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From: Julien Grall <julien.grall@arm.com>
To: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Cc: "tee-dev@lists.linaro.org" <tee-dev@lists.linaro.org>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	Ian Jackson <ian.jackson@eu.citrix.com>, Wei Liu <wl@xen.org>
Subject: Re: [Xen-devel] [PATCH v6 09/10] tools/arm: tee: add "tee" option for xl.cfg
Date: Wed, 19 Jun 2019 11:30:27 +0100
Message-ID: <e9b05f95-b6a1-a4f6-87cb-147b235f30e8@arm.com> (raw)
In-Reply-To: <87sgs67w94.fsf@epam.com>

Hi,

On 18/06/2019 16:23, Volodymyr Babchuk wrote:
> 
> Julien Grall writes:
> 
>> On 6/18/19 3:30 PM, Volodymyr Babchuk wrote:
>>>
>>>
>>> Julien Grall writes:
>>>
>>>> On 18/06/2019 12:19, Volodymyr Babchuk wrote:
>>>>>
>>>>> Hi Julien,
>>>>
>>>> Hi,
>>>>
>>>>>
>>>>> Julien Grall writes:
>>>>>>> +
>>>>>>> +=item B<optee>
>>>>>>> +
>>>>>>> +Allow a guest to use OP-TEE. Note that a virtualization-aware OP-TEE
>>>>>>> +is required for this. If this option is selected, guest will be able
>>>>>>
>>>>>> OOI, what happen if OP-TEE does not support virtualization. Will Xen
>>>>>> forbid to use it?
>>>>> Yes, Xen will get an error from OP-TEE during domain construction. This
>>>>> will lead to domain creation failure.
>>>>
>>>> This is a bit odd. It means we have no way to know in advance whether
>>>> OP-TEE will be able to create a client.
>>> Yes. There can be at least two reasons for this:
>>> 1. OP-TEE is built without virtualization support at all
>>> 2. OP-TEE have no resources for a new guest
>>>
>>>> In other word, when the
>>>> mediator is built in Xen, all existing setup with OP-TEE (and
>>>> no-virtualization) will fail.
>>> Right. If user provides DTB with 'optee' node, but OP-TEE is build without
>>> virtualization support, Dom0 will not be created. This can be fixed by
>>> adding new capability flag into OP-TEE, that tells Xen about
>>> virtualization support. For some reason I missed this when I implemented
>>> VM support in OP-TEE :(
>>>
>>>> My expectation is Xen should be able to know whether the mediator can be used.
>>> I need to implement additional capability flag in the OP-TEE. This is
>>> not so hard, but it will be available only in the next release. For now,
>>> we can document this limitation somewhere.
>>
>> Is OP-TEE already released with virtualization? If not, when will it be?
> Yes, OP-TEE 3.5.0 was released on 26 April 2019 and it includes
> virtualization support.

Ok. Please try to solve this problem for the next release.

For now, I think there are a way to workaround the lack of a feature flag. In 
the detection of OP-TEE, you can try to create a client. If it fails, then it 
means OP-TEE does not support virtualization.

This is assuming that OP-TEE will fail gracefully.

Cheers,

-- 
Julien Grall

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  reply index

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-11 18:46 [Xen-devel] [PATCH v6 00/10] TEE mediator (and OP-TEE) support in XEN Volodymyr Babchuk
2019-06-11 18:46 ` [Xen-devel] [PATCH v6 01/10] xen/arm: add generic TEE mediator framework Volodymyr Babchuk
2019-06-17 16:11   ` Stefano Stabellini
2019-06-11 18:46 ` [Xen-devel] [PATCH v6 02/10] xen/arm: optee: add OP-TEE header files Volodymyr Babchuk
2019-06-15 18:39   ` Julien Grall
2019-06-17 15:24     ` Julien Grall
2019-06-17 16:28       ` Stefano Stabellini
2019-06-17 16:34         ` Julien Grall
2019-06-17 17:28           ` Stefano Stabellini
2019-06-19  8:20             ` Lars Kurth
2019-06-19 10:26               ` Julien Grall
2019-06-11 18:46 ` [Xen-devel] [PATCH v6 03/10] xen/arm: optee: add OP-TEE mediator skeleton Volodymyr Babchuk
2019-06-19 11:01   ` Julien Grall
2019-06-19 11:03     ` Julien Grall
2019-06-19 15:44       ` Volodymyr Babchuk
2019-06-11 18:46 ` [Xen-devel] [PATCH v6 04/10] xen/arm: optee: add fast calls handling Volodymyr Babchuk
2019-06-11 18:46 ` [Xen-devel] [PATCH v6 05/10] xen/arm: optee: add std call handling Volodymyr Babchuk
2019-06-11 18:46 ` [Xen-devel] [PATCH v6 06/10] xen/arm: optee: add support for RPC SHM buffers Volodymyr Babchuk
2019-06-11 18:46 ` [Xen-devel] [PATCH v6 07/10] xen/arm: optee: add support for arbitrary shared memory Volodymyr Babchuk
2019-06-11 18:46 ` [Xen-devel] [PATCH v6 08/10] xen/arm: optee: add support for RPC commands Volodymyr Babchuk
2019-06-11 18:46 ` [Xen-devel] [PATCH v6 09/10] tools/arm: tee: add "tee" option for xl.cfg Volodymyr Babchuk
2019-06-15 19:10   ` Julien Grall
2019-06-18 11:19     ` Volodymyr Babchuk
2019-06-18 12:49       ` Julien Grall
2019-06-18 14:30         ` Volodymyr Babchuk
2019-06-18 15:19           ` Julien Grall
2019-06-18 15:23             ` Volodymyr Babchuk
2019-06-19 10:30               ` Julien Grall [this message]
2019-06-11 18:46 ` [Xen-devel] [PATCH v6 10/10] tools/arm: optee: create optee firmware node in DT if tee=optee Volodymyr Babchuk
2019-06-19 11:08 ` [Xen-devel] [PATCH v6 00/10] TEE mediator (and OP-TEE) support in XEN Julien Grall

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