[RFC PATCH 3/7] conf: introduce TrustDomain element in domain

[Peter Krempa]

On Fri, Jun 18, 2021 at 16:50:48 +0800, Zhenzhong Duan wrote:
> The TrustDomain element can be used to define the security model to
> use when launching a domain. Only type 'tdx' is supported currently.
> 
> When 'tdx' is used, the VM will launched with Intel TDX feature enabled.
> TDX feature supports running encrypted VM (Trust Domain, TD) under the
> control of KVM. A TD runs in a CPU model which protects the
> confidentiality of its memory and its CPU state from other software
> 
> There is a child element 'policy' in TrustDomain. In 'policy', bit 0
> is used to enable TDX debug, other bits are reserved currently.
> 
> For example:
> 
>  <TrustDomain type='tdx'>
>    <policy>0x0001</policy>
>  </TrustDomain>
> 
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan at intel.com>
> ---
>  docs/schemas/domaincommon.rng                 | 16 ++++
>  src/conf/domain_conf.c                        | 84 +++++++++++++++++++
>  src/conf/domain_conf.h                        | 15 ++++
>  src/conf/virconftypes.h                       |  2 +
>  src/qemu/qemu_validate.c                      |  8 ++
>  .../genericxml2xmlindata/trust-domain-tdx.xml | 21 +++++
>  tests/genericxml2xmltest.c                    |  1 +
>  7 files changed, 147 insertions(+)
>  create mode 100644 tests/genericxml2xmlindata/trust-domain-tdx.xml
> 
> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
> index 5ea14b6dbf..2b39a01e84 100644
> --- a/docs/schemas/domaincommon.rng
> +++ b/docs/schemas/domaincommon.rng
> @@ -89,6 +89,9 @@
>          <optional>
>            <ref name="launchSecurity"/>
>          </optional>
> +        <optional>
> +          <ref name="TrustDomain"/>

All our RNG schema entries ...

> +        </optional>
>          <optional>
>            <ref name="bhyvecmdline"/>
>          </optional>
> @@ -518,6 +521,19 @@
>      </element>
>    </define>
>  
> +  <define name="TrustDomain">
> +    <element name="TrustDomain">
> +      <attribute name="type">
> +        <value>tdx</value>
> +      </attribute>
> +      <interleave>
> +        <element name="policy">
> +          <ref name="hexuint"/>
> +        </element>
> +      </interleave>
> +    </element>
> +  </define>
> +
>    <!--
>        Enable or disable perf events for the domain. For each
>        of the events the following rules apply:
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 139cdfc0a7..a51db088c1 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -1403,6 +1403,12 @@ VIR_ENUM_IMPL(virDomainLaunchSecurity,
>                "sev",
>  );
>  
> +VIR_ENUM_IMPL(virDomainTrustDomain,
> +              VIR_DOMAIN_TRUST_DOMAIN_LAST,
> +              "",
> +              "tdx",
> +);
> +
>  static virClass *virDomainObjClass;
>  static virClass *virDomainXMLOptionClass;
>  static void virDomainObjDispose(void *obj);

[...]

> @@ -14793,6 +14810,53 @@ virDomainSEVDefParseXML(xmlNodePtr sevNode,
>      return NULL;
>  }
>  
> +static virDomainTDXDef *
> +virDomainTDXDefParseXML(xmlNodePtr tdxNode,
> +                        xmlXPathContextPtr ctxt)
> +{
> +    VIR_XPATH_NODE_AUTORESTORE(ctxt)
> +    virDomainTDXDef *def;
> +    unsigned long policy;
> +    g_autofree char *type = NULL;
> +
> +    def = g_new0(virDomainTDXDef, 1);
> +
> +    ctxt->node = tdxNode;
> +
> +    if (!(type = virXMLPropString(tdxNode, "type"))) {
> +        virReportError(VIR_ERR_XML_ERROR, "%s",
> +                       _("missing trust domain type"));
> +        goto error;
> +    }
> +
> +    def->sectype = virDomainTrustDomainTypeFromString(type);
> +    switch ((virDomainTrustDomain) def->sectype) {
> +    case VIR_DOMAIN_TRUST_DOMAIN_TDX:
> +        break;
> +    case VIR_DOMAIN_TRUST_DOMAIN_NONE:
> +    case VIR_DOMAIN_TRUST_DOMAIN_LAST:
> +    default:
> +        virReportError(VIR_ERR_XML_ERROR,
> +                       _("unsupported trust domain type '%s'"),
> +                       type);
> +        goto error;
> +    }
> +
> +    if (virXPathULongHex("string(./policy)", ctxt, &policy) < 0) {
> +        virReportError(VIR_ERR_XML_ERROR, "%s",
> +                       _("failed to get trust domain policy"));
> +        goto error;
> +    }
> +
> +    def->policy = policy;
> +
> +    return def;
> +
> + error:
> +    virDomainTDXDefFree(def);

If you register an autoptr cleanup function for this type you'll be able
to avoid the whole 'error' label.

> +    return NULL;
> +}

[...]

> @@ -26870,6 +26941,18 @@ virDomainSEVDefFormat(virBuffer *buf, virDomainSEVDef *sev)
>      virBufferAddLit(buf, "</launchSecurity>\n");
>  }
>  
> +static void
> +virDomainTDXDefFormat(virBuffer *buf, virDomainTDXDef *tdx)
> +{
> +    if (!tdx)
> +        return;
> +
> +    virBufferAsprintf(buf, "<TrustDomain type='tdx'>\n");

... as well as XML element names don't start with capital letter, so
this one shouldn't either.

> +    virBufferAdjustIndent(buf, 2);
> +    virBufferAsprintf(buf, "<policy>0x%04x</policy>\n", tdx->policy);
> +    virBufferAdjustIndent(buf, -2);
> +    virBufferAddLit(buf, "</TrustDomain>\n");
> +}
>  
>  static void

[...]

>  virDomainPerfDefFormat(virBuffer *buf, virDomainPerfDef *perf)
> diff --git a/src/conf/virconftypes.h b/src/conf/virconftypes.h
> index b21068486e..dbd2eb984c 100644
> --- a/src/conf/virconftypes.h
> +++ b/src/conf/virconftypes.h
> @@ -202,6 +202,8 @@ typedef struct _virDomainResourceDef virDomainResourceDef;
>  
>  typedef struct _virDomainSEVDef virDomainSEVDef;
>  
> +typedef struct _virDomainTDXDef virDomainTDXDef;
> +

Plase don't mix generic (conf/) changes ...

>  typedef struct _virDomainShmemDef virDomainShmemDef;
>  
>  typedef struct _virDomainSmartcardDef virDomainSmartcardDef;
> diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
> index 382473d03b..2efd011cc0 100644
> --- a/src/qemu/qemu_validate.c
> +++ b/src/qemu/qemu_validate.c
> @@ -1222,6 +1222,14 @@ qemuValidateDomainDef(const virDomainDef *def,
>          return -1;
>      }
>  
> +    if (def->tdx &&
> +        !virQEMUCapsGet(qemuCaps, QEMU_CAPS_TDX_GUEST)) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("TDX trust domain is not supported with "
> +                         "this QEMU binary"));
> +        return -1;
> +    }

... with targetted qemu changes like this.

> +
>      if (def->naudios > 1 &&
>          !virQEMUCapsGet(qemuCaps, QEMU_CAPS_AUDIODEV)) {
>          virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",

[...]