Re: [PATCH 0/2] tpm: Stop retrying TPMs that have stopped working

[Jarkko Sakkinen <jarkko@kernel.org>]

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On Thu, Nov 12, 2026 at 12:46:57AM +0200, Jarkko Sakkinen wrote:
> On Thu, Nov 12, 2026 at 12:43:59AM +0200, Jarkko Sakkinen wrote:
> > $ tpm2sh return-code 256
> > TPM_RC_INITIALIZE
> > 
> > I.e. TPM has not been properly initialized by TPM2_Startup().
> > 
> > I.e. TPM is also saying that it is *disabled*.
> > 
> > So acting on this proven fact  makes most sense to me.
> 
> 
> Actually, should we even disable TPM if it returns this error code
> already at the level of tpm_transmit(). It is a guaranteed dead-end
> to any possible TPM operation.
> 
> I.e. while this fixes hwrng issue I think it might be addressing the
> issue at a wrong level.

I leave room for figuring out 1/2 but for the second issue I would just
do what the attached patch does and call it a day.

Br, Jarkko

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From 093124e51a26de8191e21ce41988532ea7e0bc8a Mon Sep 17 00:00:00 2001
From: Jarkko Sakkinen <jarkko@kernel.org>
Date: Thu, 12 Nov 2026 03:55:00 +0200
Subject: [PATCH] tpm: Disable TPM on TPM_RC_INITIALIZE

If the TPM has been spuriously disabled, the game is over. Let's reflect
this truth with TPM_CHIP_FLAG_DISABLE.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 drivers/char/tpm/tpm-interface.c | 5 +++++
 drivers/char/tpm/tpm2-cmd.c      | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 470b2da3234e..1f1e22341155 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -256,6 +256,11 @@ ssize_t tpm_transmit(struct tpm_chip *chip, u8 *buf, size_t bufsiz)
 		if (rc == TPM2_RC_TESTING && cc == TPM2_CC_SELF_TEST)
 			break;
 
+		if (rc == TPM_RC_INITIALIZE) {
+			chip->flag |= TPM_CHIP_FLAG_DISABLE;
+			break;
+		}
+
 		if (delay_msec > TPM2_DURATION_LONG) {
 			if (rc == TPM2_RC_RETRY)
 				dev_err(&chip->dev, "in retry loop\n");
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 7fe00b4f8e7d..8d76e78cd92e 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -1021,6 +1021,8 @@ int tpm2_auto_startup(struct tpm_chip *chip)
 		goto out;
 
 	if (rc == TPM2_RC_INITIALIZE) {
+		chip->flags &= ~TPM_CHIP_FLAG_DISABLE;
+
 		rc = tpm2_startup(chip);
 		if (rc)
 			goto out;
-- 
2.47.3