Re: [PATCH v9 16/19] tpm: Add ability to set the preferred locality the TPM chip uses

ross.philipson
2024-06-04T23:05:21Z

On 6/4/24 3:50 PM, Jarkko Sakkinen wrote:
> On Wed Jun 5, 2024 at 1:14 AM EEST, wrote:
>> On 6/4/24 1:27 PM, Jarkko Sakkinen wrote:
>>> On Fri May 31, 2024 at 4:03 AM EEST, Ross Philipson wrote:
>>>> Curently the locality is hard coded to 0 but for DRTM support, access
>>>> is needed to localities 1 through 4.
>>>>
>>>> Signed-off-by: Ross Philipson <ross.philipson@oracle.com>
>>>> ---
>>>> drivers/char/tpm/tpm-chip.c | 24 +++++++++++++++++++++++-
>>>> drivers/char/tpm/tpm-interface.c | 15 +++++++++++++++
>>>> drivers/char/tpm/tpm.h | 1 +
>>>> include/linux/tpm.h | 4 ++++
>>>> 4 files changed, 43 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
>>>> index 854546000c92..73eac54d61fb 100644
>>>> --- a/drivers/char/tpm/tpm-chip.c
>>>> +++ b/drivers/char/tpm/tpm-chip.c
>>>> @@ -44,7 +44,7 @@ static int tpm_request_locality(struct tpm_chip *chip)
>>>> if (!chip->ops->request_locality)
>>>> return 0;
>>>>
>>>> - rc = chip->ops->request_locality(chip, 0);
>>>> + rc = chip->ops->request_locality(chip, chip->pref_locality);
>>>> if (rc < 0)
>>>> return rc;
>>>>
>>>> @@ -143,6 +143,27 @@ void tpm_chip_stop(struct tpm_chip *chip)
>>>> }
>>>> EXPORT_SYMBOL_GPL(tpm_chip_stop);
>>>>
>>>> +/**
>>>> + * tpm_chip_preferred_locality() - set the TPM chip preferred locality to open
>>>> + * @chip: a TPM chip to use
>>>> + * @locality: the preferred locality
>>>> + *
>>>> + * Return:
>>>> + * * true - Preferred locality set
>>>> + * * false - Invalid locality specified
>>>> + */
>>>> +bool tpm_chip_preferred_locality(struct tpm_chip *chip, int locality)
>>>> +{
>>>> + if (locality < 0 || locality >=TPM_MAX_LOCALITY)
>>>> + return false;
>>>> +
>>>> + mutex_lock(&chip->tpm_mutex);
>>>> + chip->pref_locality = locality;
>>>> + mutex_unlock(&chip->tpm_mutex);
>>>> + return true;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(tpm_chip_preferred_locality);
>>>> +
>>>> /**
>>>> * tpm_try_get_ops() - Get a ref to the tpm_chip
>>>> * @chip: Chip to ref
>>>> @@ -374,6 +395,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
>>>> }
>>>>
>>>> chip->locality = -1;
>>>> + chip->pref_locality = 0;
>>>> return chip;
>>>>
>>>> out:
>>>> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
>>>> index 5da134f12c9a..35f14ccecf0e 100644
>>>> --- a/drivers/char/tpm/tpm-interface.c
>>>> +++ b/drivers/char/tpm/tpm-interface.c
>>>> @@ -274,6 +274,21 @@ int tpm_is_tpm2(struct tpm_chip *chip)
>>>> }
>>>> EXPORT_SYMBOL_GPL(tpm_is_tpm2);
>>>>
>>>> +/**
>>>> + * tpm_preferred_locality() - set the TPM chip preferred locality to open
>>>> + * @chip: a TPM chip to use
>>>> + * @locality: the preferred locality
>>>> + *
>>>> + * Return:
>>>> + * * true - Preferred locality set
>>>> + * * false - Invalid locality specified
>>>> + */
>>>> +bool tpm_preferred_locality(struct tpm_chip *chip, int locality)
>>>> +{
>>>> + return tpm_chip_preferred_locality(chip, locality);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(tpm_preferred_locality);
>>>
>>> What good does this extra wrapping do?
>>>
>>> tpm_set_default_locality() and default_locality would make so much more
>>> sense in any case.
>>
>> Are you mainly just talking about my naming choices here and in the
>> follow-on response? Can you clarify what you are requesting?
>
> I'd prefer:
>
> 1. Name the variable as default_locality.
> 2. Only create a single expored to function to tpm-chip.c:
> tpm_chip_set_default_locality().
> 3. Call this function in all call sites.
>
> "tpm_preferred_locality" should be just removed, as tpm_chip_*
> is exported anyway.

Ok got it, thanks.

>
> BR, Jarkko