linux-kernel - Re: [PATCH Part2 v5 17/45] crypto: ccp: Add the SNP_{SET,GET}_EXT

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Message-ID: <922d1ed3-4b51-9cf4-4858-19b16e08badf@amd.com>
Date:   Wed, 1 Sep 2021 18:06:47 -0500
From:   Brijesh Singh <brijesh.singh@....com>
To:     Connor Kuehl <ckuehl@...hat.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Borislav Petkov <bp@...en8.de>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andi Kleen <ak@...ux.intel.com>, tony.luck@...el.com,
        marcorr@...gle.com, sathyanarayanan.kuppuswamy@...ux.intel.com,
        tfanelli@...hat.com
Subject: Re: [PATCH Part2 v5 17/45] crypto: ccp: Add the
 SNP_{SET,GET}_EXT_CONFIG command


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 */
>> +};