Re: [PATCH v2 0/6] Add TEE based client driver for UEFI Secure Application

[Harshal Dev]

Hi Dmitry,

Gentle reminder. I am hoping we are aligned now.

Overall QSEECOM can be a separate effort for supporting older devices without
SMCInvoke/QCOMTEE support. By moving forward with this series and with a separate
one for QSEECOM, we will be able to support EFI variables on all Qualcomm platforms
supported upstream.

Regards,
Harshal

On 02-09-2026 01:41 pm, Harshal Dev wrote:
> Hi Dmitry,
> 
> On 29-08-2026 08:19 pm, Dmitry Baryshkov wrote:
>> On Wed, Aug 12, 2026 at 05:00:27PM +0530, Harshal Dev via OP-TEE wrote:
>>> Hi Dmitry,
>>
>> Hi Harshal, please excuse the huge delay from my side, I was on vacation
>> and then burried under the rest of the issues.
>>
> 
> Ahh I was not aware, I hope you had a good vacation Dmitry.
>>>
>>> On 10-08-2026 12:37 pm, Dmitry Baryshkov wrote:
>>>> On Fri, Jul 24, 2026 at 02:43:42PM +0530, Harshal Dev wrote:
>>>>> Hi Dmitry,
>>>>>
>>>>> On 22-07-2026 01:56 pm, Dmitry Baryshkov wrote:
>>>>>> On Wed, Jul 22, 2026 at 12:29:11PM +0530, Harshal Dev wrote:
>>>>>>> On Qualcomm SoC based platforms, UEFI stores EFI variables within the
>>>>>>> Replay Protected Memory Block (RPMB) which is only accessible by the
>>>>>>> Qualcomm Trusted Execution Environment (QTEE).
>>>>>>
>>>>>> Is it so? I think RPMB is accessible to Linux...
>>>>>
>>>>> I should have been more descriptive here, RPMB is accessible by Linux but
>>>>> its frames can only be prepared by QTEE.
>>>>>
>>>>> The RPMB key which is one-time programmed into the storage controller to allow
>>>>> authentication of the RPMB frames is generated by and only available to a TEE.
>>>>> So on Qualcomm platforms (and many others platforms with a TEE) Linux can only
>>>>> route the RPMB frames generated by QTEE to the storage, it cannot create and
>>>>> write the RPMB frames itself (it doesn't have access to the key).
>>>>>
>>>>> While it is possible for Linux to generate/program/store this key, on Qualcomm
>>>>> platforms we do not want Linux to do so because we do not trust it. We trust
>>>>> QTEE.
>>>>>
>>>>> I will re-phrase this and make it a bit more clear everywhere.
>>>>
>>>> OK.
>>>>
>>>>>
>>>>>>
>>>>>>> For Qualcomm platforms without emulated RPMB support, specifically
>>>>>>
>>>>>> What is emulated RPMB support? Why is it mentioned here? Which platforms
>>>>>> use emulated RPMB?
>>>>>
>>>>> Emulated RPMB refers to RPMB on a storage which doesn't have its own firmware.
>>>>> Primarily, NAND/NOR storage. Unlike UFS/eMMC storage, NAND/NOR storage does not
>>>>> have a storage controller where we can program the RPMB key to be used by the
>>>>> firmware. So we must 'emulate' RPMB by moving the storage driver within QTEE
>>>>> and making the driver hold/use the key.
>>>>>
>>>>> Qualcomm compute SoCs (Glymur, Hamoa) have RPMB available on SPI-*NOR* storage,
>>>>> and a driver for communicating with it is also available in QTEE. And so, these
>>>>> have 'emulated' RPMB.
>>>>
>>>> This needs to be explained in the cover letter.
>>>>
>>>
>>> Ack. 
>>>>>
>>>>> I will add this detail in an updated cover letter.
>>>>>>
>>>>>>> platforms where RPMB is not located within SPI-NOR storage and instead
>>>>>>> located on UFS/EMMC storage, non-volatile EFI variables can only be set via
>>>>>>> a callback request from the UEFI Secure Application to the RPMB service
>>>>>>> running in user-space (within the QTEE supplicant [1]).
>>>>>>
>>>>>> Can it be moved to the kernel?
>>>>>
>>>>> We have a plan to move the RPMB service to the kernel similar to OPTEE:
>>>>> https://elixir.bootlin.com/linux/v7.2-rc3/source/drivers/tee/optee/rpc.c#L449
>>>>>
>>>>> It is a work in progress. Once this happens, we don't need QTEE supplicant available
>>>>> on the Linux distribution.
>>>>
>>>> Ok.
>>>>
>>>>>
>>>>>>
>>>>>>>
>>>>>>> Unlike the QCOM-TEE driver, the QSEECOM driver (used by the current
>>>>>>> QSEECOM based uefisecapp) does not support callback requests.
>>>>>>
>>>>>> How did it work then? I think Windows has been perfectly using QSEECOM
>>>>>> rather than QTEE.
>>>>>
>>>>> It works because Windows on Arm on Qualcomm has SPI-NOR storage. A driver for which
>>>>
>>>> I have WoA devices without SPI NOR. Windows still can store UEFI
>>>> variables.
>>>>
>>>
>>> Ahh, the key point here is 'Windows'. Windows has a separate way of providing
>>> RPMB access via a service in the TrEE driver within the OS:
>>> https://github.com/microsoft/Windows-driver-samples/tree/main/TrEE
>>>
>>> However, the Linux QSEECOM driver we have here in upstream does not have that support.
>>> And so without the QCOMTEE + QTEE supplicant combination, we cannot access EFI
>>> variables on these Qualcomm WoA platforms when they boot with upstream Linux.
>>
>> So, this must be fixed, I assume? What is the ETA?
>>
> 
> I agree, it will have to be a separate effort. If new firmware QTEE releases are not
> being rolled out for these existing WoA devices, and if their RPMB exists on UFS/eMMC
> then the only way to support EFI variable is to:
> 1. Add support for callback requests in the upstream QSEECOM driver.
> 2. Add support for RPMB listener in kernel which routes the RPMB frames from QTEE to
>    the RPMB device via the QSEECOM driver.
> 
> This is significant effort for supporting a protocol which is deprecated on the QTEE
> side moving forward. That being said, I do not discourage this effort. We can think of
> a plan if we really want to support these devices. I will be happy to engage.
> 
>>>
>>>>> is available within QTEE, and so QTEE does not need to make a callback request
>>>>> to Linux to request RPMB frame routing. However, in case of UFS/eMMC storage the
>>>>> driver only exists in the Linux kernel and so QTEE must make a callback request.
>>>>>
>>>>> And so, if you try to use the QSEECOM driver to write EFI-variables to RPMB
>>>>> on a device with UFS/eMMC storage, it won't work.
>>>>
>>>> Yep. It seems to work under Windows though.
>>>>
>>>
>>> As explained above, the mechanism is different for Windows. A different driver
>>> and a different protocol. :)
>>
>> Let me be very explicit here. The path used by Windows is tested and
>> verified to work on a plethora of the devices. Those devices must work
>> with Linux too, so, in my opinion, we should use the same firmware path
> 
> Agreed, as mentioned above, we can think of a plan to support these devices by extending
> the QSEECOM driver.
> 
>> and the same firmware interfaces as used by Windows.
>>
> 
> The interfaces used on Windows by the TrEE driver are different as per the information
> I obtained from Windows team. But we don't need to worry about that, we already have
> QSEECOM in upstream which we can extend.
> 
>>>>>>> And on
>>>>>>> certain Qualcomm platforms such as the RB3Gen2, attempts to access the
>>>>>>> QSEECOM interface fail due to lack of support within Qualcomm TEE.
>>>>>>
>>>>>> So, I assume, on RB3 Gen2 the QSEECOM doesn't report uefisecapp as
>>>>>> supported. Does it?
>>>>>
>>>>> It doesn't, this API returns -2 if I add RB3 Gen2 in the allow-list for QSEECOM:
>>>>> https://elixir.bootlin.com/linux/v7.2-rc3/source/drivers/firmware/qcom/qcom_qseecom.c#L46
>>>>
>>>> Does it support QTEE-based uefi variable storage?
>>>>
>>>
>>> It does, the QTEE-based uefi variable storage app, i.e. uefisecapp is loaded by
>>> UEFI on RB3Gen2, however, the QSEECOM interface on RB3Gen2 is broken so it misreports
>>> it as 'not supported'. But the app is loaded and available, which is why if you apply
>>> this patch series, you can communicate with it. Just make sure you take the QTEE
>>> release mentioned in this cover letter.
>>
>> Can't we fix the QSEECOM instead, if one needs to flash another release
>> anyways?
>>
> 
> QSEECOM is deprecated, requesting support for fixing it is an overhead at this point.
> Even if we take the time to fix it ourselves, it won't help, because the QSEECOM driver
> doesn't support callback requests and a path to the RPMB device within the Linux kernel.
> 
>>>>>>> On these platforms, a TEE based uefisecapp client driver is required to:
>>>>>>> 1. Access cached & volatile EFI variables stored in uefisecapp's memory.
>>>>>>> 2. Ensure persistence of non-volatile EFI variables via writes through
>>>>>>> the RPMB service hosted in the QTEE supplicant.
>>>>>>>
>>>>>>> This series introduces such a uefisecapp TEE client driver for the
>>>>>>> aforementioned Qualcomm platforms which installs efi-var operations _if_
>>>>>>> the QCOMTEE driver registers support for an object-IPC based uefisecapp
>>>>>>> service on the TEE bus during its probe. Only new QTEE firmware versions
>>>>>>> available at [2] provide this support.
>>>>>>
>>>>>> What about existing WoA devices?
>>>>>
>>>>> New Windows on Arm devices like Hamoa/Glymur work perfectly fine with existing
>>>>> QSEECOM based uefisecapp. But they will also work with this new QCOMTEE based
>>>>> uefisecapp once they upgrade their firmware.
>>>>
>>>> Do extisting commercial devices suppot it? For example, does Lenovo T14s
>>>> support it? Will it continue to work with this patchset in place?
>>>
>>> Existing devices like the Lenovo T14s do not have mature QCOMTEE/SMCInvoke support
>>> on QTEE side and new QTEE versions for it are not being rolled out. However, this
>>> QCOMTEE based uefisecapp driver and the QSEECOM based uefisecapp driver can co-exist.
>>> It will not cause any breakage of existing working functionality since the QSEECOM
>>> path can probe and continue as usual.
>>
>> My understanding was that QTEE path completely disables the QSEECOM
>> path, does it not?
>>
> 
> By 'QTEE path', I believe you mean the 'QCOMTEE/SMCInvoke' protocol path.
> 
> No, both SMCInvoke/QCOMTEE and QSEECOM paths can be supported simultaneously within QTEE.
> QTEE does not disable the QSEECOM path when it enables the SMCInvoke/QCOMTEE one.
> 
> You can have both QSEECOM and SMCInvoke clients running together on a Qualcomm platform.
> QTEE doesn't impose any restrictions. The control/data paths within QTEE for these
> two protocols are completely isolated from each other.
> 
>>>
>>> As per your comments on patch 6 of this series, I plan to enable the QCOMTEE based
>>> uefisecapp as default 'm'. That way we don't need to enable one over the other and
>>> will continue supporting all existing functionality while extending it for devices
>>> with UFS/eMMC storage and running upstream Linux.
>>>
>>> Do let me know your opinion on it.
>>
>> My opinion is very obvious by now. Existing devices should work. _Must_
>> work. They provide the reference interface. Make them work first and
>> work good. Then explain, why the other interface is better (I fail to
>> see it from your cover letter or from any of the commit messages).
>>
>> When I take a Glumur laptop from the market shelf, will it be QSEECOM or
>> QCOMTEE? If I take the next-generation-after-Glymur, will QTEE interface
>> for uefisecapp be supported there? Will it be used by Windows?
>>
>> I think the series fails to answer, why do we need another mechanism, if
>> we already have one which has been working for the past N years and
>> which is supposed to work for another M years?
>>
> 
> At this point, we have the following categories of devices:
> 1. Devices with only QSEECOM support, but no support for callbacks/RPMB listener within
> Linux QSEECOM driver.
> Example, MSM8998 and older WoA laptops. These are very old devices (at least more than
> 6-7 years old).
> 
> 2. Devices with both QSEECOM and SMCInvoke/QCOMTEE support.
> Example, SM8650, *Glymur*. These are relatively new devices (2-5 years old).
> 
> 3. Devices with only SMCInvoke/QCOMTEE support.
> Example, RB3Gen2/Kodiak, IQ-9075/LeMans and newer devices which might not have
> QSEECOM support in the future since QTEE team has deprecated QSEECOM.
> 
> This patch series helps devices in category 2 and 3. Without the mechanism introduced
> by this series, we will end up in a situation where EFI variable based use-cases will
> become impossible on at least category 3 of devices. We must conform to the reality
> that QTEE firmware is transitioning to SMCInvoke as the protocol of choice with
> long-term committed support.
> 
> At the same time, I am aligned that we must think of a way to support devices in category 1
> which is what you really care about. The QCOMTEE and QSEECOM drivers can co-exist, and so
> by adding support for both this patch series and callback requests to the QSEECOM driver
> (at a later point of time via a separate series) we will be able to provide EFI variable
> support on all Qualcomm platforms under the sun. This will accomplish our common goal.
> 
> I will add this information in the cover letter in a concise manner.
>  
>>>> What about other existing devices? We have WoA devices starting with
>>>> MSM8998. The QSEECOM driver works on them, but, as you mentioned, it
>>>> can't flash updates to the backing storage.
>>>>
>>>
>>> Unfortunately, unless we roll out new QTEE firmware versions for devices like MSM8998
>>> with QCOMTEE/SMCInvoke support + access to the Uefisecapp over SMCInvoke protocol,
>>> they cannot be helped with this series.
>>
>> So, I'd say, the series is strange. We are proposing something which is
>> not rolled out, which is not supported by the exsiting commercial
>> devices, etc. On the other hand we have future gaps which are known.
>> This doesn't sound correctly.
>>
> 
> We are proposing a mechanism which supports the majority of Qualcomm devices in the market
> launched within the last 5 years and also the upcoming ones. The category of devices which
> are not helped by this series are extremely old (at least 6+ years). Regardless, I am not
> pushing the view that we do not care about those devices, just that the route to helping
> them is different and orthogonal to this series and I am happy to engage on it separately. 
>>>>> I need to double-check but this firmware release for Glymur on Qualcomm Linux
>>>>> is probably carrying the support for QCOMTEE based uefisecapp access:
>>>>> https://github.com/qualcomm-linux/meta-qcom/commit/728251fcbe5113980805ea6c571e33235062ee71
>>>>> If not, the next release will definitely have it since I have merged support for
>>>>> this in QTEE and talked to the boot firmware release team about this.
>>>>
>>>> Does it work on the CRD?
>>>>
>>>
>>> Yes it does, I have validated on Glymur CRD by locally switching it from the current QSEECOM
>>> based uefisecapp to this new QCOMTEE based uefisecapp. This is the QTEE release which
>>
>> Why do we need to switch the app? Why is the old one worth switching?
>>
> 
> You do not need to, Glymur supports both QSEECOM and QCOMTEE/SMCInvoke. I just used Glymur
> as an example to show that both work there and if a user wants he can chose one over the other
> (It really doesn't matter). Glymur sits in the middle of the old and the new, it is a category 2
> device as mentioned above. 
>>> needs to be consumed for it:
>>> https://github.com/qualcomm-linux/meta-qcom/commit/5590c1dc631827624c110df282965b85ef2a2e60 
>>>
>>>>>
>>>>> The next planned firmware upgrade for Hamoa will also provide this support for
>>>>> Qualcomm Linux. And similarly, for all other targets being supported upstream.
>>>>
>>>> So, we are forcing users to upgrade to the new firmware? That doesn't
>>>> sound nice.
>>>>
>>>
>>> We have an open ecosystem for all devices supported by the Qualcomm Linux distribution,
>>> users can easily consume new releases (and new QTEE versions) to access new features.
>>> Until now, developers/users of RB3Gen2 or IQ-9075 could not access EFI variables to
>>
>> What stopped us from delivering the TZ apps compatible with the existing
>> interface?
>>
> 
> QSEECOM support is deprecated on IQ-9075 and broken on RB3Gen2.
> 
>>> develop use-cases such as secure-boot key revocation, but by taking this patch series
>>> as part of a subsequent Qualcomm Linux release, they will be able to.
>>>
>>>>>>> Thus, QCOMTEE now maintains a static list of always-available object-IPC
>>>>>>> based secure services exposed by QTEE. These services are implemented either
>>>>>>> within the QTEE kernel or within a pre-loaded Trusted Application (TA)
>>>>>>> usually loaded by the bootloader. The uefisecapp TA is an example of a
>>>>>>> preloaded TA loaded by UEFI. A static list is required since QTEE does not
>>>>>>> yet expose any way to dynamically query and enumerate the services exposed by
>>>>>>> it.
>>>>>>
>>>>>> Can it be fixed instead of having static lists? In the end, we can't
>>>>>> guarantee that users update the firmware.
>>>>>>
>>>>>
>>>>> Unfortunately, no existing QTEE release out there currently has this support.
>>>>> But support for this is currently being added by QTEE team last I checked with them.
>>>>> Once it is available, and a new QTEE firmware release is out there, we will add
>>>>> support for dynamically querying QTEE services in the QCOMTEE driver. 
>>>>
>>>> It seems you are still rolling out QTEE-based support. In such a case,
>>>> please go back and implement dynamic detection of QTEE services.
>>>> Otherwise it would be a nightmare.
>>>>
>>>
>>> We are working on it, but until then there is no overhead involved in maintaining
>>> this static list of services because we don't have to extend/modify this list when
>>> adding support for a new Qualcomm platform upstream. If a particular service from
>>> the list is not implemented/accessible from QTEE we log the event and silently avoid
>>> probing the TEE driver for the service. We also don't add platform specific services
>>> here. So the list doesn't need to be extended on a per-platform basis.
>>>
>>> So unlike the QSEECOM driver, we don't have to keep maintaining this list forever
>>> for all new platforms.
>>
>> I don't see a difference. You are saying that the list implementation is
>> good, it silintly skips the unavailable services, etc., and then you say
>> that you don't have to keep maintaining the list.
>>
> 
> We only have to add services to this list when a client driver appears for it. For
> example, this TPM series by Kuldeep:
> https://lore.kernel.org/all/20260831-tpm_qcom_driver-v1-1-6f16fa6924fa@xxxxxxxxxxxxxxxx/
> 
> We don't need to maintain this list on a per-platform basis unlike QSEECOM:
> https://elixir.bootlin.com/linux/v7.2-rc7/source/drivers/firmware/qcom/qcom_scm.c#L2289
> 
> Support will arrive for dynamic detection, I have commitment from QTEE team for somewhere
> around end of the year. :)
> 
>>>>>>> To facilitate object-IPC interactions from the kernel-space, this
>>>>>>> series also introduces a tee_client_object_invoke_func() to allow
>>>>>>> invocation of TEE objects similar to the existing tee_client_invoke_func()
>>>>>>> API exported by the TEE subsystem which allows invocation of TEE functions.
>>>>>>> Some suporting changes are also introduced to track and handle operations
>>>>>>> for TEE contexts opened from the kernel-space in the back-end QCOM-TEE
>>>>>>> driver.
>>>>>>>
>>>>>>> Finally and as previously mentioned, access to the object-IPC based uefisecapp
>>>>>>> service is restricted on older QTEE firmware versions. A new QTEE firmware
>>>>>>> release must be picked up from QArtifactory [2] for all upstream supported
>>>>>>> Qualcomm SoCs to enable access to uefisecapp service via the TEE client
>>>>>>> driver.
>>>>>>
>>>>>> What about fused devices?
>>>>>
>>>>> The procedure for updating the firmware on fused devices is slightly different.
>>>>> The firmware images need to be signed by the OEM using the security profile
>>>>> of the chipset before flashing/upgrading them. Security profiles are now public:
>>>>> https://github.com/qualcomm/security-profiles
>>>>
>>>> Will OEMs release new firmware images? What about the devices which are
>>>> already out of the support phase? This whole story rotates about the 'we
>>>> are releasing new firmware with new features' paradigm. However there
>>>> are existing devices in the field, which typically can't be upgraded,
>>>> From your cover letter it seems they can't support UEFI variables
>>>> properly. However they do so in Windows.
>>>>
>>>
>>> Yes Dmitry, this series is effectively forward looking. QSEECOM protocol/driver
>>> support is essentially deprecated on QTEE side, no new features added to QTEE support
>>> it, and it also doesn't work on many devices like the RB3Gen2.
>>
>> To look forward, we need to have a good firm stand on the ground. We
>> have a half-baked implementation, based on reverse engineering. No RPMB
>> support, etc.
>>
> 
> Agreed. I am happy to engage on a separate series for adding callback support to QSEECOM
> driver along with RPMB listener within the kernel.
>  
>>> For existing devices, if they boot with upstream Linux and have RPMB located on
>>> UFS/eMMC this patch series cannot help them. But the focus of this series is not on the
>>> past, it is on currently supported and future hardware. Every new Qualcomm platform
>>> whose support is being up-streamed or is planned to be up-streamed will have access to
>>> EFI variables via this series.
>>>
>>> If someone wants to add support for older Qualcomm devices to access EFI variables
>>> via QSEECOM that patch series will not conflict with this one. Like I said, both
>>> QSEECOM and QCOMTEE based drivers can co-exist.
>>
>> What will happen if I build both and boot the kernel on the existing
>> devices?
>>
> 
> QSEECOM and its client driver probe first and establishes the path to uefisecapp for
> providing EFI variables service. QCOMTEE and its client silently fail probe.
> 
> Regards,
> Harshal
> 
>