RE: [EXT] Re: [PATCH v2 4/5] firmware: imx: add driver for NXP EdgeLock Enclave

[Pankaj Gupta]

> -----Original Message-----
> From: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> Sent: Thursday, May 23, 2024 6:54 PM
> To: Pankaj Gupta <pankaj.gupta@xxxxxxx>
> Cc: Jonathan Corbet <corbet@xxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>;
> Krzysztof Kozlowski <krzysztof.kozlowski+dt@xxxxxxxxxx>; Conor Dooley
> <conor+dt@xxxxxxxxxx>; Shawn Guo <shawnguo@xxxxxxxxxx>; Pengutronix
> Kernel Team <kernel@xxxxxxxxxxxxxx>; Fabio Estevam
> <festevam@xxxxxxxxx>; Rob Herring <robh@xxxxxxxxxx>; Krzysztof Kozlowski
> <krzk+dt@xxxxxxxxxx>; linux-doc@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Subject: [EXT] Re: [PATCH v2 4/5] firmware: imx: add driver for NXP EdgeLock
> Enclave
>
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> On Thu, May 23, 2024 at 04:19:35PM +0530, Pankaj Gupta wrote:
> > NXP hardware IP(s) for secure-enclaves like Edgelock Enclave(ELE), are
> > embedded in the SoC to support the features like HSM, SHE & V2X, using
> > message based communication interface.
> >
> > The secure enclave FW communicates on a dedicated messaging unit(MU)
> > based interface(s) with application core, where kernel is running.
> > It exists on specific i.MX processors. e.g. i.MX8ULP, i.MX93.
> >
> > This patch adds the driver for communication interface to
> > secure-enclave, for exchanging messages with NXP secure enclave HW
> > IP(s) like EdgeLock Enclave (ELE) from Kernel-space, used by kernel
> > management layers like
> > - DM-Crypt.
> >
> > Signed-off-by: Pankaj Gupta <pankaj.gupta@xxxxxxx>
> > ---
> >  drivers/firmware/imx/Kconfig        |  12 +
> >  drivers/firmware/imx/Makefile       |   2 +
> >  drivers/firmware/imx/ele_base_msg.c | 286 +++++++++++++++++++
> > drivers/firmware/imx/ele_base_msg.h |  92 +++++++
> >  drivers/firmware/imx/ele_common.c   | 239 ++++++++++++++++
> >  drivers/firmware/imx/ele_common.h   |  43 +++
> >  drivers/firmware/imx/se_ctrl.c      | 531
> ++++++++++++++++++++++++++++++++++++
> >  drivers/firmware/imx/se_ctrl.h      |  99 +++++++
> >  include/linux/firmware/imx/se_api.h |  14 +
> >  9 files changed, 1318 insertions(+)
>
> [...]
>
> >
> > +int imx_ele_msg_send(struct se_if_priv *priv, void *tx_msg) {
> > +     struct se_msg_hdr *header;
> > +     int err;
> > +
> > +     header = (struct se_msg_hdr *) tx_msg;
> > +
> > +     if (header->tag == priv->cmd_tag)
> > +             lockdep_assert_held(&priv->se_if_cmd_lock);
> > +
> > +     scoped_guard(mutex, &priv->se_if_lock);
>
> scoped_guard() with an empty block doesn't make much sense. Either use
> scope_guard() { /* do something locked */ }; or guard().
>
Need to allow send more than one message at a time. Hence, done it after taking the lock.
Once message sent, scope of lock is over.
Thus, scope of the lock se_if_lock, to execute the function "mbox_send_message()", keeping the "se_if_lock" locked.

> Sascha
>
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