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

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Message-ID: <fce2374e-384f-4005-b882-3e0d26897fb7@foss.st.com>
Date: Tue, 17 Sep 2024 18:56:58 +0200
From: Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>
To: Mathieu Poirier <mathieu.poirier@...aro.org>
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

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.

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
>>