[libvirt] [PATCH v1 13/15] qemuDomainDefValidate: Don't require SMM if automatic firmware selection enabled

[Michal Privoznik]

On 2/28/19 12:40 PM, Laszlo Ersek wrote:
> On 02/27/19 11:04, Michal Privoznik wrote:
>> The firmware selection code will enable the feature if needed.
>> There's no need to require SMM to be enabled in that case.
>>
>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> ---
>>   src/qemu/qemu_domain.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
>> index cc3a01397c..b25f26f8b0 100644
>> --- a/src/qemu/qemu_domain.c
>> +++ b/src/qemu/qemu_domain.c
>> @@ -4157,7 +4157,9 @@ qemuDomainDefValidate(const virDomainDef *def,
>>               goto cleanup;
>>           }
>>   
>> -        if (def->features[VIR_DOMAIN_FEATURE_SMM] != VIR_TRISTATE_SWITCH_ON) {
>> +        /* SMM will be enabled by qemuFirmwareFillDomain() if needed. */
>> +        if (def->os.firmware == VIR_DOMAIN_OS_DEF_FIRMWARE_NONE &&
>> +            def->features[VIR_DOMAIN_FEATURE_SMM] != VIR_TRISTATE_SWITCH_ON) {
>>               virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>>                              _("Secure boot requires SMM feature enabled"));
>>               goto cleanup;
>>
> 
> I'm not familiar with the ordering between the code in the previous
> patch and the code in this patch. What is the order? Do we first
> validate and then prepare/fill, or vice versa?

Yeah, I can probably put this one before 11/15 which enables SMM if needed.

> 
> Also, what happens if the domain config explicitly disables SMM
> emulation in <features>, but the firmware requires it? See my point (2)
> in message
> <https://www.redhat.com/archives/libvir-list/2019-February/msg01669.html>.
> Will qemuFirmwareEnableFeatures() simply overwrite the setting? I think
> we should reject the firmware descriptor instead, in
> qemuFirmwareMatchDomain().

Good point. I'll make qemuFirmwareEnableFeatures() fail in that case and 
thus starting the domain will fail. After all, in point (1) you suggest 
that for matching FW @secure == REQUIRES_SMM, therefore transitively if 
@secure='yes' then def->features[SMM] = VIR_TRISTATE_SWITCH_ON. Hence, 
@secure='yes' and SMM='off' is nonsensical combination.

Michal