2023-06-05 18:31:52

by Alexander Steffen

Subject: [PATCH v2 4/4] tpm_tis: Resend command to recover from data transfer errors

Similar to the transmission of TPM responses, also the transmission of TPM
commands may become corrupted. Instead of aborting when detecting such
issues, try resending the command again.

Signed-off-by: Alexander Steffen <[email protected]>
---
drivers/char/tpm/tpm_tis_core.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index a08768e55803..47073cc79b51 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -535,10 +535,18 @@ static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
int rc;
u32 ordinal;
unsigned long dur;
+ unsigned int try;

- rc = tpm_tis_send_data(chip, buf, len);
- if (rc < 0)
- return rc;
+ for (try = 0; try < TPM_RETRY; try++) {
+ rc = tpm_tis_send_data(chip, buf, len);
+ if (rc >= 0) {
+ /* Data transfer done successfully */
+ break;
+ } else if (rc != -EIO) {
+ /* Data transfer failed, not recoverable */
+ return rc;
+ }
+ }

/* go and do it */
rc = tpm_tis_write8(priv, TPM_STS(priv->locality), TPM_STS_GO);
--
2.34.1

2023-06-06 22:04:14

by Jarkko Sakkinen

Subject: Re: [PATCH v2 4/4] tpm_tis: Resend command to recover from data transfer errors

On Mon Jun 5, 2023 at 8:59 PM EEST, Alexander Steffen wrote:
> Similar to the transmission of TPM responses, also the transmission of TPM
> commands may become corrupted. Instead of aborting when detecting such
> issues, try resending the command again.
>
> Signed-off-by: Alexander Steffen <[email protected]>
> ---
> drivers/char/tpm/tpm_tis_core.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index a08768e55803..47073cc79b51 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -535,10 +535,18 @@ static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
> int rc;
> u32 ordinal;
> unsigned long dur;
> + unsigned int try;
>
> - rc = tpm_tis_send_data(chip, buf, len);
> - if (rc < 0)
> - return rc;
> + for (try = 0; try < TPM_RETRY; try++) {
> + rc = tpm_tis_send_data(chip, buf, len);
> + if (rc >= 0) {
> + /* Data transfer done successfully */
> + break;
> + } else if (rc != -EIO) {
> + /* Data transfer failed, not recoverable */
> + return rc;
> + }

Remove curly braces from the two statements above.

> + }
>
> /* go and do it */
> rc = tpm_tis_write8(priv, TPM_STS(priv->locality), TPM_STS_GO);
> --
> 2.34.1


BR, Jarkko