Re: [PATCH v7 1/2] tpm: enhance read_log_of() to support Physical TPM event log

[Jarkko Sakkinen]

On Sun, Dec 11, 2016 at 12:35:32AM -0500, Nayna Jain wrote:
> Physical TPMs use Open Firmware Device Tree bindings that are similar
> to the IBM Power virtual TPM to support event log. However, these
> properties store the values in different endianness for Physical
> and Virtual TPM.
> 
> This patch fixes the endianness issue by doing appropriate conversion
> based on Physical or Virtual TPM.

Will other device tree using firmwares than OF use the same bindings?

> Signed-off-by: Nayna Jain <nayna@xxxxxxxxxxxxxxxxxx>
> ---
>  drivers/char/tpm/tpm_of.c | 27 +++++++++++++++++++++++----
>  1 file changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
> index 7dee42d7..de57d4a 100644
> --- a/drivers/char/tpm/tpm_of.c
> +++ b/drivers/char/tpm/tpm_of.c
> @@ -27,6 +27,8 @@ int tpm_read_log_of(struct tpm_chip *chip)
>  	const u32 *sizep;
>  	const u64 *basep;
>  	struct tpm_bios_log *log;
> +	u32 size;
> +	u64 base;
>  
>  	log = &chip->log;
>  	if (chip->dev.parent && chip->dev.parent->of_node)
> @@ -41,18 +43,35 @@ int tpm_read_log_of(struct tpm_chip *chip)
>  	if (sizep == NULL || basep == NULL)
>  		return -EIO;
>  
> -	if (*sizep == 0) {
> +	/*
> +	 * For both vtpm/tpm, firmware has log addr and log size in big
> +	 * endian format. But in case of vtpm, there is a method called
> +	 * sml-handover which is run during kernel init even before
> +	 * device tree is setup. This sml-handover function takes care
> +	 * of endianness and writes to sml-base and sml-size in little
> +	 * endian format. For this reason, vtpm doesn't need conversion
> +	 * but physical tpm needs the conversion.
> +	 */
> +	if (of_property_match_string(np, "compatible", "IBM,vtpm") < 0) {
> +		size = be32_to_cpup(sizep);
> +		base = be64_to_cpup(basep);
> +	} else {
> +		size = *sizep;
> +		base = *basep;
> +	}
> +
> +	if (size == 0) {
>  		dev_warn(&chip->dev, "%s: Event log area empty\n", __func__);
>  		return -EIO;
>  	}
>  
> -	log->bios_event_log = kmalloc(*sizep, GFP_KERNEL);
> +	log->bios_event_log = kmalloc(size, GFP_KERNEL);
>  	if (!log->bios_event_log)
>  		return -ENOMEM;
>  
> -	log->bios_event_log_end = log->bios_event_log + *sizep;
> +	log->bios_event_log_end = log->bios_event_log + size;
>  
> -	memcpy(log->bios_event_log, __va(*basep), *sizep);
> +	memcpy(log->bios_event_log, __va(base), size);
>  
>  	return 0;
>  }
> -- 
> 2.5.0
> 

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>

/Jarkko