tpm: Fix handling of missing event log

The event log is an optional firmware feature, if the firmware
does not support it then the securityfs files should not be created
and no other notification given.

- Uniformly return -ENODEV from the tpm_bios_log_setup cone if
  no event log is detected.
- Check in ACPI if this node was discovered via ACPI.
- Improve the check in OF to make sure there is a parent and to
  fail detection if the two log properties are not declared
- Pass through all other error codes instead of filtering just some

Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

4 files changed, 26 insertions, 21 deletions

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 3f27753d96aa..7a4869151d3b 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -346,7 +346,7 @@ int tpm_chip_register(struct tpm_chip *chip)
 	tpm_sysfs_add_device(chip);
 
 	rc = tpm_bios_log_setup(chip);
-	if (rc == -ENODEV)
+	if (rc != 0 && rc != -ENODEV)
 		return rc;
 
 	tpm_add_ppi(chip);
diff --git a/drivers/char/tpm/tpm_acpi.c b/drivers/char/tpm/tpm_acpi.c
index 0cb43ef5f79a..b7718c95fd0b 100644
--- a/drivers/char/tpm/tpm_acpi.c
+++ b/drivers/char/tpm/tpm_acpi.c
@@ -56,12 +56,18 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
 
 	log = &chip->log;
 
+	/* Unfortuntely ACPI does not associate the event log with a specific
+	 * TPM, like PPI. Thus all ACPI TPMs will read the same log.
+	 */
+	if (!chip->acpi_dev_handle)
+		return -ENODEV;
+
 	/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
 	status = acpi_get_table(ACPI_SIG_TCPA, 1,
 				(struct acpi_table_header **)&buff);
 
 	if (ACPI_FAILURE(status))
-		return -EIO;
+		return -ENODEV;
 
 	switch(buff->platform_class) {
 	case BIOS_SERVER:
diff --git a/drivers/char/tpm/tpm_eventlog.c b/drivers/char/tpm/tpm_eventlog.c
index 34f0921f0203..c73f88cdeadf 100644
--- a/drivers/char/tpm/tpm_eventlog.c
+++ b/drivers/char/tpm/tpm_eventlog.c
@@ -368,14 +368,21 @@ static int tpm_read_log(struct tpm_chip *chip)
 	}
 
 	rc = tpm_read_log_acpi(chip);
-	if ((rc == 0) || (rc == -ENOMEM))
+	if (rc != -ENODEV)
 		return rc;
 
-	rc = tpm_read_log_of(chip);
-
-	return rc;
+	return tpm_read_log_of(chip);
 }
 
+/*
+ * tpm_bios_log_setup() - Read the event log from the firmware
+ * @chip: TPM chip to use.
+ *
+ * If an event log is found then the securityfs files are setup to
+ * export it to userspace, otherwise nothing is done.
+ *
+ * Returns -ENODEV if the firmware has no event log.
+ */
 int tpm_bios_log_setup(struct tpm_chip *chip)
 {
 	const char *name = dev_name(&chip->dev);
@@ -386,15 +393,8 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
 		return 0;
 
 	rc = tpm_read_log(chip);
-	/*
-	 * read_log failure means event log is not supported except for ENOMEM.
-	 */
-	if (rc < 0) {
-		if (rc == -ENOMEM)
-			return -ENODEV;
-		else
-			return rc;
-	}
+	if (rc)
+		return rc;
 
 	cnt = 0;
 	chip->bios_dir[cnt] = securityfs_create_dir(name, NULL);
diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
index 36df9df4c472..7dee42d7b5e0 100644
--- a/drivers/char/tpm/tpm_of.c
+++ b/drivers/char/tpm/tpm_of.c
@@ -29,13 +29,16 @@ int tpm_read_log_of(struct tpm_chip *chip)
 	struct tpm_bios_log *log;
 
 	log = &chip->log;
-	if (chip->dev.parent->of_node)
+	if (chip->dev.parent && chip->dev.parent->of_node)
 		np = chip->dev.parent->of_node;
 	else
 		return -ENODEV;
 
 	sizep = of_get_property(np, "linux,sml-size", NULL);
-	if (sizep == NULL)
+	basep = of_get_property(np, "linux,sml-base", NULL);
+	if (sizep == NULL && basep == NULL)
+		return -ENODEV;
+	if (sizep == NULL || basep == NULL)
 		return -EIO;
 
 	if (*sizep == 0) {
@@ -43,10 +46,6 @@ int tpm_read_log_of(struct tpm_chip *chip)
 		return -EIO;
 	}
 
-	basep = of_get_property(np, "linux,sml-base", NULL);
-	if (basep == NULL)
-		return -EIO;
-
 	log->bios_event_log = kmalloc(*sizep, GFP_KERNEL);
 	if (!log->bios_event_log)
 		return -ENOMEM;