RE: [PATCH v6 09/17] soc: qcom: ice: add HWKM support to the ICE driver

[Gaurav Kashyap (QUIC)]

On Monday, September 9, 2024 11:29 PM PDT, Dmitry Baryshkov wrote:
> On Tue, 10 Sept 2024 at 03:51, Gaurav Kashyap (QUIC)
> <quic_gaurkash@xxxxxxxxxxx> wrote:
> >
> > Hello Dmitry and Neil
> >
> > On Monday, September 9, 2024 2:44 AM PDT, Dmitry Baryshkov wrote:
> > > On Mon, Sep 09, 2024 at 10:58:30AM GMT, Neil Armstrong wrote:
> > > > On 07/09/2024 00:07, Dmitry Baryshkov wrote:
> > > > > On Fri, Sep 06, 2024 at 08:07:12PM GMT, Bartosz Golaszewski wrote:
> > > > > > From: Gaurav Kashyap <quic_gaurkash@xxxxxxxxxxx>
> > > > > >
> > > > > > 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@xxxxxxxxxx>
> > > > > > Signed-off-by: Gaurav Kashyap <quic_gaurkash@xxxxxxxxxxx>
> > > > > > Signed-off-by: Bartosz Golaszewski
> > > > > > <bartosz.golaszewski@xxxxxxxxxx>
> > > > > > ---
> > > > > >   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).
> > > >
> > > > Isn't that already the case ? the
> BLK_CRYPTO_KEY_TYPE_HW_WRAPPED
> > > size
> > > > is here to select HW-wrapped key, otherwise the ol' raw key is passed.
> > > > Just look the next patch.
> > > >
> > > > Or did I miss something ?
> > >
> > > That's a good question. If use_hwkm is set, ICE gets programmed to
> > > use hwkm (see qcom_ice_hwkm_init() call above). I'm not sure if it
> > > is expected to work properly if after such a call we pass raw key.
> > >
> >
> > Once ICE has moved to a HWKM mode, the firmware key programming
> currently does not support raw keys.
> > This support is being added for the next Qualcomm chipset in Trustzone to
> support both at he same time, but that will take another year or two to hit
> the market.
> > Until that time, due to TZ (firmware) limitations , the driver can only
> support one or the other.
> >
> > We also cannot keep moving ICE modes, due to the HWKM enablement
> being a one-time configurable value at boot.
> 
> So the init of HWKM should be delayed until the point where the user tells if
> HWKM or raw keys should be used.

Ack.
I'll work with Bartosz to look into moving to HWKM mode only during the first key program request

> 
> >
> > > >
> > > > 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__ */
> > > > > >
> > > > > > --
> > > > > > 2.43.0
> > > > > >
> > > > >
> > > >
> > >
> > > --
> > > With best wishes
> > > Dmitry
> >
> > Regards,
> > Gaurav
> 
> 
> 
> --
> With best wishes
> Dmitry

Regards,
Gaurav