Re: [PATCH v3 1/2] tpm: Use new ptm_cap_n structure for PTM_GET_CAPABILITY

[Stefan Berger <stefanb@linux.ibm.com>]

On 10/16/24 11:03 AM, Daniel P. Berrangé wrote:
> On Wed, Oct 16, 2024 at 10:57:07AM -0400, Stefan Berger wrote:
>> Use the new ptm_cap_n structure for getting the PTM_GET_CAPABILITY response
>> from swtpm. Previously only 17 bits could possibly have been set in ptm_cap
>> (=uint64_t) in big endian order and those bits are now found in the 2nd
>> 32bit word in the response in the caps field.
>>
>> This data structure makes it now clear that the 1st 32bit word carries the
>> tpm_result like all the other response structures of all other commands
>> do.
>>
>> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
>> ---
>>   backends/tpm/tpm_emulator.c | 14 ++++++++------
>>   backends/tpm/tpm_ioctl.h    | 13 ++++++++++++-
>>   backends/tpm/trace-events   |  2 +-
>>   3 files changed, 21 insertions(+), 8 deletions(-)
>>
> 
>> diff --git a/backends/tpm/tpm_ioctl.h b/backends/tpm/tpm_ioctl.h
>> index 1933ab6855..ee2dd15d35 100644
>> --- a/backends/tpm/tpm_ioctl.h
>> +++ b/backends/tpm/tpm_ioctl.h
>> @@ -29,6 +29,16 @@
>>   
>>   typedef uint32_t ptm_res;
>>   
>> +/* PTM_GET_CAPABILITY: Get supported capabilities (ioctl's) */
>> +struct ptm_cap_n {
>> +    union {
>> +        struct {
>> +            ptm_res tpm_result; /* will always be TPM_SUCCESS (0) */
>> +            uint32_t caps;
>> +        } resp; /* response */
>> +    } u;
>> +};
> 
> The union here is pointless surely, since it only has one entry and
> the following patch doesn't add a 2nd either ?

I did this because all commands have a union.
> 
> 
> With regards,
> Daniel