linux-kernel - Re: [PATCH v2 2/2] tpm: Add field upgrade mode support for Infineon TPM2 modules

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Message-ID: <YoKZlTwRnEfzgApR@kernel.org>
Date:   Mon, 16 May 2022 21:36:05 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@...ineon.com>
Cc:     linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        peterhuewe@....de, jgg@...pe.ca, jsnitsel@...hat.com,
        nayna@...ux.vnet.ibm.com, alexander.steffen@...ineon.com
Subject: Re: [PATCH v2 2/2] tpm: Add field upgrade mode support for Infineon
 TPM2 modules

On Fri, May 13, 2022 at 03:41:53PM +0200, Stefan Mahnke-Hartmann wrote:
> TPM2_GetCapability with a capability that has the property type value
> of TPM_PT_TOTAL_COMMANDS returns a zero length list, when an Infineon
> TPM2 is in field upgrade mode.
> Since an Infineon TPM2.0 in field upgrade mode returns RC_SUCCESS on
> TPM2_Startup, the field upgrade mode has to be detected by
> TPM2_GetCapability.
> 
> Signed-off-by: Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@...ineon.com>
> ---
> Changelog:
>  * v2:
>    * Move check of -ENODATA to if condition below.
>    * Change 'field upgrade mode' to lower case.
> 
>  drivers/char/tpm/tpm2-cmd.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index 04a3e23a4afc..c1eb5d223839 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -754,7 +754,11 @@ int tpm2_auto_startup(struct tpm_chip *chip)
>  	rc = tpm2_get_cc_attrs_tbl(chip);
>  
>  out:
> -	if (rc == TPM2_RC_UPGRADE) {
> +	/*
> +	 * Infineon TPM in field upgrade mode will return no data for the number
> +	 * of supported commands.
> +	 */
> +	if (rc == TPM2_RC_UPGRADE || rc == -ENODATA) {
>  		dev_info(&chip->dev, "TPM in field upgrade mode, requires firmware upgrade\n");
>  		chip->flags |= TPM_CHIP_FLAG_FIRMWARE_UPGRADE;
>  		rc = 0;
> -- 
> 2.25.1
> 

Looks good to me.

Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>

BR, Jarkko