linux-kernel - [PATCH v8 12/15] tpm: Add ability to set the preferred locality the TPM chip uses

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Message-Id: <20240214221847.2066632-13-ross.philipson@oracle.com>
Date: Wed, 14 Feb 2024 14:18:44 -0800
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
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,
        jarkko@...nel.org, jgg@...pe.ca, luto@...capital.net,
        nivedita@...m.mit.edu, herbert@...dor.apana.org.au,
        davem@...emloft.net, kanth.ghatraju@...cle.com,
        trenchboot-devel@...glegroups.com
Subject: [PATCH v8 12/15] tpm: Add ability to set the preferred 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 +++++++++++++++++++++++-
 drivers/char/tpm/tpm-interface.c | 15 +++++++++++++++
 drivers/char/tpm/tpm.h           |  1 +
 include/linux/tpm.h              | 10 ++++++++++
 4 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 42b1062e33cd..e4d591e8857b 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
@@ -368,6 +389,7 @@ 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 66b16d26eecc..7a758c6d6d09 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -273,6 +273,21 @@ 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);
+
 /**
  * tpm_pcr_read - read a PCR value from SHA1 bank
  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 61445f1dc46d..389b117e68c2 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -267,6 +267,7 @@ static inline void tpm_msleep(unsigned int delay_msec)
 int tpm_chip_bootstrap(struct tpm_chip *chip);
 int tpm_chip_start(struct tpm_chip *chip);
 void tpm_chip_stop(struct tpm_chip *chip);
+bool tpm_chip_preferred_locality(struct tpm_chip *chip, int locality);
 struct tpm_chip *tpm_find_get_ops(struct tpm_chip *chip);
 
 struct tpm_chip *tpm_chip_alloc(struct device *dev,
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 4ee9d13749ad..a61d4e5e4b2d 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -116,6 +116,12 @@ struct tpm_chip_seqops {
 	const struct seq_operations *seqops;
 };
 
+/*
+ * The maximum locality (0 - 4) for a TPM, as defined in section 3.2 of the
+ * Client Platform Profile Specification.
+ */
+#define TPM_MAX_LOCALITY		4
+
 struct tpm_chip {
 	struct device dev;
 	struct device devs;
@@ -170,6 +176,9 @@ struct tpm_chip {
 
 	/* active locality */
 	int locality;
+
+	/* preferred locality - default 0 */
+	int pref_locality;
 };
 
 #define TPM_HEADER_SIZE		10
@@ -421,6 +430,7 @@ static inline u32 tpm2_rc_value(u32 rc)
 #if defined(CONFIG_TCG_TPM) || defined(CONFIG_TCG_TPM_MODULE)
 
 extern int tpm_is_tpm2(struct tpm_chip *chip);
+extern bool tpm_preferred_locality(struct tpm_chip *chip, int locality);
 extern __must_check int tpm_try_get_ops(struct tpm_chip *chip);
 extern void tpm_put_ops(struct tpm_chip *chip);
 extern ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
-- 
2.39.3