Re: [PATCH] tpm_emulator: Avoid double initialization during migration

[Marc-André Lureau]

Hi

On Mon, Aug 1, 2022 at 6:28 PM Ross Lagerwall via <qemu-devel@nongnu.org> wrote:

When resuming after a migration, the backend sends CMD_INIT to the
emulator from the startup callback, then it sends the migration state
from the vmstate to the emulator, then it sends CMD_INIT again. Skip the
first CMD_INIT during a migration to avoid initializing the TPM twice.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>

lgtm

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

There are no visible bugs/symptoms, I suppose?

 

---
 backends/tpm/tpm_emulator.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/backends/tpm/tpm_emulator.c b/backends/tpm/tpm_emulator.c
index 87d061e9bb..9b50c5b3e2 100644
--- a/backends/tpm/tpm_emulator.c
+++ b/backends/tpm/tpm_emulator.c
@@ -32,6 +32,7 @@
 #include "qemu/sockets.h"
 #include "qemu/lockable.h"
 #include "io/channel-socket.h"
+#include "sysemu/runstate.h"
 #include "sysemu/tpm_backend.h"
 #include "sysemu/tpm_util.h"
 #include "tpm_int.h"
@@ -383,6 +384,15 @@ err_exit:

 static int tpm_emulator_startup_tpm(TPMBackend *tb, size_t buffersize)
 {
+    /* TPM startup will be done from post_load hook */
+    if (runstate_check(RUN_STATE_INMIGRATE)) {
+        if (buffersize != 0) {
+            return tpm_emulator_set_buffer_size(tb, buffersize, NULL);
+        }
+
+        return 0;
+    }
+
     return tpm_emulator_startup_tpm_resume(tb, buffersize, false);
 }

--
2.31.1

--

Marc-André Lureau