linux-kernel - Re: [PATCH v6 09/17] soc: qcom: ice: add HWKM support to the ICE driver

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Message-ID: <7uoq72bpiqmo2olwpnudpv3gtcowpnd6jrifff34ubmfpijgc6@k6rmnalu5z4o>
Date: Sat, 7 Sep 2024 01:07:16 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Jens Axboe <axboe@...nel.dk>, Jonathan Corbet <corbet@....net>, 
	Alasdair Kergon <agk@...hat.com>, Mike Snitzer <snitzer@...nel.org>, 
	Mikulas Patocka <mpatocka@...hat.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Asutosh Das <quic_asutoshd@...cinc.com>, Ritesh Harjani <ritesh.list@...il.com>, 
	Ulf Hansson <ulf.hansson@...aro.org>, Alim Akhtar <alim.akhtar@...sung.com>, 
	Avri Altman <avri.altman@....com>, Bart Van Assche <bvanassche@....org>, 
	"James E.J. Bottomley" <James.Bottomley@...senpartnership.com>, "Martin K. Petersen" <martin.petersen@...cle.com>, 
	Eric Biggers <ebiggers@...nel.org>, "Theodore Y. Ts'o" <tytso@....edu>, 
	Jaegeuk Kim <jaegeuk@...nel.org>, Alexander Viro <viro@...iv.linux.org.uk>, 
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
	Gaurav Kashyap <quic_gaurkash@...cinc.com>, Neil Armstrong <neil.armstrong@...aro.org>, 
	linux-block@...r.kernel.org, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	dm-devel@...ts.linux.dev, linux-mmc@...r.kernel.org, linux-scsi@...r.kernel.org, 
	linux-fscrypt@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v6 09/17] soc: qcom: ice: add HWKM support to the ICE
 driver

On Fri, Sep 06, 2024 at 08:07:12PM GMT, Bartosz Golaszewski wrote:
> From: Gaurav Kashyap <quic_gaurkash@...cinc.com>
> 
> Qualcomm's ICE (Inline Crypto Engine) contains a proprietary key
> management hardware called Hardware Key Manager (HWKM). Add HWKM support
> to the ICE driver if it is available on the platform. HWKM primarily
> provides hardware wrapped key support where the ICE (storage) keys are
> not available in software and instead protected in hardware.
> 
> When HWKM software support is not fully available (from Trustzone), there
> can be a scenario where the ICE hardware supports HWKM, but it cannot be
> used for wrapped keys. In this case, raw keys have to be used without
> using the HWKM. We query the TZ at run-time to find out whether wrapped
> keys support is available.
> 
> Tested-by: Neil Armstrong <neil.armstrong@...aro.org>
> Signed-off-by: Gaurav Kashyap <quic_gaurkash@...cinc.com>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> ---
>  drivers/soc/qcom/ice.c | 152 +++++++++++++++++++++++++++++++++++++++++++++++--
>  include/soc/qcom/ice.h |   1 +
>  2 files changed, 149 insertions(+), 4 deletions(-)
> 
>  int qcom_ice_enable(struct qcom_ice *ice)
>  {
> +	int err;
> +
>  	qcom_ice_low_power_mode_enable(ice);
>  	qcom_ice_optimization_enable(ice);
>  
> -	return qcom_ice_wait_bist_status(ice);
> +	if (ice->use_hwkm)
> +		qcom_ice_enable_standard_mode(ice);
> +
> +	err = qcom_ice_wait_bist_status(ice);
> +	if (err)
> +		return err;
> +
> +	if (ice->use_hwkm)
> +		qcom_ice_hwkm_init(ice);
> +
> +	return err;
>  }
>  EXPORT_SYMBOL_GPL(qcom_ice_enable);
>  
> @@ -150,6 +282,10 @@ int qcom_ice_resume(struct qcom_ice *ice)
>  		return err;
>  	}
>  
> +	if (ice->use_hwkm) {
> +		qcom_ice_enable_standard_mode(ice);
> +		qcom_ice_hwkm_init(ice);
> +	}
>  	return qcom_ice_wait_bist_status(ice);
>  }
>  EXPORT_SYMBOL_GPL(qcom_ice_resume);
> @@ -157,6 +293,7 @@ EXPORT_SYMBOL_GPL(qcom_ice_resume);
>  int qcom_ice_suspend(struct qcom_ice *ice)
>  {
>  	clk_disable_unprepare(ice->core_clk);
> +	ice->hwkm_init_complete = false;
>  
>  	return 0;
>  }
> @@ -206,6 +343,12 @@ int qcom_ice_evict_key(struct qcom_ice *ice, int slot)
>  }
>  EXPORT_SYMBOL_GPL(qcom_ice_evict_key);
>  
> +bool qcom_ice_hwkm_supported(struct qcom_ice *ice)
> +{
> +	return ice->use_hwkm;
> +}
> +EXPORT_SYMBOL_GPL(qcom_ice_hwkm_supported);
> +
>  static struct qcom_ice *qcom_ice_create(struct device *dev,
>  					void __iomem *base)
>  {
> @@ -240,6 +383,7 @@ static struct qcom_ice *qcom_ice_create(struct device *dev,
>  		engine->core_clk = devm_clk_get_enabled(dev, NULL);
>  	if (IS_ERR(engine->core_clk))
>  		return ERR_CAST(engine->core_clk);
> +	engine->use_hwkm = qcom_scm_has_wrapped_key_support();

This still makes the decision on whether to use HW-wrapped keys on
behalf of a user. I suppose this is incorrect. The user must be able to
use raw keys even if HW-wrapped keys are available on the platform. One
of the examples for such use-cases is if a user prefers to be able to
recover stored information in case of a device failure (such recovery
will be impossible if SoC is damaged and HW-wrapped keys are used).

>  
>  	if (!qcom_ice_check_supported(engine))
>  		return ERR_PTR(-EOPNOTSUPP);
> diff --git a/include/soc/qcom/ice.h b/include/soc/qcom/ice.h
> index 9dd835dba2a7..1f52e82e3e1c 100644
> --- a/include/soc/qcom/ice.h
> +++ b/include/soc/qcom/ice.h
> @@ -34,5 +34,6 @@ int qcom_ice_program_key(struct qcom_ice *ice,
>  			 const struct blk_crypto_key *bkey,
>  			 u8 data_unit_size, int slot);
>  int qcom_ice_evict_key(struct qcom_ice *ice, int slot);
> +bool qcom_ice_hwkm_supported(struct qcom_ice *ice);
>  struct qcom_ice *of_qcom_ice_get(struct device *dev);
>  #endif /* __QCOM_ICE_H__ */
> 
> -- 
> 2.43.0
> 

-- 
With best wishes
Dmitry