Re: [PATCH v3 07/10] x86/virt/tdx: Convert the td_conf metadata reader

[Chao Gao]

On Fri, Oct 02, 2026 at 04:28:54AM +0800, Edgecombe, Rick P wrote:
>On Thu, 2026-10-01 at 19:34 +0300, Nikolay Borisov wrote:
>> > The comments are not strictly required, but probably fit into turning this
>> > thing
>> > into "hand coding". I think it's a nice addition. I wonder if we should make
>> > the
>> > "i * 2 + j" a bit clearer though?
>> > 
>> > I'm not against leaving it as is for now. It helps that it doesn't morph too
>> > much from the code getting moved. But I think the above falls a bit short of
>> > hand coded quality.
>> 
>> Perhaps this code warrants open coding? The code will end up looking 
>> like config_values[i][0] ... config_values[i][1] ....
>
>Yea that would be a good way to improve it.

Yes. With one less level of indentation, all three reads get the same
shape. I ended up with:

	/*
	 * cpuid_config_leaves[i] holds a CPUID leaf and sub-leaf number,
	 * and the two u64s of cpuid_config_values[i] mark which bits of
	 * that leaf's EAX/EBX/ECX/EDX the host can set to 0 or 1 for a TD.
	 *
	 * TDX_FIELD_CPUID_CONFIG_LEAVES and TDX_FIELD_CPUID_CONFIG_VALUES
	 * give the field ID of each array's first element, and the rest
	 * follow in order.
	 */
	for (i = 0; i < td_conf->num_cpuid_config; i++) {
		ret = read_sys_metadata_field(TDX_FIELD_CPUID_CONFIG_LEAVES + i,
					      &td_conf->cpuid_config_leaves[i]);
		if (ret)
			return ret;

		ret = read_sys_metadata_field(TDX_FIELD_CPUID_CONFIG_VALUES + i * 2,
					      &td_conf->cpuid_config_values[i][0]);
		if (ret)
			return ret;

		ret = read_sys_metadata_field(TDX_FIELD_CPUID_CONFIG_VALUES + i * 2 + 1,
					      &td_conf->cpuid_config_values[i][1]);
		if (ret)
			return ret;
	}