[PATCH 2/3] arm64: Consolidate hotplug notifier for instruction emulation

Hi Suzuki,

A possible simplification below.

"Suzuki K. Poulose" [off-list ref] writes:

From: "Suzuki K. Poulose" <suzuki.poulose@arm.com>

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 <redacted>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Punit Agrawal <redacted>
---
 arch/arm64/include/asm/cputype.h     |    2 +
 arch/arm64/kernel/armv8_deprecated.c |  125 +++++++++++++++++++++-------------
 2 files changed, 79 insertions(+), 48 deletions(-)

[...]

You can simplify (drop?) this...

+		insn->ops->set_hw_mode(true);
+}
+
+static void disable_insn_hw_mode(void *data)
+{
+	struct insn_emulation *insn = (struct insn_emulation *)data;
+	if (insn && insn->ops->set_hw_mode)

and this check since...

+		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;

insn->ops->set_hw_mode is already checked here.

+	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(enable, "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)
 {

[...]