.g, check for Cache Line size mismatch),
we have no way of performing it cleanly for the boot CPU.

2) It is out of place, invoked from __cpuinfo_store_cpu() in cpuinfo.c. It
is not an obvious place for that.

This patch rearranges the CPU specific capability(aka work around) checks.

1) At the moment we use verify_local_cpu_capabilities() to check if a new
CPU has all the system advertised features. Use this for the secondary CPUs
to perform the work around check. For that we rename
  verify_local_cpu_capabilities() => check_local_cpu_capabilities()
which:

   If the system wide capabilities haven't been initialised (i.e, the CPU
   is activated at the boot), update the system wide detected work arounds.

   Otherwise (i.e a CPU hotplugged in later) verify that this CPU conforms to the
   system wide capabilities.

2) Boot CPU updates the work arounds from smp_prepare_boot_cpu() after we have
initialised the system wide CPU feature values.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>

Signed-off-by: Will Deacon <will.deacon@arm.com>

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

---
 arch/arm64/include/asm/cpufeature.h |  8 +-------
 arch/arm64/kernel/cpufeature.c      | 23 +++++++++++++++--------
 arch/arm64/kernel/cpuinfo.c         |  2 --
 arch/arm64/kernel/smp.c             |  8 +++++++-
 4 files changed, 23 insertions(+), 18 deletions(-)

-- 
2.21.0.rc0.269.g1a574e7a288b

Patch

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 0267bab6ac18..1bc51f8835e5 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -177,13 +177,7 @@  void __init enable_errata_workarounds(void);
 
 void verify_local_cpu_errata(void);
 
-#ifdef CONFIG_HOTPLUG_CPU
-void verify_local_cpu_capabilities(void);
-#else
-static inline void verify_local_cpu_capabilities(void)
-{
-}
-#endif
+void check_local_cpu_capabilities(void);
 
 u64 read_system_reg(u32 id);
 
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 7773bea6927e..c74df3ca000e 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -860,18 +860,11 @@  static inline void set_sys_caps_initialised(void)
  * cannot do anything to fix it up and could cause unexpected failures. So
  * we park the CPU.
  */
-void verify_local_cpu_capabilities(void)
+static void verify_local_cpu_capabilities(void)
 {
 	int i;
 	const struct arm64_cpu_capabilities *caps;
 
-	/*
-	 * If we haven't computed the system capabilities, there is nothing
-	 * to verify.
-	 */
-	if (!sys_caps_initialised)
-		return;
-
 	verify_local_cpu_errata();
 
 	caps = arm64_features;
@@ -902,6 +895,20 @@  void verify_local_cpu_capabilities(void)
 	}
 }
 
+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.
+	 * Otherwise, this CPU should verify that it has all the system
+	 * advertised capabilities.
+	 */
+	if (!sys_caps_initialised)
+		check_local_cpu_errata();
+	else
+		verify_local_cpu_capabilities();
+}
+
 #else	/* !CONFIG_HOTPLUG_CPU */
 
 static inline void set_sys_caps_initialised(void)
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 0166cfbc866c..13e659fda04a 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -239,8 +239,6 @@  static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
 	info->reg_mvfr2 = read_cpuid(MVFR2_EL1);
 
 	cpuinfo_detect_icache_policy(info);
-
-	check_local_cpu_errata();
 }
 
 void cpuinfo_store_cpu(void)
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 752b53daac23..7a9eff0d1ebe 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -161,7 +161,7 @@  asmlinkage notrace void secondary_start_kernel(void)
 	 * this CPU ticks all of those. If it doesn't, the CPU will
 	 * fail to come online.
 	 */
-	verify_local_cpu_capabilities();
+	check_local_cpu_capabilities();
 
 	if (cpu_ops[cpu]->cpu_postboot)
 		cpu_ops[cpu]->cpu_postboot();
@@ -360,6 +360,12 @@  void __init smp_prepare_boot_cpu(void)
 {
 	set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 	cpuinfo_store_boot_cpu();
+	/*
+	 * Run the errata work around checks on the boot CPU, once we have
+	 * initialised the cpu feature infrastructure from
+	 * cpuinfo_store_boot_cpu() above.
+	 */
+	check_local_cpu_errata();
 }
 
 static u64 __init of_get_cpu_mpidr(struct device_node *dn)