Re: [PATCH v4 2/2] tmp_emulator: improve and fix use of errp

[Stefan Berger <stefanb@linux.ibm.com>]

On 10/28/25 9:07 AM, Vladimir Sementsov-Ogievskiy wrote:
> tpm_emulator_post_load() and tpm_emulator_set_state_blobs() has
> error paths, where they return negative value, but do not set
> errp.
> 
> To fix that, we also have to convert several other functions to
> set errp instead of error_reporting.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> ---
>   backends/tpm/tpm_emulator.c | 63 +++++++++++++++++++++++--------------
>   1 file changed, 39 insertions(+), 24 deletions(-)
> 
> diff --git a/backends/tpm/tpm_emulator.c b/backends/tpm/tpm_emulator.c
> index dacfca5ab7..6abe9872e6 100644
> --- a/backends/tpm/tpm_emulator.c
> +++ b/backends/tpm/tpm_emulator.c
> @@ -308,22 +308,22 @@ static int tpm_emulator_check_caps(TPMEmulator *tpm_emu)
>       return 0;
>   }
>   
> -static int tpm_emulator_stop_tpm(TPMBackend *tb)
> +static int tpm_emulator_stop_tpm(TPMBackend *tb, Error **errp)
>   {
>       TPMEmulator *tpm_emu = TPM_EMULATOR(tb);
>       ptm_res res;
>   
>       if (tpm_emulator_ctrlcmd(tpm_emu, CMD_STOP, &res, 0,
>                                sizeof(ptm_res), sizeof(res)) < 0) {
> -        error_report("tpm-emulator: Could not stop TPM: %s",
> -                     strerror(errno));
> +        error_setg(errp, "tpm-emulator: Could not stop TPM: %s",
> +                   strerror(errno));
>           return -1;
>       }
>   
>       res = be32_to_cpu(res);
>       if (res) {
> -        error_report("tpm-emulator: TPM result for CMD_STOP: 0x%x %s", res,
> -                     tpm_emulator_strerror(res));
> +        error_setg(errp, "tpm-emulator: TPM result for CMD_STOP: 0x%x %s", res,
> +                   tpm_emulator_strerror(res));
>           return -1;
>       }
>   
> @@ -362,12 +362,13 @@ static int tpm_emulator_lock_storage(TPMEmulator *tpm_emu)
>   
>   static int tpm_emulator_set_buffer_size(TPMBackend *tb,
>                                           size_t wanted_size,
> -                                        size_t *actual_size)
> +                                        size_t *actual_size,
> +                                        Error **errp)
>   {
>       TPMEmulator *tpm_emu = TPM_EMULATOR(tb);
>       ptm_setbuffersize psbs;
>   
> -    if (tpm_emulator_stop_tpm(tb) < 0) {
> +    if (tpm_emulator_stop_tpm(tb, errp) < 0) {
>           return -1;
>       }
>   
> @@ -376,16 +377,17 @@ static int tpm_emulator_set_buffer_size(TPMBackend *tb,
>       if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_BUFFERSIZE, &psbs,
>                                sizeof(psbs.u.req), sizeof(psbs.u.resp.tpm_result),
>                                sizeof(psbs.u.resp)) < 0) {
> -        error_report("tpm-emulator: Could not set buffer size: %s",
> -                     strerror(errno));
> +        error_setg(errp, "tpm-emulator: Could not set buffer size: %s",
> +                   strerror(errno));
>           return -1;
>       }
>   
>       psbs.u.resp.tpm_result = be32_to_cpu(psbs.u.resp.tpm_result);
>       if (psbs.u.resp.tpm_result != 0) {
> -        error_report("tpm-emulator: TPM result for set buffer size : 0x%x %s",
> -                     psbs.u.resp.tpm_result,
> -                     tpm_emulator_strerror(psbs.u.resp.tpm_result));
> +        error_setg(errp,
> +                   "tpm-emulator: TPM result for set buffer size : 0x%x %s",
> +                   psbs.u.resp.tpm_result,
> +                   tpm_emulator_strerror(psbs.u.resp.tpm_result));
>           return -1;
>       }
>   
> @@ -402,7 +404,7 @@ static int tpm_emulator_set_buffer_size(TPMBackend *tb,
>   }
>   
>   static int tpm_emulator_startup_tpm_resume(TPMBackend *tb, size_t buffersize,
> -                                     bool is_resume)
> +                                           bool is_resume, Error **errp)
>   {
>       TPMEmulator *tpm_emu = TPM_EMULATOR(tb);
>       ptm_init init = {
> @@ -413,7 +415,7 @@ static int tpm_emulator_startup_tpm_resume(TPMBackend *tb, size_t buffersize,
>       trace_tpm_emulator_startup_tpm_resume(is_resume, buffersize);
>   
>       if (buffersize != 0 &&
> -        tpm_emulator_set_buffer_size(tb, buffersize, NULL) < 0) {
> +        tpm_emulator_set_buffer_size(tb, buffersize, NULL, errp) < 0) {
>           goto err_exit;
>       }
>   
> @@ -424,15 +426,15 @@ static int tpm_emulator_startup_tpm_resume(TPMBackend *tb, size_t buffersize,
>       if (tpm_emulator_ctrlcmd(tpm_emu, CMD_INIT, &init, sizeof(init),
>                                sizeof(init.u.resp.tpm_result),
>                                sizeof(init)) < 0) {
> -        error_report("tpm-emulator: could not send INIT: %s",
> -                     strerror(errno));
> +        error_setg(errp, "tpm-emulator: could not send INIT: %s",
> +                   strerror(errno));
>           goto err_exit;
>       }
>   
>       res = be32_to_cpu(init.u.resp.tpm_result);
>       if (res) {
> -        error_report("tpm-emulator: TPM result for CMD_INIT: 0x%x %s", res,
> -                     tpm_emulator_strerror(res));
> +        error_setg(errp, "tpm-emulator: TPM result for CMD_INIT: 0x%x %s", res,
> +                   tpm_emulator_strerror(res));
>           goto err_exit;
>       }
>       return 0;
> @@ -441,18 +443,31 @@ err_exit:
>       return -1;
>   }
>   
> -static int tpm_emulator_startup_tpm(TPMBackend *tb, size_t buffersize)
> +static int do_tpm_emulator_startup_tpm(TPMBackend *tb, size_t buffersize,
> +                                       Error **errp)
>   {
>       /* 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 tpm_emulator_set_buffer_size(tb, buffersize, NULL, errp);
>           }
>   
>           return 0;
>       }
>   
> -    return tpm_emulator_startup_tpm_resume(tb, buffersize, false);
> +    return tpm_emulator_startup_tpm_resume(tb, buffersize, false, errp);
> +}
> +
> +static int tpm_emulator_startup_tpm(TPMBackend *tb, size_t buffersize)
> +{
> +    Error *local_err = NULL;
> +    int ret = do_tpm_emulator_startup_tpm(tb, buffersize, &local_err);
> +
> +    if (ret < 0) {
> +        error_report_err(local_err);
> +    }
> +
> +    return ret;
>   }
>   
>   static bool tpm_emulator_get_tpm_established_flag(TPMBackend *tb)
> @@ -546,7 +561,7 @@ static size_t tpm_emulator_get_buffer_size(TPMBackend *tb)
>   {
>       size_t actual_size;
>   
> -    if (tpm_emulator_set_buffer_size(tb, 0, &actual_size) < 0) {
> +    if (tpm_emulator_set_buffer_size(tb, 0, &actual_size, NULL) < 0) {

You would have to pass a &local_err here as well otherwise the error is 
ignored.

>           return 4096;
>       }
>   
> @@ -889,7 +904,7 @@ static int tpm_emulator_set_state_blobs(TPMBackend *tb, Error **errp)
>   
>       trace_tpm_emulator_set_state_blobs();
>   
> -    if (tpm_emulator_stop_tpm(tb) < 0) {
> +    if (tpm_emulator_stop_tpm(tb, errp) < 0) {
>           trace_tpm_emulator_set_state_blobs_error("Could not stop TPM");
>           return -EIO;
>       }
> @@ -960,7 +975,7 @@ static int tpm_emulator_post_load(void *opaque, int version_id, Error **errp)
>           return ret;
>       }
>   
> -    if (tpm_emulator_startup_tpm_resume(tb, 0, true) < 0) {
> +    if (tpm_emulator_startup_tpm_resume(tb, 0, true, errp) < 0) {
>           return -EIO;
>       }
>   

Thank you.

    Stefan