Re: [PATCH v11 1/3] x86/tdx: Add TDX Guest attestation interface driver

[Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>]

On 8/29/22 1:28 PM, Dave Hansen wrote:
> On 8/29/22 13:09, Sathyanarayanan Kuppuswamy wrote:
>> With the changed format, we avoided the holes, but it still adds 7 bytes of padding.
>>
>> Total size of struct is 32 bytes.
>>
>> struct tdx_report_req {
>> 	__u64                      reportdata;           /*     0     8 */
>> 	__u64                      tdreport;             /*     8     8 */
>> 	__u32                      rpd_len;              /*    16     4 */
>> 	__u32                      tdr_len;              /*    20     4 */
>> 	__u8                       subtype;              /*    24     1 */
>>
>> 	/* size: 32, cachelines: 1, members: 5 */
>> 	/* padding: 7 */
>> 	/* last cacheline: 32 bytes */
>> };
> 
> Might as well make some use of the padding and add:
> 
> 	u8 reserved[7];
> 
> That will ensure that the entire structure is explicitly sized *AND*
> leave you room to add flags or other fun in the future without a new ABI.

Ok. I will add it in next version.

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer