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

[Stefan Berger]

On 8/1/22 10:27, Ross Lagerwall via wrote:
> When resuming after a migration, the backend sends CMD_INIT to the
> emulator from the startup callback, then it sends the migration state

This startup hook is called upon TIS/CRB device reset, so this is likely 
called before the device state has been received.

> 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.

Ok, that's sufficient to start it up once all the state has been received.

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


Tested-by: Stefan Berger <stefanb@linux.ibm.com>

> ---
>   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);
>   }