Re: [PATCH v5 02/22] cc_platform: Add new attribute to prevent ACPI CPU hotplug

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On 2022/6/22 19:15, Kai Huang wrote:
@@ -357,6 +358,17 @@ static int acpi_processor_add(struct acpi_device *device,
  	struct device *dev;
  	int result = 0;
+ /*
+	 * If the confidential computing platform doesn't support ACPI
+	 * memory hotplug, the BIOS should never deliver such event to
memory or cpu hotplug?


+	 * the kernel.  Report ACPI CPU hot-add as a BIOS bug and ignore
+	 * the new CPU.
+	 */
+	if (cc_platform_has(CC_ATTR_ACPI_CPU_HOTPLUG_DISABLED)) {
+		dev_err(&device->dev, "[BIOS bug]: Platform doesn't support ACPI CPU hotplug.  New CPU ignored.\n");
+		return -EINVAL;
+	}
+
  	pr = kzalloc(sizeof(struct acpi_processor), GFP_KERNEL);
  	if (!pr)
  		return -ENOMEM;
@@ -434,6 +446,17 @@ static void acpi_processor_remove(struct acpi_device *device)
  	if (!device || !acpi_driver_data(device))
  		return;
+ /*
+	 * The confidential computing platform is broken if ACPI memory
ditto


+	 * hot-removal isn't supported but it happened anyway.  Assume
+	 * it's not guaranteed that the kernel can continue to work
+	 * normally.  Just BUG().
+	 */
+	if (cc_platform_has(CC_ATTR_ACPI_CPU_HOTPLUG_DISABLED)) {
+		dev_err(&device->dev, "Platform doesn't support ACPI CPU hotplug. BUG().\n");
+		BUG();
+	}




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