Re: [PATCH v2 4/5] x86/virt/tdx: Add extra memory to TDX module for the extensions

[Chao Gao <chao.gao@intel.com>]

>+static __init int tdx_ext_mem_setup(void)
>+{
>+	unsigned int required_pages = tdx_sysinfo.ext.memory_pool_required_pages;
>+	struct tdx_hpa_list *hpa_list;
>+	unsigned int added_pages;
>+	struct page *page;
>+	int ret;
>+
>+	/*
>+	 * TDX module uses the metadata memory_pool_required_pages to indicate
>+	 * how much memory is still needed. This value decreases each time
>+	 * memory is added via TDH.EXT.MEM.ADD.
>+	 *
>+	 * On first time initialization, a value of 0 before any memory is
>+	 * added is unusual. But host makes no assumptions. Skip the memory
>+	 * setup and let subsequent steps catch any actual errors.
>+	 */

The fact that the value decreases on each TDH.EXT.MEM.ADD is not relevant
here.

Also, calling 0 "unusual" does not help the reader. It is either a valid
value the kernel needs to handle, or an invalid one the kernel can assert
on.

How about:
	
	/*
	 * The TDX module may require no memory at all. Skip the memory
	 * setup in that case.
	 */

>+	if (!required_pages)
>+		return 0;