arm64: Consolidate hotplug notifier for instruction emulation

As of now each insn_emulation has a cpu hotplug notifier that
enables/disables the CPU feature bit for the functionality. This
patch re-arranges the code, such that there is only one notifier
that runs through the list of registered emulation hooks and runs
their corresponding set_hw_mode.

We do nothing when a CPU is dying as we will set the appropriate bits
as it comes back online based on the state of the hooks.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Punit Agrawal <punit.agrawal@arm.com>
[catalin.marinas@arm.com: fix pr_warn compilation error]
[catalin.marinas@arm.com: remove unnecessary "insn" check]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 77 insertions, 48 deletions

diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
index c363671d7509..68b955e1fd99 100644
--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -19,6 +19,7 @@
 #include <asm/system_misc.h>
 #include <asm/traps.h>
 #include <asm/uaccess.h>
+#include <asm/cpufeature.h>
 
 #define CREATE_TRACE_POINTS
 #include "trace-events-emulation.h"
@@ -85,6 +86,57 @@ static void remove_emulation_hooks(struct insn_emulation_ops *ops)
         pr_notice("Removed %s emulation handler\n", ops->name);
 }
 
+static void enable_insn_hw_mode(void *data)
+{
+        struct insn_emulation *insn = (struct insn_emulation *)data;
+        if (insn->ops->set_hw_mode)
+                insn->ops->set_hw_mode(true);
+}
+
+static void disable_insn_hw_mode(void *data)
+{
+        struct insn_emulation *insn = (struct insn_emulation *)data;
+        if (insn->ops->set_hw_mode)
+                insn->ops->set_hw_mode(false);
+}
+
+/* Run set_hw_mode(mode) on all active CPUs */
+static int run_all_cpu_set_hw_mode(struct insn_emulation *insn, bool enable)
+{
+        if (!insn->ops->set_hw_mode)
+                return -EINVAL;
+        if (enable)
+                on_each_cpu(enable_insn_hw_mode, (void *)insn, true);
+        else
+                on_each_cpu(disable_insn_hw_mode, (void *)insn, true);
+        return 0;
+}
+
+/*
+ * Run set_hw_mode for all insns on a starting CPU.
+ * Returns:
+ *  0           - If all the hooks ran successfully.
+ * -EINVAL      - At least one hook is not supported by the CPU.
+ */
+static int run_all_insn_set_hw_mode(unsigned long cpu)
+{
+        int rc = 0;
+        unsigned long flags;
+        struct insn_emulation *insn;
+
+        raw_spin_lock_irqsave(&insn_emulation_lock, flags);
+        list_for_each_entry(insn, &insn_emulation, node) {
+                bool enable = (insn->current_mode == INSN_HW);
+                if (insn->ops->set_hw_mode && insn->ops->set_hw_mode(enable)) {
+                        pr_warn("CPU[%ld] cannot support the emulation of %s",
+                                cpu, insn->ops->name);
+                        rc = -EINVAL;
+                }
+        }
+        raw_spin_unlock_irqrestore(&insn_emulation_lock, flags);
+        return rc;
+}
+
 static int update_insn_emulation_mode(struct insn_emulation *insn,
                                        enum insn_emulation_mode prev)
 {
@@ -97,10 +149,8 @@ static int update_insn_emulation_mode(struct insn_emulation *insn,
                 remove_emulation_hooks(insn->ops);
                 break;
         case INSN_HW:
-                if (insn->ops->set_hw_mode) {
-                        insn->ops->set_hw_mode(false);
+                if (!run_all_cpu_set_hw_mode(insn, false))
                         pr_notice("Disabled %s support\n", insn->ops->name);
-                }
                 break;
         }
 
@@ -111,10 +161,9 @@ static int update_insn_emulation_mode(struct insn_emulation *insn,
                 register_emulation_hooks(insn->ops);
                 break;
         case INSN_HW:
-                if (insn->ops->set_hw_mode && insn->ops->set_hw_mode(true))
+                ret = run_all_cpu_set_hw_mode(insn, true);
+                if (!ret)
                         pr_notice("Enabled %s support\n", insn->ops->name);
-                else
-                        ret = -EINVAL;
                 break;
         }
 
@@ -133,6 +182,8 @@ static void register_insn_emulation(struct insn_emulation_ops *ops)
         switch (ops->status) {
         case INSN_DEPRECATED:
                 insn->current_mode = INSN_EMULATE;
+                /* Disable the HW mode if it was turned on at early boot time */
+                run_all_cpu_set_hw_mode(insn, false);
                 insn->max = INSN_HW;
                 break;
         case INSN_OBSOLETE:
@@ -453,8 +504,6 @@ ret:
         return 0;
 }
 
-#define SCTLR_EL1_CP15BEN (1 << 5)
-
 static inline void config_sctlr_el1(u32 clear, u32 set)
 {
         u32 val;
@@ -465,48 +514,13 @@ static inline void config_sctlr_el1(u32 clear, u32 set)
         asm volatile("msr sctlr_el1, %0" : : "r" (val));
 }
 
-static void enable_cp15_ben(void *info)
-{
-        config_sctlr_el1(0, SCTLR_EL1_CP15BEN);
-}
-
-static void disable_cp15_ben(void *info)
-{
-        config_sctlr_el1(SCTLR_EL1_CP15BEN, 0);
-}
-
-static int cpu_hotplug_notify(struct notifier_block *b,
-                              unsigned long action, void *hcpu)
-{
-        switch (action) {
-        case CPU_STARTING:
-        case CPU_STARTING_FROZEN:
-                enable_cp15_ben(NULL);
-                return NOTIFY_DONE;
-        case CPU_DYING:
-        case CPU_DYING_FROZEN:
-                disable_cp15_ben(NULL);
-                return NOTIFY_DONE;
-        }
-
-        return NOTIFY_OK;
-}
-
-static struct notifier_block cpu_hotplug_notifier = {
-        .notifier_call = cpu_hotplug_notify,
-};
-
 static int cp15_barrier_set_hw_mode(bool enable)
 {
-        if (enable) {
-                register_cpu_notifier(&cpu_hotplug_notifier);
-                on_each_cpu(enable_cp15_ben, NULL, true);
-        } else {
-                unregister_cpu_notifier(&cpu_hotplug_notifier);
-                on_each_cpu(disable_cp15_ben, NULL, true);
-        }
-
-        return true;
+        if (enable)
+                config_sctlr_el1(0, SCTLR_EL1_CP15BEN);
+        else
+                config_sctlr_el1(SCTLR_EL1_CP15BEN, 0);
+        return 0;
 }
 
 static struct undef_hook cp15_barrier_hooks[] = {
@@ -534,6 +548,20 @@ static struct insn_emulation_ops cp15_barrier_ops = {
         .set_hw_mode = cp15_barrier_set_hw_mode,
 };
 
+static int insn_cpu_hotplug_notify(struct notifier_block *b,
+                              unsigned long action, void *hcpu)
+{
+        int rc = 0;
+        if ((action & ~CPU_TASKS_FROZEN) == CPU_STARTING)
+                rc = run_all_insn_set_hw_mode((unsigned long)hcpu);
+
+        return notifier_from_errno(rc);
+}
+
+static struct notifier_block insn_cpu_hotplug_notifier = {
+        .notifier_call = insn_cpu_hotplug_notify,
+};
+
 /*
  * Invoked as late_initcall, since not needed before init spawned.
  */
@@ -545,6 +573,7 @@ static int __init armv8_deprecated_init(void)
         if (IS_ENABLED(CONFIG_CP15_BARRIER_EMULATION))
                 register_insn_emulation(&cp15_barrier_ops);
 
+        register_cpu_notifier(&insn_cpu_hotplug_notifier);
         register_insn_emulation_sysctl(ctl_abi);
 
         return 0;