Re: [PATCH] tpm_emulator: Report an error if chardev is missing

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

On 7/24/20 10:00 AM, Markus Armbruster wrote:
> Stefan Berger <stefanb@linux.vnet.ibm.com> writes:
>
>> This patch fixes the odd error reporting when trying to send a file
>> descriptor to the TPM emulator if one has not passed a valid chardev.
>>
>> $ x86_64-softmmu/qemu-system-x86_64 -tpmdev emulator,id=tpm0
>> qemu-system-x86_64: -tpmdev emulator,id=tpm0: tpm-emulator: Failed to send CMD_SET_DATAFD: Success
>> qemu-system-x86_64: -tpmdev emulator,id=tpm0: tpm-emulator: Could not cleanly shutdown the TPM: Success
>>
>> This is the new error report:
>>
>> $ x86_64-softmmu/qemu-system-x86_64 -tpmdev emulator,id=tpm0
>> qemu-system-x86_64: -tpmdev emulator,id=tpm0: tpm-emulator: missing chardev
>                                                  ~~~~~~~~~~~~~~
>
> The "tpm-emulator: " part looks superfluous.
>
> Hmm, many error messages in this file have it.  Feel free to keep it
> now for consistency, and clean it up later.
>
> We usually report missing option parameters like "parameter 'chardev' is
> missing".  Please consider sticking to that.

Fixed.


>
>> This change does not hide the display of supported TPM types if a non-existent type is passed:
>>
>> $ x86_64-softmmu/qemu-system-x86_64 -tpmdev nonexistent,id=tpm0
>> qemu-system-x86_64: -tpmdev nonexistent,id=tpm0: Parameter 'type' expects a TPM backend type
>> Supported TPM types (choose only one):
>>   passthrough   Passthrough TPM backend driver
>>      emulator   TPM emulator backend driver
>>
>> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
>> ---
>>   backends/tpm/tpm_emulator.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/backends/tpm/tpm_emulator.c b/backends/tpm/tpm_emulator.c
>> index 9605339f93..55cbc9c60e 100644
>> --- a/backends/tpm/tpm_emulator.c
>> +++ b/backends/tpm/tpm_emulator.c
>> @@ -568,6 +568,9 @@ static int tpm_emulator_handle_device_opts(TPMEmulator *tpm_emu, QemuOpts *opts)
>>           }
>>   
>>           tpm_emu->options->chardev = g_strdup(value);
>> +    } else {
>> +        error_report("tpm-emulator: missing chardev");
>> +        goto err;
>>       }
>>   
>>       if (tpm_emulator_prepare_data_fd(tpm_emu) < 0) {
> This is minimally invasive.
>
> I'd prefer
>
>         Error *err = NULL;
>         const char *value;
>         Chardev *dev;
>
>         value = qemu_opt_get(opts, "chardev");
>         if (!value) {
>             error_report("tpm-emulator: missing chardev");
>             goto err;
>         }
>
>         dev = qemu_chr_find(value);
>         if (!dev) {
>             error_report("tpm-emulator: tpm chardev '%s' not found.", value);
>             goto err;
>         }
>
> Your choice.


Ok, changed it to this.


>
>> @@ -925,6 +928,11 @@ static void tpm_emulator_shutdown(TPMEmulator *tpm_emu)
>>   {
>>       ptm_res res;
>>   
>> +    if (!tpm_emu->options->chardev) {
>> +        /* was never properly initialized */
>> +        return;
>> +    }
>> +
> Is this still reachable?  If yes, how?


tpm_emulator_inst_finalize still runs.


Sending V2. Thanks.

>
> If not, drop the hunk and have my
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
>
>>       if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SHUTDOWN, &res, 0, sizeof(res)) < 0) {
>>           error_report("tpm-emulator: Could not cleanly shutdown the TPM: %s",
>>                        strerror(errno));