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

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Date: Thu, 23 May 2024 20:35:59 +0200
From: Sascha Hauer <s.hauer@...gutronix.de>
To: Pankaj Gupta <pankaj.gupta@....com>
Cc: Jonathan Corbet <corbet@....net>, Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [EXT] Re: [PATCH v2 4/5] firmware: imx: add driver for NXP
 EdgeLock Enclave

On Thu, May 23, 2024 at 01:43:46PM +0000, Pankaj Gupta wrote:
> 
> 
> > -----Original Message-----
> > From: Sascha Hauer <s.hauer@...gutronix.de>
> > Sent: Thursday, May 23, 2024 6:54 PM
> > To: Pankaj Gupta <pankaj.gupta@....com>
> > Cc: Jonathan Corbet <corbet@....net>; Rob Herring <robh+dt@...nel.org>;
> > Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>; Conor Dooley
> > <conor+dt@...nel.org>; Shawn Guo <shawnguo@...nel.org>; Pengutronix
> > Kernel Team <kernel@...gutronix.de>; Fabio Estevam
> > <festevam@...il.com>; Rob Herring <robh@...nel.org>; Krzysztof Kozlowski
> > <krzk+dt@...nel.org>; linux-doc@...r.kernel.org; linux-
> > kernel@...r.kernel.org; devicetree@...r.kernel.org; imx@...ts.linux.dev;
> > linux-arm-kernel@...ts.infradead.org
> > Subject: [EXT] Re: [PATCH v2 4/5] firmware: imx: add driver for NXP EdgeLock
> > Enclave
> >
> > Caution: This is an external email. Please take care when clicking links or
> > opening attachments. When in doubt, report the message using the 'Report
> > this email' button
> >
> >
> > 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@....com>
> > > ---
> > >  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.

You take the lock and release it immediately afterwards. There's nothing
locked with this. Please have a look how scoped_guard() works.

Sascha

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