[PATCH v2 4/9] qemu: tpm: Pass --migration option to swtpm if supported

[Stefan Berger <stefanb@xxxxxxxxxxxxx>]

Always pass the --migration option to swtpm, if swptm supports it (staring
with v0.8). Always apply the 'release-lock-outgoing' parameter with this
option and apply the 'incoming' parameter for incoming migration so that
swtpm releases the file lock on the source side when the state is migrated
and locks the file on the destination side when the state is received.

If a started swtpm instance is capable of migrating with share storage
then remember this with a flag in the virDomainTPMDef. This flag allows
for modifications of the installed swtpm, such as installing a version
that does not support migration with shared storage.

Report an error if swtpm does not support the --migration option and an
incoming migration across shared storage is requested.

Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
---
 src/conf/domain_conf.h    |  1 +
 src/qemu/qemu_migration.c |  8 ++++++++
 src/qemu/qemu_tpm.c       | 40 +++++++++++++++++++++++++++++++++++++++
 src/qemu/qemu_tpm.h       |  3 +++
 4 files changed, 52 insertions(+)

diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 352b88eae5..4f9b5c6686 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -1461,6 +1461,7 @@ struct _virDomainTPMDef {
             bool hassecretuuid;
             bool persistent_state;
             virBitmap *activePcrBanks;
+            bool canMigrateWithSharedStorage;
         } emulator;
     } data;
 };
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index efb27a24aa..431b1b0bcb 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -38,6 +38,7 @@
 #include "qemu_security.h"
 #include "qemu_slirp.h"
 #include "qemu_block.h"
+#include "qemu_tpm.h"
 
 #include "domain_audit.h"
 #include "virlog.h"
@@ -2789,6 +2790,13 @@ qemuMigrationSrcBegin(virConnectPtr conn,
         goto cleanup;
     }
 
+    if ((flags & VIR_MIGRATE_TPM_SHARED_STORAGE) &&
+        !qemuTPMCanMigrateSharedStorage(vm->def)) {
+        virReportError(VIR_ERR_NO_SUPPORT, "%s",
+                       _("the running swtpm does not support migration with shared storage"));
+        goto cleanup;
+    }
+
     if (flags & VIR_MIGRATE_POSTCOPY_RESUME) {
         ret = qemuMigrationSrcBeginResumePhase(conn, driver, vm, xmlin,
                                                cookieout, cookieoutlen, flags);
diff --git a/src/qemu/qemu_tpm.c b/src/qemu/qemu_tpm.c
index 07def3c840..fde15b7587 100644
--- a/src/qemu/qemu_tpm.c
+++ b/src/qemu/qemu_tpm.c
@@ -644,6 +644,32 @@ qemuTPMEmulatorBuildCommand(virDomainTPMDef *tpm,
         virCommandAddArgFormat(cmd, "pwdfd=%d,mode=aes-256-cbc", migpwdfile_fd);
     }
 
+    /* If swtpm supports it, start it with --migration release-lock-outgoing
+     * so it can migrate across shared storage if needed.
+     */
+    tpm->data.emulator.canMigrateWithSharedStorage = false;
+    if (virTPMSwtpmCapsGet(VIR_TPM_SWTPM_FEATURE_CMDARG_MIGRATION)) {
+        bool incoming = false;
+
+        if (incomingMigration && (flags & VIR_MIGRATE_TPM_SHARED_STORAGE))
+            incoming = true;
+        virCommandAddArg(cmd, "--migration");
+        virCommandAddArgFormat(cmd, "release-lock-outgoing%s",
+                               incoming ? ",incoming": "");
+        tpm->data.emulator.canMigrateWithSharedStorage = true;
+    } else {
+        /* Report an error if there's an incoming migration across shared
+         * storage and swtpm does not support the --migration option.
+         */
+        if (incomingMigration && (flags & VIR_MIGRATE_TPM_SHARED_STORAGE)) {
+            virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED,
+                _("%s (on destination side) does not support the --migration option "
+                  "needed for migration with shared storage"),
+                   swtpm);
+            goto error;
+        }
+    }
+
     return g_steal_pointer(&cmd);
 
  error:
@@ -967,6 +993,20 @@ qemuTPMEmulatorStart(virQEMUDriver *driver,
 }
 
 
+bool
+qemuTPMCanMigrateSharedStorage(virDomainDef *def)
+{
+    size_t i;
+
+    for (i = 0; i < def->ntpms; i++) {
+        if (def->tpms[i]->type == VIR_DOMAIN_TPM_TYPE_EMULATOR &&
+            !def->tpms[i]->data.emulator.canMigrateWithSharedStorage) {
+            return false;
+        }
+    }
+    return true;
+}
+
 /* ---------------------
  *  Module entry points
  * ---------------------
diff --git a/src/qemu/qemu_tpm.h b/src/qemu/qemu_tpm.h
index 410c9ec1c6..630fa7074f 100644
--- a/src/qemu/qemu_tpm.h
+++ b/src/qemu/qemu_tpm.h
@@ -57,3 +57,6 @@ int qemuExtTPMSetupCgroup(virQEMUDriver *driver,
                           virCgroup *cgroup)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3)
     G_GNUC_WARN_UNUSED_RESULT;
+
+bool qemuTPMCanMigrateSharedStorage(virDomainDef *def)
+    ATTRIBUTE_NONNULL(1);
-- 
2.37.3