linux-kernel - Re: [PATCH 1/2] firmware: qcom: scm: Return -EOPNOTSUPP for unsupported SHM bridge enabling

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Message-ID: <ZwQkbqpVzMDm7iJV@hu-mojha-hyd.qualcomm.com>
Date: Mon, 7 Oct 2024 23:41:58 +0530
From: Mukesh Ojha <quic_mojha@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: Kuldeep Singh <quic_kuldsing@...cinc.com>,
        Bjorn Andersson
	<andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        "Bartosz
 Golaszewski" <bartosz.golaszewski@...aro.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Qingqing
 Zhou" <quic_qqzhou@...cinc.com>
Subject: Re: [PATCH 1/2] firmware: qcom: scm: Return -EOPNOTSUPP for
 unsupported SHM bridge enabling

On Sun, Oct 06, 2024 at 08:35:57PM +0300, Dmitry Baryshkov wrote:
> On Sat, Oct 05, 2024 at 07:31:49PM GMT, Kuldeep Singh wrote:
> > From: Qingqing Zhou <quic_qqzhou@...cinc.com>
> > 
> > Currently for enabling shm bridge, QTEE will return 0 and put error 4 into
> > result[0] to qcom_scm for unsupported platform, tzmem will consider this
> > as an unknown error not the unsupported case on the platform.
> > 
> > Error log:
> > [    0.177224] qcom_scm firmware:scm: error (____ptrval____): Failed to enable the TrustZone memory allocator
> > [    0.177244] qcom_scm firmware:scm: probe with driver qcom_scm failed with error 4
> > 
> > Change the function call qcom_scm_shm_bridge_enable() to remap this
> > result[0] into the unsupported error and then tzmem can consider this as
> > unsupported case instead of reporting an error.
> > 
> > Signed-off-by: Qingqing Zhou <quic_qqzhou@...cinc.com>
> > Co-developed-by: Kuldeep Singh <quic_kuldsing@...cinc.com>
> > Signed-off-by: Kuldeep Singh <quic_kuldsing@...cinc.com>
> > ---
> >  drivers/firmware/qcom/qcom_scm.c | 12 +++++++++++-
> >  1 file changed, 11 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> > index 10986cb11ec0..620313359042 100644
> > --- a/drivers/firmware/qcom/qcom_scm.c
> > +++ b/drivers/firmware/qcom/qcom_scm.c
> > @@ -111,6 +111,10 @@ enum qcom_scm_qseecom_tz_cmd_info {
> >  	QSEECOM_TZ_CMD_INFO_VERSION		= 3,
> >  };
> >  
> > +enum qcom_scm_shm_bridge_result {
> > +	SHMBRIDGE_RESULT_NOTSUPP	= 4,
> > +};
> > +
> >  #define QSEECOM_MAX_APP_NAME_SIZE		64
> >  
> >  /* Each bit configures cold/warm boot address for one of the 4 CPUs */
> > @@ -1361,6 +1365,8 @@ EXPORT_SYMBOL_GPL(qcom_scm_lmh_dcvsh_available);
> >  
> >  int qcom_scm_shm_bridge_enable(void)
> >  {
> > +	int ret;
> > +
> >  	struct qcom_scm_desc desc = {
> >  		.svc = QCOM_SCM_SVC_MP,
> >  		.cmd = QCOM_SCM_MP_SHM_BRIDGE_ENABLE,
> > @@ -1373,7 +1379,11 @@ int qcom_scm_shm_bridge_enable(void)
> >  					  QCOM_SCM_MP_SHM_BRIDGE_ENABLE))
> >  		return -EOPNOTSUPP;
> >  
> > -	return qcom_scm_call(__scm->dev, &desc, &res) ?: res.result[0];
> > +	ret = qcom_scm_call(__scm->dev, &desc, &res);
> > +	if (!ret && res.result[0] == SHMBRIDGE_RESULT_NOTSUPP)
> > +		return -EOPNOTSUPP;
> > +
> > +	return ret ?: res.result[0];
> 
> Could you please make it less cryptic?
> 
> if (ret)
> 	return ret;
> 
> if (res.result[0] == SHMBRIDGE_RESULT_NOTSUPP)
> 	return -EOPNOTSUPP;
> 
> return res.result[0];

Ack. for this.

-Mukesh
> 
> >  }
> >  EXPORT_SYMBOL_GPL(qcom_scm_shm_bridge_enable);
> >  
> > -- 
> > 2.34.1
> > 
> 
> -- 
> With best wishes
> Dmitry
>