linux-kernel - [PATCH v8 13/15] tpm: Add sysfs interface to allow setting and querying the preferred locality

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Date: Wed, 14 Feb 2024 14:18:45 -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 13/15] tpm: Add sysfs interface to allow setting and querying the preferred locality

Expose a sysfs interface to allow user mode to set and query the preferred
locality for the TPM chip.

Signed-off-by: Ross Philipson <ross.philipson@...cle.com>
---
 drivers/char/tpm/tpm-sysfs.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 54c71473aa29..c43630d0996e 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -309,6 +309,34 @@ static ssize_t tpm_version_major_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(tpm_version_major);
 
+static ssize_t preferred_locality_show(struct device *dev,
+				       struct device_attribute *attr, char *buf)
+{
+	struct tpm_chip *chip = to_tpm_chip(dev);
+
+	return sprintf(buf, "%d\n", chip->pref_locality);
+}
+
+static ssize_t preferred_locality_store(struct device *dev, struct device_attribute *attr,
+					const char *buf, size_t count)
+{
+	struct tpm_chip *chip = to_tpm_chip(dev);
+	unsigned int locality;
+
+	if (kstrtouint(buf, 0, &locality))
+		return -ERANGE;
+
+	if (locality >= TPM_MAX_LOCALITY)
+		return -ERANGE;
+
+	if (tpm_chip_preferred_locality(chip, (int)locality))
+		return count;
+	else
+		return 0;
+}
+
+static DEVICE_ATTR_RW(preferred_locality);
+
 static struct attribute *tpm1_dev_attrs[] = {
 	&dev_attr_pubek.attr,
 	&dev_attr_pcrs.attr,
@@ -321,11 +349,13 @@ static struct attribute *tpm1_dev_attrs[] = {
 	&dev_attr_durations.attr,
 	&dev_attr_timeouts.attr,
 	&dev_attr_tpm_version_major.attr,
+	&dev_attr_preferred_locality.attr,
 	NULL,
 };
 
 static struct attribute *tpm2_dev_attrs[] = {
 	&dev_attr_tpm_version_major.attr,
+	&dev_attr_preferred_locality.attr,
 	NULL
 };
 
-- 
2.39.3