[PATCH v13 16/19] tpm, tpm_tis: Allow locality to be set to a different value

Ross Philipson
2025-04-10T20:50:15Z

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 | 33 ++++++++++++++++++++++++++++++++-
drivers/char/tpm/tpm_tis_core.c | 2 ++
include/linux/tpm.h | 4 ++++
3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 7df7abaf3e52..ac200514c4d7 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;

@@ -374,6 +374,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
}

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

out:
@@ -689,3 +690,33 @@ 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 < 0 || 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 -EINVAL;
+ }
+
+ 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 f9a3489313b4..fd17cccb8abf 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -1117,6 +1117,8 @@ 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 c5a4a2d7dd15..9f910d3bc2e4 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -207,6 +207,8 @@ 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 */
@@ -354,6 +356,7 @@ enum tpm_chip_flags {
TPM_CHIP_FLAG_SUSPENDED = BIT(8),
TPM_CHIP_FLAG_HWRNG_DISABLED = BIT(9),
TPM_CHIP_FLAG_DISABLE = BIT(10),
+ TPM_CHIP_FLAG_SET_LOCALITY_ENABLED = BIT(11),
};

#define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)
@@ -447,6 +450,7 @@ static inline u32 tpm2_rc_value(u32 rc)
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,
--
2.39.3