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Message-ID: <6594f69e-f4ba-4d2b-a3d6-7eb5c8f95ac4@quicinc.com>
Date: Tue, 18 Feb 2025 10:36:27 +1100
From: Amirreza Zarrabi <quic_azarrabi@...cinc.com>
To: Jens Wiklander <jens.wiklander@...aro.org>
CC: Sumit Garg <sumit.garg@...aro.org>,
Bjorn Andersson
<andersson@...nel.org>,
Konrad Dybcio <konradybcio@...nel.org>, Rob Herring
<robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley
<conor+dt@...nel.org>,
Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
<linux-arm-msm@...r.kernel.org>, <op-tee@...ts.trustedfirmware.org>,
<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-doc@...r.kernel.org>
Subject: Re: [PATCH v2 2/8] tee: add close_context to TEE driver operation
On 2/17/2025 8:35 PM, Jens Wiklander wrote:
> Hi,
>
> On Sun, Feb 02, 2025 at 06:43:30PM -0800, Amirreza Zarrabi wrote:
>> The tee_context can be used to manage TEE user resources, including
>> those allocated by the driver for the TEE on behalf of the user.
>> The release() callback is invoked only when all resources, such as
>> tee_shm, are released and there are no references to the tee_context.
>>
>> When a user closes the device file, the driver should notify the
>> TEE to release any resources it may hold and drop the context
>> references. To achieve this, a close_context() callback is
>> introduced to initiate resource release in the TEE driver when
>> the device file is closed.
>>
>> Relocate teedev_ctx_get, teedev_ctx_put, tee_device_get, and
>> tee_device_get functions to tee_drv.h to make them accessible
>> outside the TEE subsystem.
>>
>> Signed-off-by: Amirreza Zarrabi <quic_azarrabi@...cinc.com>
>> ---
>> drivers/tee/tee_core.c | 7 +++++++
>> drivers/tee/tee_private.h | 6 ------
>> include/linux/tee_core.h | 11 +++++++++--
>> include/linux/tee_drv.h | 6 ++++++
>> 4 files changed, 22 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
>> index 24edce4cdbaa..721522fe5c63 100644
>> --- a/drivers/tee/tee_core.c
>> +++ b/drivers/tee/tee_core.c
>> @@ -79,6 +79,7 @@ void teedev_ctx_get(struct tee_context *ctx)
>>
>> kref_get(&ctx->refcount);
>> }
>> +EXPORT_SYMBOL_GPL(teedev_ctx_get);
>>
>> static void teedev_ctx_release(struct kref *ref)
>> {
>> @@ -96,11 +97,15 @@ void teedev_ctx_put(struct tee_context *ctx)
>>
>> kref_put(&ctx->refcount, teedev_ctx_release);
>> }
>> +EXPORT_SYMBOL_GPL(teedev_ctx_put);
>>
>> void teedev_close_context(struct tee_context *ctx)
>> {
>> struct tee_device *teedev = ctx->teedev;
>>
>> + if (teedev->desc->ops->close_context)
>> + teedev->desc->ops->close_context(ctx);
>> +
>> teedev_ctx_put(ctx);
>> tee_device_put(teedev);
>> }
>> @@ -1037,6 +1042,7 @@ void tee_device_put(struct tee_device *teedev)
>> }
>> mutex_unlock(&teedev->mutex);
>> }
>> +EXPORT_SYMBOL_GPL(tee_device_put);
>>
>> bool tee_device_get(struct tee_device *teedev)
>> {
>> @@ -1049,6 +1055,7 @@ bool tee_device_get(struct tee_device *teedev)
>> mutex_unlock(&teedev->mutex);
>> return true;
>> }
>> +EXPORT_SYMBOL_GPL(tee_device_get);
>>
>> /**
>> * tee_device_unregister() - Removes a TEE device
>> diff --git a/drivers/tee/tee_private.h b/drivers/tee/tee_private.h
>> index 9bc50605227c..d3f40a03de36 100644
>> --- a/drivers/tee/tee_private.h
>> +++ b/drivers/tee/tee_private.h
>> @@ -14,12 +14,6 @@
>>
>> int tee_shm_get_fd(struct tee_shm *shm);
>>
>> -bool tee_device_get(struct tee_device *teedev);
>> -void tee_device_put(struct tee_device *teedev);
>> -
>> -void teedev_ctx_get(struct tee_context *ctx);
>> -void teedev_ctx_put(struct tee_context *ctx);
>> -
>> struct tee_shm *tee_shm_alloc_user_buf(struct tee_context *ctx, size_t size);
>> struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx,
>> unsigned long addr, size_t length);
>> diff --git a/include/linux/tee_core.h b/include/linux/tee_core.h
>> index a38494d6b5f4..8a4c9e30b652 100644
>> --- a/include/linux/tee_core.h
>> +++ b/include/linux/tee_core.h
>> @@ -65,8 +65,9 @@ struct tee_device {
>> /**
>> * struct tee_driver_ops - driver operations vtable
>> * @get_version: returns version of driver
>> - * @open: called when the device file is opened
>> - * @release: release this open file
>> + * @open: called for a context when the device file is opened
>> + * @close_context: called when the device file is closed
>> + * @release: called to release the context
>> * @open_session: open a new session
>> * @close_session: close a session
>> * @system_session: declare session as a system session
>> @@ -76,11 +77,17 @@ struct tee_device {
>> * @supp_send: called for supplicant to send a response
>> * @shm_register: register shared memory buffer in TEE
>> * @shm_unregister: unregister shared memory buffer in TEE
>> + *
>> + * The context given to @open might last longer than the device file if it is
>> + * tied to other resources in the TEE driver. @close_context is called when the
>> + * client closes the device file, even if there are existing references to the
>> + * context. The TEE driver can use @close_context to start cleaning up.
>> */
>> struct tee_driver_ops {
>> void (*get_version)(struct tee_device *teedev,
>> struct tee_ioctl_version_data *vers);
>> int (*open)(struct tee_context *ctx);
>> + void (*close_context)(struct tee_context *ctx);
>> void (*release)(struct tee_context *ctx);
>> int (*open_session)(struct tee_context *ctx,
>> struct tee_ioctl_open_session_arg *arg,
>> diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
>> index a54c203000ed..d5f0c70ac95c 100644
>> --- a/include/linux/tee_drv.h
>> +++ b/include/linux/tee_drv.h
>> @@ -96,6 +96,12 @@ struct tee_param {
>> } u;
>> };
>>
>> +bool tee_device_get(struct tee_device *teedev);
>> +void tee_device_put(struct tee_device *teedev);
>> +
>> +void teedev_ctx_get(struct tee_context *ctx);
>> +void teedev_ctx_put(struct tee_context *ctx);
>> +
>
> Now that these functions are available to all the backend drivers,
> please add some documentation for them so it more clear how they are
> supposed to be used.
>
> Thanks,
> Jens
Ack.
>
>> /**
>> * tee_shm_alloc_kernel_buf() - Allocate kernel shared memory for a
>> * particular TEE client driver
>>
>> --
>> 2.34.1
>>
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