Re: [PATCH v9 14/19] tpm: Ensure tpm is in known state at startup

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On 6/4/24 16:14, Jarkko Sakkinen wrote:
On Fri May 31, 2024 at 4:03 AM EEST, Ross Philipson wrote:
From: "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>

When tis core initializes, it assumes all localities are closed. There

s/tis_core/tpm_tis_core/

Ack.

are cases when this may not be the case. This commit addresses this by
ensuring all localities are closed before initializing begins.

Signed-off-by: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ross Philipson <ross.philipson@xxxxxxxxxx>
---
  drivers/char/tpm/tpm_tis_core.c | 11 ++++++++++-
  include/linux/tpm.h             |  6 ++++++
  2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 7c1761bd6000..9fb53bb3e73f 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -1104,7 +1104,7 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
  	u32 intmask;
  	u32 clkrun_val;
  	u8 rid;
-	int rc, probe;
+	int rc, probe, i;
  	struct tpm_chip *chip;
chip = tpmm_chip_alloc(dev, &tpm_tis);
@@ -1166,6 +1166,15 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
  		goto out_err;
  	}
+ /*
+	 * There are environments, like Intel TXT, that may leave a TPM

What else at this point than Intel TXT reflecting the state of the
mainline?

Leaving the TPM in Locality 2 is a requirement of the TCG D-RTM specification. This will be the situation for AMD and Arm as well. The comment can be updated to ref the TCG spec instead of a specific implementation.

+	 * locality open. Close all localities to start from a known state.
+	 */
+	for (i = 0; i <= TPM_MAX_LOCALITY; i++) {
+		if (check_locality(chip, i))
+			tpm_tis_relinquish_locality(chip, i);
+	}

To be strict this should be enabled only for x86 platforms.

I.e. should be flagged.

As mentioned above, this will also affect Arm.

+
  	/* Take control of the TPM's interrupt hardware and shut it off */
  	rc = tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &intmask);
  	if (rc < 0)
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index c17e4efbb2e5..363f7078c3a9 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -147,6 +147,12 @@ struct tpm_chip_seqops {
   */
  #define TPM2_MAX_CONTEXT_SIZE 4096
+/*
+ * 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;


BR, Jarkko

v/r,
dps




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