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

[Binbin Wu]

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();
> +	}