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

[Chao Gao]

On Thu, Oct 01, 2026 at 07:54:43AM +0800, Edgecombe, Rick P wrote:
>On Tue, 2026-09-29 at 22:38 -0700, Chao Gao wrote:
>> +	/*
>> +	 * TDX_FIELD_CPUID_CONFIG_LEAVES and TDX_FIELD_CPUID_CONFIG_VALUES
>> +	 * give the field ID of each array's first element. The remaining
>> +	 * elements follow consecutively, in the order they appear in the
>> +	 * structure.
>> +	 */
>> +	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;
>> +
>> +		/* Each config has two u64s of CPUID values. */
>> +		for (j = 0; j < 2; j++) {
>> +			ret = read_sys_metadata_field(
>> +				TDX_FIELD_CPUID_CONFIG_VALUES + i * 2 + j,
>> +				&td_conf->cpuid_config_values[i][j]);
>> +			if (ret)
>> +				return ret;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>
>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?
>

How about:

	/*
	 * 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.
	 */