[libvirt PATCH 1/5] qemu_capabilities: detect if confidential-guest-support is available

[Peter Krempa]

On Fri, Jun 11, 2021 at 15:24:09 +0200, Pavel Hrdina wrote:
> In libvirt we already use `query-command-line-options` QMP command but
> that is useless as it doesn't provide correct data for `-machine`
> option. So we need a new and better way to get that data.
> 
> We already use `qom-list-properties` to get options for specific machine
> types so we can reuse it to get options for special `none` machine type
> as a generic arch independent machine type.
> 
> Signed-off-by: Pavel Hrdina <phrdina at redhat.com>


[...]

> 
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 2b9ab9af60..436fe40f65 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -632,6 +632,9 @@ VIR_ENUM_IMPL(virQEMUCaps,
>                "input-linux",
>                "virtio-gpu-gl-pci",
>                "virtio-vga-gl",
> +
> +              /* 405 */
> +              "confidential-guest-support",
>      );
>  
>  
> @@ -1756,6 +1759,10 @@ static struct virQEMUCapsStringFlags virQEMUCapsMachinePropsVirt[] = {
>      { "iommu", QEMU_CAPS_MACHINE_VIRT_IOMMU },
>  };
>  
> +static struct virQEMUCapsStringFlags virQEMUCapsMachinePropsGeneric[] = {
> +    { "confidential-guest-support", QEMU_CAPS_MACHINE_CONFIDENTAL_GUEST_SUPPORT },

If possible please include this line and all the detection that happens
from it in a separate commit including the definition of the new
capability flag.

> +};
> +
>  static virQEMUCapsObjectTypeProps virQEMUCapsMachineProps[] = {
>      { "pseries", virQEMUCapsMachinePropsPSeries,
>        G_N_ELEMENTS(virQEMUCapsMachinePropsPSeries),
> @@ -1763,6 +1770,9 @@ static virQEMUCapsObjectTypeProps virQEMUCapsMachineProps[] = {
>      { "virt", virQEMUCapsMachinePropsVirt,
>        G_N_ELEMENTS(virQEMUCapsMachinePropsVirt),
>        -1 },
> +    { "none", virQEMUCapsMachinePropsGeneric,
> +      G_N_ELEMENTS(virQEMUCapsMachinePropsGeneric),
> +      -1 },
>  };
>  
>  static void
> @@ -2865,8 +2875,10 @@ virQEMUCapsProbeQMPMachineProps(virQEMUCaps *qemuCaps,
>          const char *canon = virQEMUCapsGetCanonicalMachine(qemuCaps, virtType, props.type);
>          g_autofree char *type = NULL;
>  
> -        if (!virQEMUCapsIsMachineSupported(qemuCaps, virtType, canon))
> +        if (STRNEQ(canon, "none") &&
> +            !virQEMUCapsIsMachineSupported(qemuCaps, virtType, canon)) {
>              continue;

This looks fishy since after this patch we'll ever only skip the 'none'
machine, whereas previously we'd let get virQEMUCapsIsMachineSupported
called.

> +        }
>  
>          /* The QOM type for machine types is the machine type name
>           * followed by the -machine suffix */
> diff --git a/tests/qemucapabilitiesdata/caps_2.12.0.aarch64.replies b/tests/qemucapabilitiesdata/caps_2.12.0.aarch64.replies
> index 884db53152..aa8209cc42 100644
> --- a/tests/qemucapabilitiesdata/caps_2.12.0.aarch64.replies
> +++ b/tests/qemucapabilitiesdata/caps_2.12.0.aarch64.replies
> @@ -17523,9 +17523,122 @@
>    "id": "libvirt-36"
>  }
>  
> +{
> +  "execute": "qom-list-properties",
> +  "arguments": {
> +    "typename": "none-machine"
> +  },
> +  "id": "libvirt-37"
> +}

As noted above, I'd prefer if the update of replies is separated from
addition of the capability.