Re: firmware selection for SEV-ES

[Laszlo Ersek <lersek@redhat.com>]

On 04/23/21 10:16, Michal Privoznik wrote:
> On 4/22/21 4:13 PM, Laszlo Ersek wrote:
>> On 04/21/21 13:51, Pavel Hrdina wrote:
>>> On Wed, Apr 21, 2021 at 11:54:24AM +0200, Laszlo Ersek wrote:
>>>> Hi Brijesh, Tom,
>>>>
>>>> in QEMU's "docs/interop/firmware.json", the @FirmwareFeature
>>>> enumeration
>>>> has a constant called @amd-sev. We should introduce an @amd-sev-es
>>>> constant as well, minimally for the following reason:
>>>>
>>>> AMD document #56421 ("SEV-ES Guest-Hypervisor Communication Block
>>>> Standardization") revision 1.40 says in "4.6 System Management Mode
>>>> (SMM)" that "SMM will not be supported in this version of the
>>>> specification". This is reflected in OVMF, so an OVMF binary that's
>>>> supposed to run in a SEV-ES guest must be built without "-D
>>>> SMM_REQUIRE". (As a consequence, such a binary should be built also
>>>> without "-D SECURE_BOOT_ENABLE".)
>>>>
>>>> At the level of "docs/interop/firmware.json", this means that
>>>> management
>>>> applications should be enabled to look for the @amd-sev-es feature (and
>>>> it also means, for OS distributors, that any firmware descriptor
>>>> exposing @amd-sev-es will currently have to lack all three of:
>>>> @requires-smm, @secure-boot, @enrolled-keys).
>>>>
>>>> I have three questions:
>>>>
>>>>
>>>> (1) According to
>>>> <https://libvirt.org/formatdomain.html#launch-security>, SEV-ES is
>>>> explicitly requested in the domain XML via setting bit#2 in the
>>>> "policy"
>>>> element.
>>>>
>>>> Can this setting be used by libvirt to look for such a firmware
>>>> descriptor that exposes @amd-sev-es?
>>>
>>> Hi Laszlo and all,
>>>
>>> Currently we use only <launchSecurity type='sev'> when selecting
>>> firmware to make sure that it supports @amd-sev. Since we already have a
>>> place in the VM XML where users can configure amd-sev-as we can use that
>>> information when selecting correct firmware that should be used for the
>>> VM.
>>
>> Thanks!
>>
>> Should we file a libvirtd Feature Request (where?) for recognizing the
>> @amd-sev-es feature flag?
> 
> Yes, we should. We can use RedHat bugzilla for that. Laszlo - do you
> want to do it yourself or shall I help you with that?

Please go ahead, I appreciate your help! :)

Thanks!
Laszlo