Re: [PATCH] target/i386/sev: add the support to query the attestation report

[Eric Blake]

On 12/4/20 3:31 PM, Brijesh Singh wrote:
> The SEV FW >= 0.23 added a new command that can be used to query the
> attestation report containing the SHA-256 digest of the guest memory
> and VMSA encrypted with the LAUNCH_UPDATE and sign it with the PEK.
> 
> Note, we already have a command (LAUNCH_MEASURE) that can be used to
> query the SHA-256 digest of the guest memory encrypted through the
> LAUNCH_UPDATE. The main difference between previous and this command
> is that the report is signed with the PEK and unlike the LAUNCH_MEASURE
> command the ATTESATION_REPORT command can be called while the guest
> is running.
> 
> Add a QMP interface "query-sev-attestation-report" that can be used
> to get the report encoded in base64.
> 

> +++ b/qapi/misc-target.json
> @@ -267,3 +267,41 @@
>  ##
>  { 'command': 'query-gic-capabilities', 'returns': ['GICCapability'],
>    'if': 'defined(TARGET_ARM)' }
> +
> +
> +##
> +# @SevAttestationReport:
> +#
> +# The struct describes attestation report for a Secure Encrypted 
> Virtualization
> +# feature.
> +#
> +# @data:  guest attestation report (base64 encoded)
> +#
> +#
> +# Since: 5.2

You've missed the 5.2 release; this should be since 6.0.

> +##
> +{ 'struct': 'SevAttestationReport',
> +  'data': { 'data': 'str'},
> +  'if': 'defined(TARGET_I386)' }
> +
> +##
> +# @query-sev-attestation-report:
> +#
> +# This command is used to get the SEV attestation report, and is supported 
> on AMD
> +# X86 platforms only.
> +#
> +# @mnonce: a random 16 bytes of data (it will be included in report)

This says 16 bytes,...

> +#
> +# Returns: SevAttestationReport objects.
> +#
> +# Since: 5.2

Likewise.

> +#
> +# Example:
> +#
> +# -> { "execute" : "query-sev-attestation-report", "arguments": { "mnonce": 
> "aaaaaaa" } }

...but this example does not use 16 bytes.  That's confusing.

> +# <- { "return" : { "data": "aaaaaaaabbbddddd"} }
> +#
> +##
> +{ 'command': 'query-sev-attestation-report', 'data': { 'mnonce': 'str' },
> +  'returns': 'SevAttestationReport',
> +  'if': 'defined(TARGET_I386)' }
> diff --git a/target/i386/monitor.c b/target/i386/monitor.c


-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org