Re: [PATCH v5 04/15] soc: qcom: ice: add hwkm support in ice

[neil.armstrong@linaro.org]

On 17/06/2024 02:50, Gaurav Kashyap wrote:
> Qualcomm's ICE (Inline Crypto Engine) contains a proprietary
> key management hardware called Hardware Key Manager (HWKM).
> This patch integrates HWKM support in ICE when it is
> available. HWKM primarily provides hardware wrapped key support
> where the ICE (storage) keys are not available in software and
> 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, standard keys have
> to be used without using HWKM. Hence, providing a toggle controlled
> by a devicetree entry to use HWKM or not.
> 
> Tested-by: Neil Armstrong <neil.armstrong@linaro.org>
> Signed-off-by: Gaurav Kashyap <quic_gaurkash@quicinc.com>
> ---
>   drivers/soc/qcom/ice.c | 153 +++++++++++++++++++++++++++++++++++++++--
>   include/soc/qcom/ice.h |   1 +
>   2 files changed, 150 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/soc/qcom/ice.c b/drivers/soc/qcom/ice.c
> index 6f941d32fffb..d5e74cf2946b 100644
> --- a/drivers/soc/qcom/ice.c
> +++ b/drivers/soc/qcom/ice.c
> @@ -26,6 +26,40 @@

<snip>

> +
>   static struct qcom_ice *qcom_ice_create(struct device *dev,
>   					void __iomem *base)
>   {
> @@ -239,6 +382,8 @@ 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 = of_property_read_bool(dev->of_node,
> +						 "qcom,ice-use-hwkm");

Please drop this property and instead add an scm function calling:

__qcom_scm_is_call_available(QCOM_SCM_SVC_ES, QCOM_SCM_ES_DERIVE_SW_SECRET)

like

bool qcom_scm_derive_sw_secret_available(void)
{
	if (!__qcom_scm_is_call_available(__scm->dev, QCOM_SCM_SVC_ES,
					  QCOM_SCM_ES_DERIVE_SW_SECRET))
		return false;

	return true;
}

You may perhaps only call qcom_scm_derive_sw_secret_available() for some
ICE versions.

Neil

>   
>   	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__ */