[PATCH v2] tpm: Get TCG log from TPM2 ACPI table for tpm2 systems

[Jordan Hand <jordanhand22@xxxxxxxxx>]

For TPM2-based systems, retrieve the TCG log from the TPM2 ACPI table.

Signed-off-by: Jordan Hand <jordanhand22@xxxxxxxxx>
---
v2:
- Apologies, v1 had a silly compile error

 drivers/char/tpm/eventlog/acpi.c | 67 +++++++++++++++++++++++---------
 1 file changed, 48 insertions(+), 19 deletions(-)

diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c
index 63ada5e53f13..b945c4ff3af6 100644
--- a/drivers/char/tpm/eventlog/acpi.c
+++ b/drivers/char/tpm/eventlog/acpi.c
@@ -41,17 +41,31 @@ struct acpi_tcpa {
 	};
 };
 
+struct acpi_tpm2 {
+	struct acpi_table_header hdr;
+	u16 platform_class;
+	u16 reserved;
+	u64 control_area_addr;
+	u32 start_method;
+	u8 start_method_params[12];
+	u32 log_max_len;
+	u64 log_start_addr;
+} __packed;
+
 /* read binary bios log */
 int tpm_read_log_acpi(struct tpm_chip *chip)
 {
-	struct acpi_tcpa *buff;
+	struct acpi_table_header *buff;
+	struct acpi_tcpa *tcpa;
+	struct acpi_tpm2 *tpm2;
+
 	acpi_status status;
 	void __iomem *virt;
 	u64 len, start;
+	int log_type;
 	struct tpm_bios_log *log;
-
-	if (chip->flags & TPM_CHIP_FLAG_TPM2)
-		return -ENODEV;
+	bool is_tpm2 = chip->flags & TPM_CHIP_FLAG_TPM2;
+	acpi_string table_sig;
 
 	log = &chip->log;
 
@@ -61,26 +75,41 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
 	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);
+	/* Find TCPA or TPM2 entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
+	table_sig = is_tpm2 ? ACPI_SIG_TPM2 : ACPI_SIG_TCPA;
+	status = acpi_get_table(table_sig, 1, &buff);
 
 	if (ACPI_FAILURE(status))
 		return -ENODEV;
 
-	switch(buff->platform_class) {
-	case BIOS_SERVER:
-		len = buff->server.log_max_len;
-		start = buff->server.log_start_addr;
-		break;
-	case BIOS_CLIENT:
-	default:
-		len = buff->client.log_max_len;
-		start = buff->client.log_start_addr;
-		break;
+	/* If log_max_len and log_start_addr are set, start_method_params will
+	 * be 12 bytes, according to TCG ACPI spec. If start_method_params is
+	 * fewer than 12 bytes, the TCG log is not available
+	 */
+	if (is_tpm2 && (buff->length == sizeof(struct acpi_tpm2))) {
+		tpm2 = (struct acpi_tpm2 *)buff;
+		len = tpm2->log_max_len;
+		start = tpm2->log_start_addr;
+		log_type = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2;
+	} else {
+		tcpa = (struct acpi_tcpa *)buff;
+		switch (tcpa->platform_class) {
+		case BIOS_SERVER:
+			len = tcpa->server.log_max_len;
+			start = tcpa->server.log_start_addr;
+			break;
+		case BIOS_CLIENT:
+		default:
+			len = tcpa->client.log_max_len;
+			start = tcpa->client.log_start_addr;
+			break;
+		}
+		log_type = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
 	}
+
 	if (!len) {
-		dev_warn(&chip->dev, "%s: TCPA log area empty\n", __func__);
+		dev_warn(&chip->dev, "%s: %s log area empty\n",
+				table_sig, __func__);
 		return -EIO;
 	}
 
@@ -98,7 +127,7 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
 	memcpy_fromio(log->bios_event_log, virt, len);
 
 	acpi_os_unmap_iomem(virt, len);
-	return EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
+	return log_type;
 
 err:
 	kfree(log->bios_event_log);
-- 
2.20.1