linux-kernel - Re: [PATCH v12 16/19] tpm, tpm_tis: Allow locality to be set to a different value

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Message-ID: <Z8qbPvCdhlVzkK1H@kernel.org>
Date: Fri, 7 Mar 2025 09:07:42 +0200
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Ross Philipson <ross.philipson@...cle.com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org,
	linux-integrity@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-crypto@...r.kernel.org, kexec@...ts.infradead.org,
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	dpsmith@...rtussolutions.com, tglx@...utronix.de, mingo@...hat.com,
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	baolu.lu@...ux.intel.com, kanth.ghatraju@...cle.com,
	andrew.cooper3@...rix.com, trenchboot-devel@...glegroups.com
Subject: Re: [PATCH v12 16/19] tpm, tpm_tis: Allow locality to be set to a
 different value

On Thu, Dec 19, 2024 at 11:42:13AM -0800, Ross Philipson wrote:
> DRTM needs to be able to set the locality used by kernel. Provide
> a one-shot function tpm_chip_set_locality() for the purpose.
> 
> Signed-off-by: Ross Philipson <ross.philipson@...cle.com>
> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
> ---
>  drivers/char/tpm/tpm-chip.c     | 33 ++++++++++++++++++++++++++++++++-
>  drivers/char/tpm/tpm_tis_core.c |  2 ++
>  include/linux/tpm.h             |  4 ++++
>  3 files changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 7df7abaf3e52..ac200514c4d7 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -44,7 +44,7 @@ static int tpm_request_locality(struct tpm_chip *chip)
>  	if (!chip->ops->request_locality)
>  		return 0;
>  
> -	rc = chip->ops->request_locality(chip, 0);
> +	rc = chip->ops->request_locality(chip, chip->kernel_locality);
>  	if (rc < 0)
>  		return rc;
>  
> @@ -374,6 +374,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
>  	}
>  
>  	chip->locality = -1;
> +	chip->kernel_locality = 0;
>  	return chip;
>  
>  out:
> @@ -689,3 +690,33 @@ void tpm_chip_unregister(struct tpm_chip *chip)
>  	tpm_del_char_device(chip);
>  }
>  EXPORT_SYMBOL_GPL(tpm_chip_unregister);
> +
> +/**
> + * tpm_chip_set_locality() - Set the TPM locality kernel uses
> + * @chip:	&tpm_chip instance
> + * @locality:   new locality
> + *
> + * This a one-shot function. Returns zero or POSIX error on failure.
> + */
> +int tpm_chip_set_locality(struct tpm_chip *chip, u8 locality)
> +{
> +	int ret;
> +
> +	if (locality < 0 || locality >= TPM_MAX_LOCALITY)
> +		return -EINVAL;
> +
> +	ret = tpm_try_get_ops(chip);
> +	if (ret)
> +		return ret;
> +
> +	if (!(chip->flags & TPM_CHIP_FLAG_SET_LOCALITY_ENABLED)) {
> +		tpm_put_ops(chip);
> +		return -EINVAL;
> +	}
> +
> +	chip->kernel_locality = locality;
> +	chip->flags &= ~TPM_CHIP_FLAG_SET_LOCALITY_ENABLED;
> +	tpm_put_ops(chip);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(tpm_chip_set_locality);
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index c86100ad743a..b85677eccc86 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -1114,6 +1114,8 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
>  	if (IS_ERR(chip))
>  		return PTR_ERR(chip);
>  
> +	chip->flags |= TPM_CHIP_FLAG_SET_LOCALITY_ENABLED;
> +
>  #ifdef CONFIG_ACPI
>  	chip->acpi_dev_handle = acpi_dev_handle;
>  #endif
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index c5a4a2d7dd15..9f910d3bc2e4 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -207,6 +207,8 @@ struct tpm_chip {
>  
>  	/* active locality */
>  	int locality;
> +	/* the locality used by kernel */
> +	u8 kernel_locality;
>  
>  #ifdef CONFIG_TCG_TPM2_HMAC
>  	/* details for communication security via sessions */
> @@ -354,6 +356,7 @@ enum tpm_chip_flags {
>  	TPM_CHIP_FLAG_SUSPENDED			= BIT(8),
>  	TPM_CHIP_FLAG_HWRNG_DISABLED		= BIT(9),
>  	TPM_CHIP_FLAG_DISABLE			= BIT(10),
> +	TPM_CHIP_FLAG_SET_LOCALITY_ENABLED	= BIT(11),
>  };
>  
>  #define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)
> @@ -447,6 +450,7 @@ static inline u32 tpm2_rc_value(u32 rc)
>  extern int tpm_is_tpm2(struct tpm_chip *chip);
>  extern __must_check int tpm_try_get_ops(struct tpm_chip *chip);
>  extern void tpm_put_ops(struct tpm_chip *chip);
> +int tpm_chip_set_locality(struct tpm_chip *chip, u8 locality);
>  extern ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
>  				size_t min_rsp_body_length, const char *desc);
>  extern int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
> -- 
> 2.39.3
> 

+1 for this.

BR, Jarkko