linux-kernel - Re: [PATCH v9 4/7] remoteproc: core: Add TEE interface support for firmware release

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Message-ID: <ZvGA9741OV3aexzs@p14s>
Date: Mon, 23 Sep 2024 08:53:43 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>
Cc: Bjorn Andersson <andersson@...nel.org>,
	Jens Wiklander <jens.wiklander@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
	op-tee@...ts.trustedfirmware.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v9 4/7] remoteproc: core: Add TEE interface support for
 firmware release

On Tue, Sep 17, 2024 at 06:56:58PM +0200, Arnaud POULIQUEN wrote:
> Hello Mathieu,
> 
> On 9/12/24 17:26, Mathieu Poirier wrote:
> > On Fri, Aug 30, 2024 at 11:51:44AM +0200, Arnaud Pouliquen wrote:
> >> Add support for releasing remote processor firmware through
> >> the Trusted Execution Environment (TEE) interface.
> >>
> >> The tee_rproc_release_fw() function is called in the following cases:
> >>
> >> - An error occurs in rproc_start() between the loading of the segments and
> >>   the start of the remote processor.
> >> - When rproc_release_fw is called on error or after stopping the remote
> >>   processor.
> >>
> >> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
> >> ---
> >>  drivers/remoteproc/remoteproc_core.c | 10 ++++++++--
> >>  1 file changed, 8 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> >> index 7694817f25d4..32052dedc149 100644
> >> --- a/drivers/remoteproc/remoteproc_core.c
> >> +++ b/drivers/remoteproc/remoteproc_core.c
> >> @@ -29,6 +29,7 @@
> >>  #include <linux/debugfs.h>
> >>  #include <linux/rculist.h>
> >>  #include <linux/remoteproc.h>
> >> +#include <linux/remoteproc_tee.h>
> >>  #include <linux/iommu.h>
> >>  #include <linux/idr.h>
> >>  #include <linux/elf.h>
> >> @@ -1258,6 +1259,9 @@ static int rproc_alloc_registered_carveouts(struct rproc *rproc)
> >>  
> >>  static void rproc_release_fw(struct rproc *rproc)
> >>  {
> >> +	if (rproc->state == RPROC_OFFLINE && rproc->tee_interface)
> >> +		tee_rproc_release_fw(rproc);
> > 
> > Function tee_rproc_release_fw() returns a value that is ignored.  I don't know
> > how it passes the Sparse checker but I already see patches coming in my Inbox to
> > deal with that.  In this case there is nothing else to do if there is an error
> > releasing the firware.  As such I would put a (void) in front and add a comment
> > about the return value being ignore on purpose.
> 
> Instead of ignoring the error, I wonder if we should panic in
> tee_rproc_release_fw(). Indeed, we would be in an unexpected state without any
> possible action to return to a normal state.

Nowadays a call to panic() is only used in very dire situations and I don't see
this meeting that requirement.  I would just call a dev_err() and let it be.

> 
> Regards,
> Arnaud
> 
> > 
> >> +
> >>  	/* Free the copy of the resource table */
> >>  	kfree(rproc->cached_table);
> >>  	rproc->cached_table = NULL;
> >> @@ -1348,7 +1352,7 @@ static int rproc_start(struct rproc *rproc, const struct firmware *fw)
> >>  	if (ret) {
> >>  		dev_err(dev, "failed to prepare subdevices for %s: %d\n",
> >>  			rproc->name, ret);
> >> -		goto reset_table_ptr;
> >> +		goto release_fw;
> >>  	}
> >>  
> >>  	/* power up the remote processor */
> >> @@ -1376,7 +1380,9 @@ static int rproc_start(struct rproc *rproc, const struct firmware *fw)
> >>  	rproc->ops->stop(rproc);
> >>  unprepare_subdevices:
> >>  	rproc_unprepare_subdevices(rproc);
> >> -reset_table_ptr:
> >> +release_fw:
> >> +	if (rproc->tee_interface)
> >> +		tee_rproc_release_fw(rproc);
> > 
> > Same here.
> > 
> >>  	rproc->table_ptr = rproc->cached_table;
> >>  
> >>  	return ret;
> >> -- 
> >> 2.25.1
> >>