linux-kernel - [PATCH v3] firmware: qcom: scm: Return -EOPNOTSUPP for unsupported SHM bridge enabling

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Message-ID: <20241022192148.1626633-1-quic_kuldsing@quicinc.com>
Date: Wed, 23 Oct 2024 00:51:48 +0530
From: Kuldeep Singh <quic_kuldsing@...cinc.com>
To: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio
	<konradybcio@...nel.org>,
        Bartosz Golaszewski
	<bartosz.golaszewski@...aro.org>
CC: <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Qingqing
 Zhou" <quic_qqzhou@...cinc.com>,
        Mukesh Ojha <quic_mojha@...cinc.com>
Subject: [PATCH v3] firmware: qcom: scm: Return -EOPNOTSUPP for unsupported SHM bridge enabling

From: Qingqing Zhou <quic_qqzhou@...cinc.com>

When enabling SHM bridge, QTEE returns 0 and sets error 4 in result to
qcom_scm for unsupported platforms. Currently, tzmem interprets this as
an unknown error rather than recognizing it as an unsupported 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

To address this, modify the function call qcom_scm_shm_bridge_enable()
to remap result to indicate an unsupported error. This way, tzmem will
correctly identify it as an unsupported platform case instead of
reporting it as an error.

Fixes: 178e19c0df1b ("firmware: qcom: scm: add support for SHM bridge operations")
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>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Reviewed-by: Mukesh Ojha <quic_mojha@...cinc.com>
---
v3:
- Split patch series as it's a fix and required for other dependent patches.
v2:
- Link: https://lore.kernel.org/linux-arm-msm/20241014111527.2272428-1-quic_kuldsing@quicinc.com/
v1:
- Link: https://lore.kernel.org/linux-arm-msm/20241005140150.4109700-1-quic_kuldsing@quicinc.com/
 
 drivers/firmware/qcom/qcom_scm.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index fba3ac676d1d..478538604225 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -112,6 +112,7 @@ enum qcom_scm_qseecom_tz_cmd_info {
 };
 
 #define QSEECOM_MAX_APP_NAME_SIZE		64
+#define SHMBRIDGE_RESULT_NOTSUPP		4
 
 /* Each bit configures cold/warm boot address for one of the 4 CPUs */
 static const u8 qcom_scm_cpu_cold_bits[QCOM_SCM_BOOT_MAX_CPUS] = {
@@ -1361,6 +1362,8 @@ 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 +1376,15 @@ 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)
+		return ret;
+
+	if (res.result[0] == SHMBRIDGE_RESULT_NOTSUPP)
+		return -EOPNOTSUPP;
+
+	return res.result[0];
 }
 EXPORT_SYMBOL_GPL(qcom_scm_shm_bridge_enable);
 
-- 
2.34.1