linux-kernel - Re: [PATCH v9 2/4] tpm: of: Make of-tree specific function commonly available

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Message-ID: <e4dcxwp63uisirxwanjwrhzrnve45wqnxhijfp4oq274r4neco@v2btoy43ue5h>
Date:   Wed, 24 May 2023 15:56:37 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Stefan Berger <stefanb@...ux.ibm.com>
Cc:     kexec@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, nayna@...ux.ibm.com,
        nasastry@...ibm.com, mpe@...erman.id.au,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Nageswara R Sastry <rnsastry@...ux.ibm.com>,
        Coiby Xu <coxu@...hat.com>
Subject: Re: [PATCH v9 2/4] tpm: of: Make of-tree specific function commonly
 available

On Tue, Apr 18, 2023 at 09:44:07AM -0400, Stefan Berger wrote:
> Simplify tpm_read_log_of() by moving reusable parts of the code into
> an inline function that makes it commonly available so it can be
> used also for kexec support. Call the new of_tpm_get_sml_parameters()
> function from the TPM Open Firmware driver.
> 
> Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
> Cc: Jarkko Sakkinen <jarkko@...nel.org>
> Cc: Jason Gunthorpe <jgg@...pe.ca>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Frank Rowand <frowand.list@...il.com>
> Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
> Tested-by: Nageswara R Sastry <rnsastry@...ux.ibm.com>
> Tested-by: Coiby Xu <coxu@...hat.com>
> Acked-by: Jarkko Sakkinen <jarkko@...nel.org>
> 

Reviewed-by: Jerry Snitselaar <jsnitsel@...hat.com>

> ---
> v9:
>  - Rebased on 6.3-rc7; call tpm_read_log_memory_region if -ENODEV returned
> 
> v7:
>  - Added original comment back into inlined function
> 
> v4:
>  - converted to inline function
> ---
>  drivers/char/tpm/eventlog/of.c | 30 +++++-----------------------
>  include/linux/tpm.h            | 36 ++++++++++++++++++++++++++++++++++
>  2 files changed, 41 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
> index 930fe43d5daf..41688d9cbd3b 100644
> --- a/drivers/char/tpm/eventlog/of.c
> +++ b/drivers/char/tpm/eventlog/of.c
> @@ -51,11 +51,10 @@ static int tpm_read_log_memory_region(struct tpm_chip *chip)
>  int tpm_read_log_of(struct tpm_chip *chip)
>  {
>  	struct device_node *np;
> -	const u32 *sizep;
> -	const u64 *basep;
>  	struct tpm_bios_log *log;
>  	u32 size;
>  	u64 base;
> +	int ret;
>  
>  	log = &chip->log;
>  	if (chip->dev.parent && chip->dev.parent->of_node)
> @@ -66,30 +65,11 @@ int tpm_read_log_of(struct tpm_chip *chip)
>  	if (of_property_read_bool(np, "powered-while-suspended"))
>  		chip->flags |= TPM_CHIP_FLAG_ALWAYS_POWERED;
>  
> -	sizep = of_get_property(np, "linux,sml-size", NULL);
> -	basep = of_get_property(np, "linux,sml-base", NULL);
> -	if (sizep == NULL && basep == NULL)
> +	ret = of_tpm_get_sml_parameters(np, &base, &size);
> +	if (ret == -ENODEV)
>  		return tpm_read_log_memory_region(chip);
> -	if (sizep == NULL || basep == NULL)
> -		return -EIO;
> -
> -	/*
> -	 * 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 &&
> -	    of_property_match_string(np, "compatible", "IBM,vtpm20") < 0) {
> -		size = be32_to_cpup((__force __be32 *)sizep);
> -		base = be64_to_cpup((__force __be64 *)basep);
> -	} else {
> -		size = *sizep;
> -		base = *basep;
> -	}
> +	if (ret < 0)
> +		return ret;
>  
>  	if (size == 0) {
>  		dev_warn(&chip->dev, "%s: Event log area empty\n", __func__);
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index 4dc97b9f65fb..dd9a376a1dbb 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -461,4 +461,40 @@ static inline struct tpm_chip *tpm_default_chip(void)
>  	return NULL;
>  }
>  #endif
> +
> +#ifdef CONFIG_OF
> +static inline int of_tpm_get_sml_parameters(struct device_node *np,
> +					    u64 *base, u32 *size)
> +{
> +	const u32 *sizep;
> +	const u64 *basep;
> +
> +	sizep = of_get_property(np, "linux,sml-size", NULL);
> +	basep = of_get_property(np, "linux,sml-base", NULL);
> +	if (sizep == NULL && basep == NULL)
> +		return -ENODEV;
> +	if (sizep == NULL || basep == NULL)
> +		return -EIO;
> +
> +	/*
> +	 * 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 &&
> +	    of_property_match_string(np, "compatible", "IBM,vtpm20") < 0) {
> +		*size = be32_to_cpup((__force __be32 *)sizep);
> +		*base = be64_to_cpup((__force __be64 *)basep);
> +	} else {
> +		*size = *sizep;
> +		*base = *basep;
> +	}
> +	return 0;
> +}
> +#endif
> +
>  #endif
> -- 
> 2.38.1
>