On Mon, Nov 15, 2021 at 02:38:04PM -0500, Tyler Fanelli wrote:
> Probe for SEV-ES and SEV-SNP capabilities to distinguish between Rome,
> Naples, and Milan processors. Use the CPUID function to probe if a
> processor is capable of running SEV-ES or SEV-SNP, rather than if it
> actually is running SEV-ES or SEV-SNP.
>
> Signed-off-by: Tyler Fanelli <tfane...@redhat.com>
> ---
> qapi/misc-target.json | 11 +++++++++--
> target/i386/sev.c | 6 ++++--
> 2 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/qapi/misc-target.json b/qapi/misc-target.json
> index 5aa2b95b7d..c3e9bce12b 100644
> --- a/qapi/misc-target.json
> +++ b/qapi/misc-target.json
> @@ -182,13 +182,19 @@
> # @reduced-phys-bits: Number of physical Address bit reduction when SEV is
> # enabled
> #
> +# @es: SEV-ES capability of the machine.
> +#
> +# @snp: SEV-SNP capability of the machine.
> +#
> # Since: 2.12
> ##
> { 'struct': 'SevCapability',
> 'data': { 'pdh': 'str',
> 'cert-chain': 'str',
> 'cbitpos': 'int',
> - 'reduced-phys-bits': 'int'},
> + 'reduced-phys-bits': 'int',
> + 'es': 'bool',
> + 'snp': 'bool'},
> 'if': 'TARGET_I386' }
>
> ##
> @@ -205,7 +211,8 @@
> #
> # -> { "execute": "query-sev-capabilities" }
> # <- { "return": { "pdh": "8CCDD8DDD", "cert-chain": "888CCCDDDEE",
> -# "cbitpos": 47, "reduced-phys-bits": 5}}
> +# "cbitpos": 47, "reduced-phys-bits": 5
> +# "es": false, "snp": false}}
We've previously had patches posted to support SNP in QEMU
https://lists.gnu.org/archive/html/qemu-devel/2021-08/msg04761.html
and this included an update to query-sev for reporting info
about the VM instance.
Your patch is updating query-sev-capabilities, which is a
counterpart for detecting host capabilities separate from
a guest instance.
None the less I wonder if the same design questions from
query-sev apply. ie do we need to have the ability to
report any SNP specific information fields, if so we need
to use a discriminated union of structs, not just bool
flags.
More generally I'm some what wary of adding this to
query-sev-capabilities at all, unless it is part of the
main SEV-SNP series.
Also what's the intended usage for the mgmt app from just
having these boolean fields ? Are they other more explicit
feature flags we should be reporting, instead of what are
essentially SEV generation codenames.
Regards,
Daniel
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