Re: [PATCH 2/2] qemu: tpm: Remove TPM state after successful migration

[Stefan Berger]

On 10/3/22 11:20, Michal Prívozník wrote:

On 8/23/22 18:28, Stefan Berger wrote:

This patch 'fixes' the behavior of the persistent_state TPM domain XML
attribute that intends to preserve the state of the TPM but should not
keep the state around on all the hosts a VM has been migrated to. It
removes the TPM state directory structure from the source host upon
successful migration when non-shared storage is used. Similarly, it
removes it from the destination host upon migration failure when
non-shared storage is used.

Signed-off-by: Stefan Berger <stef...@linux.ibm.com>
---
  src/qemu/qemu_migration.c | 14 +++++++++++---
  src/qemu/qemu_tpm.h       | 12 ++++++++++++
  2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 7f69991e2b..355a2cb5c7 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"
@@ -4006,6 +4007,7 @@ qemuMigrationSrcConfirm(virQEMUDriver *driver,
      qemuMigrationJobPhase phase;
      g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
      qemuDomainObjPrivate *priv = vm->privateData;
+    virDomainUndefineFlagsValues undefFlags = 0;

unsigned int undefFlags = 0; ?

      int ret = -1;

VIR_DEBUG("vm=%p, flags=0x%x, cancelled=%d", vm, flags, cancelled);

@@ -4054,7 +4056,9 @@ qemuMigrationSrcConfirm(virQEMUDriver *driver,
              virDomainDeleteConfig(cfg->configDir, cfg->autostartDir, vm);
              vm->persistent = 0;
          }
-        qemuDomainRemoveInactive(driver, vm, 0);
+        if (!qemuTPMCheckKeepTPMStateMigrationSrcSuccess(vm))
+            undefFlags |= VIR_DOMAIN_UNDEFINE_TPM;
+        qemuDomainRemoveInactive(driver, vm, undefFlags);
      }

cleanup:

@@ -6590,6 +6594,7 @@ qemuMigrationDstFinishActive(virQEMUDriver *driver,
      virObjectEvent *event;
      bool inPostCopy = false;
      bool doKill = priv->job.phase != QEMU_MIGRATION_PHASE_FINISH_RESUME;
+    virDomainUndefineFlagsValues undefFlags = 0;
      int rc;

VIR_DEBUG("vm=%p, flags=0x%lx, retcode=%d",

@@ -6666,8 +6671,11 @@ qemuMigrationDstFinishActive(virQEMUDriver *driver,
                                   jobPriv->migParams, priv->job.apiFlags);
      }

- if (!virDomainObjIsActive(vm))

-        qemuDomainRemoveInactive(driver, vm, 0);
+    if (!virDomainObjIsActive(vm)) {
+        if (!qemuTPMCheckKeepTPMStateMigrationDstFailure(vm))
+            undefFlags |= VIR_DOMAIN_UNDEFINE_TPM;
+        qemuDomainRemoveInactive(driver, vm, undefFlags);
+    }

virErrorRestore(&orig_err);

      return NULL;
diff --git a/src/qemu/qemu_tpm.h b/src/qemu/qemu_tpm.h
index f068f3ca5a..c5d8774f07 100644
--- a/src/qemu/qemu_tpm.h
+++ b/src/qemu/qemu_tpm.h
@@ -56,3 +56,15 @@ int qemuExtTPMSetupCgroup(virQEMUDriver *driver,
                            virCgroup *cgroup)
      ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3)
      G_GNUC_WARN_UNUSED_RESULT;
+
+static inline bool
+qemuTPMCheckKeepTPMStateMigrationSrcSuccess(virDomainObj *vm G_GNUC_UNUSED)
+{
+    return false;
+}
+
+static inline bool
+qemuTPMCheckKeepTPMStateMigrationDstFailure(virDomainObj *vm G_GNUC_UNUSED)
+{
+    return false;
+}

Yeah, I know where you're headed with these two, but G_GNUC_UNUSED
breaks syntax-check. And they can be added in shared storage state series.

But you agree to the expressive names? I am asking because they will re-appear 
then?

Michal