Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Mime-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset=UTF-8
Date:   Thu, 03 Aug 2023 12:01:59 +0300
Message-Id: <CUISDE4L54JX.2KYPM33L74XRT@suppilovahvero>
To:     "Mario Limonciello" <mario.limonciello@amd.com>,
        <peterhuewe@gmx.de>
Cc:     <linux-kernel@vger.kernel.org>, <linux-integrity@vger.kernel.org>,
        <Jason@zx2c4.com>, <dragonn@op.pl>
Subject: Re: [PATCH 3/3] tpm: Drop CONFIG_HW_RANDOM_TPM
From:   "Jarkko Sakkinen" <jarkko@kernel.org>
References: <20230803015015.915-1-mario.limonciello@amd.com>
 <20230803015015.915-4-mario.limonciello@amd.com>
In-Reply-To: <20230803015015.915-4-mario.limonciello@amd.com>
Precedence: bulk

On Thu Aug 3, 2023 at 4:50 AM EEST, Mario Limonciello wrote:
> As the behavior of whether a TPM is registered for hwrng can be controlle=
d
> by command line, drop the kernel configuration option.
>
> Cc: Mateusz Schyboll <dragonn@op.pl>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
>  drivers/char/tpm/Kconfig    | 11 -----------
>  drivers/char/tpm/tpm-chip.c |  6 +++---
>  2 files changed, 3 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> index 927088b2c3d3f..69aaa730dc208 100644
> --- a/drivers/char/tpm/Kconfig
> +++ b/drivers/char/tpm/Kconfig
> @@ -27,17 +27,6 @@ menuconfig TCG_TPM
> =20
>  if TCG_TPM
> =20
> -config HW_RANDOM_TPM
> -	bool "TPM HW Random Number Generator support"
> -	depends on TCG_TPM && HW_RANDOM && !(TCG_TPM=3Dy && HW_RANDOM=3Dm)
> -	default y
> -	help
> -	  This setting exposes the TPM's Random Number Generator as a hwrng
> -	  device. This allows the kernel to collect randomness from the TPM at
> -	  boot, and provides the TPM randomines in /dev/hwrng.
> -
> -	  If unsure, say Y.
> -
>  config TCG_TIS_CORE
>  	tristate
>  	help
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 8fb42232bd7a5..0d69335743469 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -533,7 +533,7 @@ static int tpm_add_hwrng(struct tpm_chip *chip)
>  	if (!trust_tpm)
>  		chip->flags |=3D TPM_CHIP_FLAG_HWRNG_DISABLED;
> =20
> -	if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM) || tpm_is_firmware_upgrade(chip) =
||
> +	if (tpm_is_firmware_upgrade(chip) ||
>  	    chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED)
>  		return 0;
> =20
> @@ -639,7 +639,7 @@ int tpm_chip_register(struct tpm_chip *chip)
>  	return 0;
> =20
>  out_hwrng:
> -	if (IS_ENABLED(CONFIG_HW_RANDOM_TPM) && !tpm_is_firmware_upgrade(chip) =
&&
> +	if (!tpm_is_firmware_upgrade(chip) &&
>  	    !(chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED))
>  		hwrng_unregister(&chip->hwrng);
>  out_ppi:
> @@ -665,7 +665,7 @@ EXPORT_SYMBOL_GPL(tpm_chip_register);
>  void tpm_chip_unregister(struct tpm_chip *chip)
>  {
>  	tpm_del_legacy_sysfs(chip);
> -	if (IS_ENABLED(CONFIG_HW_RANDOM_TPM) && !tpm_is_firmware_upgrade(chip) =
&&
> +	if (!tpm_is_firmware_upgrade(chip) &&
>  	    !(chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED))
>  		hwrng_unregister(&chip->hwrng);
>  	tpm_bios_log_teardown(chip);
> --=20
> 2.34.1

I don't understand this but please take it a way from patch set, which
should only contain critical fixes, which this definitely is not.

BR, Jarkko