[PATCH v15 10/28] tpm/tpm_tis: Allow locality to be set to a different value

Ross Philipson
2025-12-15T23:41:47Z

DRTM needs to be able to set the locality used by kernel. Provide
a one-shot function tpm_chip_set_locality() for the purpose.

Signed-off-by: Ross Philipson <ross.philipson@oracle.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
drivers/char/tpm/tpm-chip.c | 34 ++++++++++++++++++++++++++++++++-
drivers/char/tpm/tpm_tis_core.c | 2 ++
include/linux/tpm.h | 4 ++++
3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 6cb25862688f..3171684ca782 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->kernel_locality);
if (rc < 0)
return rc;

@@ -380,6 +380,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
}

chip->locality = -1;
+ chip->kernel_locality = 0;
return chip;

out:
@@ -700,3 +701,34 @@ void tpm_chip_unregister(struct tpm_chip *chip)
tpm_del_char_device(chip);
}
EXPORT_SYMBOL_GPL(tpm_chip_unregister);
+
+/**
+ * tpm_chip_set_locality() - Set the TPM locality kernel uses
+ * @chip: &tpm_chip instance
+ * @locality: new locality
+ *
+ * This a one-shot function. Returns zero or POSIX error on failure.
+ */
+int tpm_chip_set_locality(struct tpm_chip *chip, u8 locality)
+{
+ int ret;
+
+ if (locality >= TPM_MAX_LOCALITY)
+ return -EINVAL;
+
+ ret = tpm_try_get_ops(chip);
+ if (ret)
+ return ret;
+
+ if (!(chip->flags & TPM_CHIP_FLAG_SET_LOCALITY_ENABLED)) {
+ tpm_put_ops(chip);
+ return -EPERM;
+ }
+
+ chip->kernel_locality = locality;
+ chip->flags &= ~TPM_CHIP_FLAG_SET_LOCALITY_ENABLED;
+ tpm_put_ops(chip);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tpm_chip_set_locality);
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 14a7e60bfbb8..07e3b6e137f7 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -1125,6 +1125,8 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
if (IS_ERR(chip))
return PTR_ERR(chip);

+ chip->flags |= TPM_CHIP_FLAG_SET_LOCALITY_ENABLED;
+
#ifdef CONFIG_ACPI
chip->acpi_dev_handle = acpi_dev_handle;
#endif
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 87978cc584ee..11264d04a9ef 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -167,6 +167,8 @@ struct tpm_chip {

/* active locality */
int locality;
+ /* the locality used by kernel */
+ u8 kernel_locality;

#ifdef CONFIG_TCG_TPM2_HMAC
/* details for communication security via sessions */
@@ -205,6 +207,7 @@ enum tpm_chip_flags {
TPM_CHIP_FLAG_HWRNG_DISABLED = BIT(9),
TPM_CHIP_FLAG_DISABLE = BIT(10),
TPM_CHIP_FLAG_SYNC = BIT(11),
+ TPM_CHIP_FLAG_SET_LOCALITY_ENABLED = BIT(12),
};

#define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)
@@ -252,6 +255,7 @@ static inline ssize_t tpm_ret_to_err(ssize_t ret)
extern int tpm_is_tpm2(struct tpm_chip *chip);
extern __must_check int tpm_try_get_ops(struct tpm_chip *chip);
extern void tpm_put_ops(struct tpm_chip *chip);
+int tpm_chip_set_locality(struct tpm_chip *chip, u8 locality);
extern ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
size_t min_rsp_body_length, const char *desc);
extern int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
--
2.43.7