[libvirt] [PATCH v5 05/10] qemu: add support to launch SEV guest

[Brijesh Singh]

QEMU >= 2.12 provides 'sev-guest' object which is used to launch encrypted
VMs on AMD platform using SEV feature. The various inputs required to
launch SEV guest is provided through the <launch-security> tag. A typical
SEV guest launch command line looks like this:

# $QEMU ...\
  -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 ...\
  -machine memory-encryption=sev0 \

Signed-off-by: Brijesh Singh <brijesh.singh at amd.com>
---
 src/qemu/qemu_command.c | 35 +++++++++++++++++++++++++++++
 src/qemu/qemu_process.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 93 insertions(+)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 682d714..55bbfa2 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -7405,6 +7405,9 @@ qemuBuildMachineCommandLine(virCommandPtr cmd,
             virQEMUCapsGet(qemuCaps, QEMU_CAPS_LOADPARM))
             qemuAppendLoadparmMachineParm(&buf, def);
 
+        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_SEV_GUEST) && def->sev)
+            virBufferAddLit(&buf, ",memory-encryption=sev0");
+
         virCommandAddArgBuffer(cmd, &buf);
     }
 
@@ -9750,6 +9753,35 @@ qemuBuildTPMCommandLine(virCommandPtr cmd,
     return 0;
 }
 
+static void
+qemuBuildSevCommandLine(virDomainObjPtr vm, virCommandPtr cmd,
+                        virDomainSevDefPtr sev)
+{
+    virBuffer obj = VIR_BUFFER_INITIALIZER;
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    char *path = NULL;
+
+    VIR_DEBUG("policy=0x%x cbitpos=%d reduced_phys_bits=%d",
+              sev->policy, sev->cbitpos, sev->reduced_phys_bits);
+
+    virBufferAsprintf(&obj, "sev-guest,id=sev0,cbitpos=%d", sev->cbitpos);
+    virBufferAsprintf(&obj, ",reduced-phys-bits=%d", sev->reduced_phys_bits);
+    virBufferAsprintf(&obj, ",policy=0x%x", sev->policy);
+
+    if (sev->dh_cert) {
+        ignore_value(virAsprintf(&path, "%s/dh_cert.base64", priv->libDir));
+        virBufferAsprintf(&obj, ",dh-cert-file=%s", path);
+        VIR_FREE(path);
+    }
+
+    if (sev->session) {
+        ignore_value(virAsprintf(&path, "%s/session.base64", priv->libDir));
+        virBufferAsprintf(&obj, ",session-file=%s", path);
+        VIR_FREE(path);
+    }
+
+    virCommandAddArgList(cmd, "-object", virBufferContentAndReset(&obj), NULL);
+}
 
 static int
 qemuBuildVMCoreInfoCommandLine(virCommandPtr cmd,
@@ -10195,6 +10227,9 @@ qemuBuildCommandLine(virQEMUDriverPtr driver,
     if (qemuBuildVMCoreInfoCommandLine(cmd, def, qemuCaps) < 0)
         goto error;
 
+    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_SEV_GUEST) && def->sev)
+        qemuBuildSevCommandLine(vm, cmd, def->sev);
+
     if (snapshot)
         virCommandAddArgList(cmd, "-loadvm", snapshot->def->name, NULL);
 
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index c0105c8..0c93f15 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -5745,6 +5745,61 @@ qemuProcessPrepareDomain(virQEMUDriverPtr driver,
     return ret;
 }
 
+static int
+qemuBuildSevCreateFile(const char *configDir, const char *name,
+                       const char *data)
+{
+    char *configFile;
+
+    if (!(configFile = virFileBuildPath(configDir, name, ".base64")))
+        return -1;
+
+    if (virFileRewriteStr(configFile, S_IRUSR | S_IWUSR, data) < 0) {
+        virReportSystemError(errno, _("failed to write data to config '%s'"),
+                             configFile);
+        goto error;
+    }
+
+    VIR_FREE(configFile);
+    return 0;
+
+ error:
+    VIR_FREE(configFile);
+    return -1;
+}
+
+static int
+qemuProcessPrepareSevGuestInput(virDomainObjPtr vm)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    virDomainDefPtr def = vm->def;
+    virQEMUCapsPtr qemuCaps = priv->qemuCaps;
+    virDomainSevDefPtr sev = def->sev;
+
+    if (!sev)
+        return 0;
+
+    VIR_DEBUG("Prepare SEV guest");
+
+    if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_SEV_GUEST)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                        _("Domain %s asked for 'sev' launch but "
+                          "QEMU does not support SEV feature"), vm->def->name);
+        return -1;
+    }
+
+    if (sev->dh_cert) {
+        if (qemuBuildSevCreateFile(priv->libDir, "dh_cert", sev->dh_cert) < 0)
+            return -1;
+    }
+
+    if (sev->session) {
+        if (qemuBuildSevCreateFile(priv->libDir, "session", sev->session) < 0)
+            return -1;
+    }
+
+    return 0;
+}
 
 static int
 qemuProcessPrepareHostStorage(virQEMUDriverPtr driver,
@@ -5870,6 +5925,9 @@ qemuProcessPrepareHost(virQEMUDriverPtr driver,
     if (qemuProcessPrepareHostStorage(driver, vm, flags) < 0)
         goto cleanup;
 
+    if (qemuProcessPrepareSevGuestInput(vm) < 0)
+        goto cleanup;
+
     ret = 0;
  cleanup:
     virObjectUnref(cfg);
-- 
2.7.4