On 10/7/2024 7:10 AM, Bjorn Andersson wrote:
> On Sat, Oct 05, 2024 at 07:31:49PM GMT, Kuldeep Singh wrote:
>
> Please shorten the subject a bit, perhaps:
> "firmware: qcom: scm: Improve unsupported SHM bridge detection"
>
>> From: Qingqing Zhou <quic_qqzhou@xxxxxxxxxxx>
>>
>> Currently for enabling shm bridge, QTEE will return 0 and put error 4 into
>
> s/for/when/
Ack.
>
>> 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.
>>
>
> Sounds like we want a Fixes tag here.
Ack.
>
>> Signed-off-by: Qingqing Zhou <quic_qqzhou@xxxxxxxxxxx>
>> Co-developed-by: Kuldeep Singh <quic_kuldsing@xxxxxxxxxxx>
>> Signed-off-by: Kuldeep Singh <quic_kuldsing@xxxxxxxxxxx>
>> ---
>> 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,
>> +};
>
> This is not an enumeration, but a fixed defined constant. Please use
> #define.
Ack.
>> +
>> #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];
>
> I'd prefer, with the additional check, that you'd structure it like this:
>
> if (ret)
> return ret;
>
> if (res.result[0] == SHMBRIDGE_RESULT_NOTSUPP)
> return -EOPNOTSUPP;
>
> return res.result[0];
Sure, above looks more cleaner. Will update in next rev.
>
> That way we deal with SCM-call errors first, otherwise we inspect and
> act on the returned data.
>
> That said, the return value of this function, if non-zero, will trickle
> back to and be returned from qcom_scm_probe(), where Linux expects to
> see a valid error code. Are there any other result[0] values we should
> handle, which would allow us to end this function with "return 0"?
As qcom_scm_shm_bridge_enable() is an shm enablement call, need to handle
supported(or unsupported) scenario appropriately and other errors can be
propagated to qcom_tzmem/qcom_scm_probe.
Please note, other return values(related to access control) from QTEE are
failures and do not require conversion to Linux error codes.
--
Regards
Kuldeep
