linux-kernel - [PATCH v10 17/20] tpm: Add ability to set the default locality the TPM chip uses

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Message-Id: <20240826223835.3928819-18-ross.philipson@oracle.com>
Date: Mon, 26 Aug 2024 15:38:32 -0700
From: Ross Philipson <ross.philipson@...cle.com>
To: linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-integrity@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-crypto@...r.kernel.org, kexec@...ts.infradead.org,
        linux-efi@...r.kernel.org, iommu@...ts.linux-foundation.org
Cc: ross.philipson@...cle.com, dpsmith@...rtussolutions.com,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        dave.hansen@...ux.intel.com, ardb@...nel.org, mjg59@...f.ucam.org,
        James.Bottomley@...senpartnership.com, peterhuewe@....de,
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        nivedita@...m.mit.edu, herbert@...dor.apana.org.au,
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        dwmw2@...radead.org, baolu.lu@...ux.intel.com,
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        trenchboot-devel@...glegroups.com
Subject: [PATCH v10 17/20] tpm: Add ability to set the default locality the TPM chip uses

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@...cle.com>
---
 drivers/char/tpm/tpm-chip.c | 24 +++++++++++++++++++++++-
 include/linux/tpm.h         |  4 ++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 854546000c92..1ca390a742ed 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->default_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_set_default_locality() - set the TPM chip default locality to open
+ * @chip:	a TPM chip to use
+ * @locality:   the default locality to set
+ *
+ * Return:
+ * * true      - Preferred locality set
+ * * false     - Invalid locality specified
+ */
+bool tpm_chip_set_default_locality(struct tpm_chip *chip, int locality)
+{
+	if (locality < 0 || locality >=TPM_MAX_LOCALITY)
+		return false;
+
+	mutex_lock(&chip->tpm_mutex);
+	chip->default_locality = locality;
+	mutex_unlock(&chip->tpm_mutex);
+	return true;
+}
+EXPORT_SYMBOL_GPL(tpm_chip_set_default_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->default_locality = 0;
 	return chip;
 
 out:
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 98f2c7c1c52e..83e94b2f0cef 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -219,6 +219,9 @@ struct tpm_chip {
 	u8 null_ec_key_y[EC_PT_SZ];
 	struct tpm2_auth *auth;
 #endif
+
+	/* preferred locality - default 0 */
+	int default_locality;
 };
 
 #define TPM_HEADER_SIZE		10
@@ -446,6 +449,7 @@ 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);
+extern bool tpm_chip_set_default_locality(struct tpm_chip *chip, int 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