[libvirt] [PATCH v2 4/9] 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 | 33 ++++++++++++++++++
 src/qemu/qemu_process.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 124 insertions(+)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index fa0aa5d5c3d4..39f136a389cb 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -9663,6 +9663,36 @@ qemuBuildTPMCommandLine(virCommandPtr cmd,
     return 0;
 }
 
+static void
+qemuBuildSevCommandLine(virCommandPtr cmd,
+                        virDomainSevDefPtr sev)
+{
+    virBuffer obj = VIR_BUFFER_INITIALIZER;
+    char *path = NULL;
+
+    VIR_DEBUG("policy=0x%x cbitpos=%d reduced_phys_bits=%d",
+              sev->policy, sev->cbitpos, sev->reduced_phys_bits);
+
+    virCommandAddArgList(cmd, "-machine", "memory-encryption=sev0", NULL);
+
+    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", sev->configDir));
+        virBufferAsprintf(&obj, ",dh-cert-file=%s", path);
+        VIR_FREE(path);
+    }
+
+    if (sev->session) {
+        ignore_value(virAsprintf(&path, "%s/session.base64", sev->configDir));
+        virBufferAsprintf(&obj, ",session-file=%s", path);
+        VIR_FREE(path);
+    }
+
+    virCommandAddArgList(cmd, "-object", virBufferContentAndReset(&obj), NULL);
+}
 
 static int
 qemuBuildVMCoreInfoCommandLine(virCommandPtr cmd,
@@ -10108,6 +10138,9 @@ qemuBuildCommandLine(virQEMUDriverPtr driver,
     if (qemuBuildVMCoreInfoCommandLine(cmd, def, qemuCaps) < 0)
         goto error;
 
+    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_SEV) && def->sev)
+        qemuBuildSevCommandLine(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 57c06c7c1550..349e12b6dc12 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -3457,6 +3457,16 @@ qemuProcessBuildDestroyMemoryPathsImpl(virQEMUDriverPtr driver,
 }
 
 
+static void
+qemuProcessDestroySevPaths(virDomainSevDefPtr sev)
+{
+    if (!sev)
+        return;
+
+    virFileDeleteTree(sev->configDir);
+    VIR_FREE(sev->configDir);
+}
+
 int
 qemuProcessBuildDestroyMemoryPaths(virQEMUDriverPtr driver,
                                    virDomainObjPtr vm,
@@ -5741,6 +5751,83 @@ 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(virQEMUDriverPtr driver,
+                                virDomainObjPtr vm)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    virDomainDefPtr def = vm->def;
+    virQEMUCapsPtr qemuCaps = priv->qemuCaps;
+    virDomainSevDefPtr sev = def->sev;
+    char *configDir = NULL;
+    char *domPath = virDomainDefGetShortName(def);
+    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+
+    if (!sev)
+        return 0;
+
+    VIR_DEBUG("Prepare SEV guest");
+
+    if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_SEV)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                        _("Domain %s asked for 'sev' launch but "
+                          "QEMU does not support SEV feature"), vm->def->name);
+        return -1;
+    }
+
+    if (virAsprintf(&configDir, "%s/sev/%s", cfg->configDir, domPath) < 0)
+        goto error;
+
+    if (virFileMakePathWithMode(configDir, S_IRWXU) < 0) {
+        virReportSystemError(errno, _("cannot create config directory '%s'"),
+                             configDir);
+        goto error;
+    }
+
+    if (sev->dh_cert) {
+        if (qemuBuildSevCreateFile(configDir, "dh_cert", sev->dh_cert) < 0)
+            goto error1;
+    }
+
+    if (sev->session) {
+        if (qemuBuildSevCreateFile(configDir, "session", sev->session) < 0)
+            goto error1;
+    }
+
+    VIR_FREE(domPath);
+    sev->configDir = configDir;
+    return 0;
+
+ error1:
+    virFileDeleteTree(configDir);
+ error:
+    VIR_FREE(configDir);
+    VIR_FREE(domPath);
+    return -1;
+}
 
 static int
 qemuProcessPrepareHostStorage(virQEMUDriverPtr driver,
@@ -5866,6 +5953,9 @@ qemuProcessPrepareHost(virQEMUDriverPtr driver,
     if (qemuProcessPrepareHostStorage(driver, vm, flags) < 0)
         goto cleanup;
 
+    if (qemuProcessPrepareSevGuestInput(driver, vm) < 0)
+        goto cleanup;
+
     ret = 0;
  cleanup:
     virObjectUnref(cfg);
@@ -6535,6 +6625,7 @@ void qemuProcessStop(virQEMUDriverPtr driver,
     }
 
     qemuProcessBuildDestroyMemoryPaths(driver, vm, NULL, false);
+    qemuProcessDestroySevPaths(vm->def->sev);
 
     vm->def->id = -1;
 
-- 
2.14.3