11:53 a.m.
Secure Encrypted Virtualization (sev) element is used to provide the guest
owners input parameters used for creating an encrypted VM using AMD SEV
feature. SEV feature supports running encrypted VM under the control of
KVM. Encrypted VMs have their pages (code and data) secured such that only
the guest itself has access to the unencrypted version. Each encrypted VM
is associated with a unique encryption key; if its data is accessed to a
different entity using a different key the encrypted guests data will be
incorrectly decrypted, leading to unintelligible data.
QEMU >= 2.12 provides 'sev-guest' object which supports launching encrypted
VMs. A typical command line
# $QEMU ... \
-machine memory-encryption=sev0 \
-object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \
...
Signed-off-by: Brijesh Singh <brijesh.singh(a)amd.com>
---
docs/formatdomain.html.in | 71 +++++++++++++++++++++++++++++++++++++++++++
src/conf/domain_conf.c | 64 +++++++++++++++++++++++++++++++++++++++
src/conf/domain_conf.h | 18 +++++++++++
src/qemu/qemu_command.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 230 insertions(+)
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 6fd2189cd2f4..d18e3fb1d976 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -8195,6 +8195,77 @@ qemu-kvm -net nic,model=? /dev/null
<p>Note: DEA/TDEA is synonymous with DES/TDES.</p>
+ <h3><a id="sev">Secure Encrypted Virtualization
(SEV)</a></h3>
+
+ <p>
+ The contents of the <code>sev</code> element is used to provide the
+ guest owners input used for creating an encrypted VM using the AMD
+ Secure Encrypted Virtualization (SEV) feature.
+
+ SEV is an extension to the AMD-V architecture which supports running
+ encrypted virtual machine (VMs) under the control of KVM. Encrypted
+ VMs have their pages (code and data) secured such that only the guest
+ itself has access to the unencrypted version. Each encrypted VM is
+ associated with a unique encryption key; if its data is accessed to a
+ different entity using a different key the encrypted guests data will
+ be incorrectly decrypted, leading to unintelligible data.
+ </p>
+ <pre>
+<domain>
+ ...
+ <sev>
+ <policy> 1 </policy>
+ <cbitpos> 47 </cbitpos>
+ <reduced-phys-bits> 5 </reduced-phys-bits>
+ <session> ... </session>
+ <dh-cert> ... </dh>
+ </sev>
+ ...
+</domain>
+</pre>
+
+ <p>
+ A least <code>cbitpos</code> and
<code>reduced-phys-bits</code> must be nested
+ within the <code>sev</code> element.
+ </p>
+ <dl>
+ <dt><code>cbitpos</code></dt>
+ <dd>The <code>cbitpos</code> attribute provides the C-bit (aka
encryption bit)
+ location in guest page table entry. The value of <code>cbitpos</code>
is
+ hypervisor dependent and can be obtained through the <code>sev</code>
element
+ from domaincapabilities.
+ </dd>
+ <dt><code>reduced-phys-bits</code></dt>
+ <dd>The <code>reduced-phys-bits</code> attribute provides the
physical
+ address bit reducation. Similar to <code>cbitpos</code> the value of
<code>
+ reduced-phys-bit</code> is hypervisor dependent and can be obtained
+ through the <code>sev</code> element from domaincapabilities.
+ </dd>
+ <dt><code>policy</code></dt>
+ <dd>The <code>policy</code> attribute provides the guest policy
which must
+ be maintained by the SEV firmware. This policy is enforced by the firmware
+ and restricts what configuration and operational commands can be performed
+ on this guest by the hypervisor. The guest policy provided during guest
+ launch is bound to the guest and cannot be changed throughout the lifetime
+ of the guest. The policy is also transmitted during snapshot and migration
+ flows and enforced on the destination platform.
+ </dd>
+ <dt><code>dh-cert</code></dt>
+ <dd>The <code>dh-cert</code> attribute provides the guest owners
public
+ Diffie-Hellman (DH) key. The key is used to negotiate a master secret
+ key between the SEV firmware and guest owner. This master secret key is
+ then used to establish a trusted channel between SEV firmware and guest
+ owner. The value must be encoded in base64.
+ </dd>
+ <dt><code>session</code></dt>
+ <dd>The <code>session</code> attribute provides the guest owners
session
+ blob defined in SEV API spec. The value must be encoded in base64.
+ </dd>
+ </dl>
+
+ <p>Note: More information about <code>policy</code> bit definition,
<code>
+ dh</code> and <code>session</code> is available in SEV API
spec.</p>
+
<h2><a id="examples">Example configs</a></h2>
<p>
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index d96b012b98f0..4c9921b5dca6 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -15539,6 +15539,61 @@ virDomainMemoryTargetDefParseXML(xmlNodePtr node,
return ret;
}
+static void
+virDomainSevDefFree(virDomainSevDefPtr def)
+{
+ VIR_FREE(def->dh_cert);
+ VIR_FREE(def->session);
+
+ VIR_FREE(def);
+}
+
+static virDomainSevDefPtr
+virDomainSevDefParseXML(xmlNodePtr sevNode,
+ xmlXPathContextPtr ctxt)
+{
+ char *tmp = NULL;
+ xmlNodePtr save = ctxt->node;
+ virDomainSevDefPtr def;
+ unsigned long policy;
+
+ ctxt->node = sevNode;
+
+ if (VIR_ALLOC(def) < 0)
+ return NULL;
+
+ if ((tmp = virXPathString("string(./dh-cert)", ctxt))) {
+ if (VIR_STRDUP(def->dh_cert, tmp) < 0)
+ goto error;
+
+ VIR_FREE(tmp);
+ }
+
+ if ((tmp = virXPathString("string(./session)", ctxt))) {
+ if (VIR_STRDUP(def->session, tmp) < 0)
+ goto error;
+
+ VIR_FREE(tmp);
+ }
+
+ if (virXPathULongHex("string(./policy)", ctxt, &policy) == 0) {
+ def->policy = policy;
+ } else {
+ def->policy = -1;
+ }
+
+ virXPathInt("string(./cbitpos)", ctxt, &def->cbitpos);
+ virXPathInt("string(./reduced-phys-bits)", ctxt,
&def->reduced_phys_bits);
+
+ ctxt->node = save;
+ return def;
+
+error:
+ VIR_FREE(tmp);
+ virDomainSevDefFree(def);
+ ctxt->node = save;
+ return NULL;
+}
static virDomainMemoryDefPtr
virDomainMemoryDefParseXML(virDomainXMLOptionPtr xmlopt,
@@ -20212,6 +20267,15 @@ virDomainDefParseXML(xmlDocPtr xml,
ctxt->node = node;
VIR_FREE(nodes);
+ /* Check for SEV feature */
+ if ((n = virXPathNodeSet("./sev", ctxt, &nodes)) < 0)
+ goto error;
+
+ if (n) {
+ def->sev = virDomainSevDefParseXML(nodes[0], ctxt);
+ VIR_FREE(nodes);
+ }
+
/* analysis of memory devices */
if ((n = virXPathNodeSet("./devices/memory", ctxt, &nodes)) < 0)
goto error;
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 368f16f3fbf9..f0f267b28f40 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -142,6 +142,9 @@ typedef virDomainPanicDef *virDomainPanicDefPtr;
typedef struct _virDomainMemoryDef virDomainMemoryDef;
typedef virDomainMemoryDef *virDomainMemoryDefPtr;
+typedef struct _virDomainSevDef virDomainSevDef;
+typedef virDomainSevDef *virDomainSevDefPtr;
+
/* forward declarations virDomainChrSourceDef, required by
* virDomainNetDef
*/
@@ -2289,6 +2292,18 @@ struct _virDomainKeyWrapDef {
int dea; /* enum virTristateSwitch */
};
+typedef struct _virDomainSevDef virDomainSevDef;
+typedef virDomainSevDef *virDomainSevDefPtr;
+
+struct _virDomainSevDef {
+ char *dh_cert;
+ char *session;
+ int policy;
+ int cbitpos;
+ int reduced_phys_bits;
+};
+
+
typedef enum {
VIR_DOMAIN_IOMMU_MODEL_INTEL,
@@ -2454,6 +2469,9 @@ struct _virDomainDef {
virDomainKeyWrapDefPtr keywrap;
+ /* SEV-specific domain */
+ virDomainSevDefPtr sev;
+
/* Application-specific custom metadata */
xmlNodePtr metadata;
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index fa0aa5d5c3d4..653bbe154332 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -9663,6 +9663,80 @@ qemuBuildTPMCommandLine(virCommandPtr cmd,
return 0;
}
+static char *
+qemuBuildSevCreateFile(const virDomainDef *def, const char *name, char *data)
+{
+ char *base = virGetUserConfigDirectory();
+ char *configDir, *configFile;
+ char uuidstr[VIR_UUID_STRING_BUFLEN];
+
+ virUUIDFormat(def->uuid, uuidstr);
+
+ if (virAsprintf(&configDir, "%s/sev/%s", base, uuidstr) < 0)
+ goto error;
+ VIR_FREE(base);
+
+ if (virFileMakePathWithMode(configDir, S_IRWXU) < 0) {
+ virReportSystemError(errno, _("cannot create config directory
'%s'"),
+ configDir);
+ goto error;
+ }
+
+ if (!(configFile = virFileBuildPath(configDir, name, ".base64")))
+ goto error;
+
+ if (virFileRewriteStr(configFile, S_IRUSR | S_IWUSR, data) < 0) {
+ virReportSystemError(errno, _("failed to write data to config
'%s'"),
+ configFile);
+ goto error;
+ }
+
+ return configFile;
+
+error:
+ return NULL;
+}
+
+static int
+qemuBuildSevCommandLine(virCommandPtr cmd,
+ const virDomainDef *def)
+{
+ virDomainSevDefPtr sev = def->sev;
+ virBuffer buf = VIR_BUFFER_INITIALIZER;
+ virBuffer obj = VIR_BUFFER_INITIALIZER;
+ char *dh_cert_file = NULL;
+ char *session_file = NULL;
+
+ /* qemu accepts DH and session blob as file, create a temporary file */
+ if (sev->dh_cert &&
+ !(dh_cert_file = qemuBuildSevCreateFile(def, "dh_cert",
sev->dh_cert)))
+ return -1;
+
+ if (sev->session &&
+ !(session_file = qemuBuildSevCreateFile(def, "session",
sev->session)))
+ return -1;
+
+ virCommandAddArg(cmd, "-machine");
+ virBufferAddLit(&buf, "memory-encryption=sev0");
+ virCommandAddArgBuffer(cmd, &buf);
+
+ virCommandAddArg(cmd, "-object");
+ virBufferAddLit(&obj, "sev-guest,id=sev0");
+ if (sev->policy > 0)
+ virBufferAsprintf(&obj, ",policy=0x%x", sev->policy);
+ virBufferAsprintf(&obj, ",cbitpos=%d", sev->cbitpos);
+ virBufferAsprintf(&obj, ",reduced-phys-bits=%d",
sev->reduced_phys_bits);
+ if (dh_cert_file)
+ virBufferAsprintf(&obj, ",dh-cert-file=%s", dh_cert_file);
+ if (session_file)
+ virBufferAsprintf(&obj, ",session-file=%s", session_file);
+ virCommandAddArgBuffer(cmd, &obj);
+
+ VIR_DEBUG("policy=0x%x cbitpos=%d reduced_phys_bits=%d dh=%s session=%s",
+ sev->policy, sev->cbitpos, sev->reduced_phys_bits, dh_cert_file,
+ session_file);
+ return 0;
+}
static int
qemuBuildVMCoreInfoCommandLine(virCommandPtr cmd,
@@ -10108,6 +10182,9 @@ qemuBuildCommandLine(virQEMUDriverPtr driver,
if (qemuBuildVMCoreInfoCommandLine(cmd, def, qemuCaps) < 0)
goto error;
+ if (def->sev && qemuBuildSevCommandLine(cmd, def) < 0)
+ goto error;
+
if (snapshot)
virCommandAddArgList(cmd, "-loadvm", snapshot->def->name, NULL);
--
2.14.3