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

ross.philipson@xxxxxxxxxx · Tue, 4 Jun 2024 16:04:15 -0700

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@xxxxxxxxxx>
---
   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









