Re: [PATCH Part2 v5 17/45] crypto: ccp: Add the SNP_{SET,GET}_EXT_CONFIG command

Brijesh Singh
2021-09-01T23:06:54Z

On 9/1/21 4:02 PM, Connor Kuehl wrote:
> On 8/20/21 10:58 AM, Brijesh Singh wrote:
>> +2.4 SNP_SET_EXT_CONFIG
>> +----------------------
>> +:Technology: sev-snp
>> +:Type: hypervisor ioctl cmd
>> +:Parameters (in): struct sev_data_snp_ext_config
>> +:Returns (out): 0 on success, -negative on error
>> +
>> +The SNP_SET_EXT_CONFIG is used to set the system-wide configuration such as
>> +reported TCB version in the attestation report. The command is similar to
>> +SNP_CONFIG command defined in the SEV-SNP spec. The main difference is the
>> +command also accepts an additional certificate blob defined in the GHCB
>> +specification.
>> +
>> +If the certs_address is zero, then previous certificate blob will deleted.
>> +For more information on the certificate blob layout, see the GHCB spec
>> +(extended guest request message).
> Hi Brijesh,
>
> Just to be clear, is the documentation you're referring to regarding the
> layout of the certificate blob specified on page 47 of the GHCB spec?
> More specifically, is it the `struct cert_table` on that page?

Yes that is correct.

>
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdeveloper.amd.com%2Fwp-content%2Fresources%2F56421.pdf&amp;data=04%7C01%7Cbrijesh.singh%40amd.com%7C62df2fe1cb384de88ed708d96d8bda20%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637661270135555480%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=V4S8atM%2BTlZ%2BiIlddRjpTNIx4yecGEoETuFVjeNWWNQ%3D&amp;reserved=0
>
> If so, where is the VCEK certificate layout documented?

You can get the VCEK from the KDS using the chip id. The certificate is
standard X.509.

thanks

>
> Connor
>
>> +/**
>> + * struct sev_data_snp_ext_config - system wide configuration value for SNP.
>> + *
>> + * @config_address: address of the struct sev_user_data_snp_config or 0 when
>> + * reported_tcb does not need to be updated.
>> + * @certs_address: address of extended guest request certificate chain or
>> + * 0 when previous certificate should be removed on SNP_SET_EXT_CONFIG.
>> + * @certs_len: length of the certs
>> + */
>> +struct sev_user_data_ext_snp_config {
>> + __u64 config_address; /* In */
>> + __u64 certs_address; /* In */
>> + __u32 certs_len; /* In */
>> +};