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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: ST.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: PAXPR10MB4687.EURPRD10.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-Network-Message-Id: 2695f2b4-e429-4e46-3c49-08d942b06234 X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Jul 2021 08:05:57.8136 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 75e027c9-20d5-47d5-b82f-77d7cd041e8f X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: AtBMpjd7OXkMJCUdwBQTrFl/GXaoy5pdeHWrNvmLwDDAFWc3DALxwZZeHyqIh6vhpddZXuutRC7IixlzHxnqiA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PA4PR10MB4432 X-Proofpoint-ORIG-GUID: f0gF-y0XNNStRcuuwNtT7YJLwNikZY19 X-Proofpoint-GUID: f0gF-y0XNNStRcuuwNtT7YJLwNikZY19 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-07-09_04:2021-07-09,2021-07-09 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 mlxscore=0 suspectscore=0 bulkscore=0 impostorscore=0 malwarescore=0 phishscore=0 spamscore=0 mlxlogscore=999 clxscore=1011 lowpriorityscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2107090040 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Sudeep and all, On Wed, 7 Jul 2021 at 19:52, Sudeep Holla wrote: > > Hi Sumit, > > I was holding off you reply as I didn't have all the background on this. > Achin did mention that this is preparatory work for FFA notifications. > I did mention to him that this is more than that, it is custom extension > to address what FF-A notification is trying to in standard way. > > I share same opinion as Marc Z. > > On Wed, Jul 07, 2021 at 11:22:23AM +0530, Sumit Garg wrote: > > On Tue, 6 Jul 2021 at 18:16, Marc Zyngier wrote: > > [...] > > > > > > > I don't care about OP-TEE. If you are proposing a contract between S > > > and NS, it has to be TEE and OS independent. That's how the > > > architecture works. > > > > > > > Agree, here we are not proposing a common contract among the S and NS > > world that every TEE (based on Arm TrustZone) will use to communicate > > with REE (Linux in our case) but rather an OP-TEE specific > > notifications feature that is built on top of OP-TEE specific ABIs. > > > > And I can see your arguments coming from an FFA perspective but there > > are platforms like the ones based on Armv7 which don't support FFA > > ABI. Maybe Jens can elaborate how this feature will fit in when FFA > > comes into picture? > > > > I can understand that but won't those platforms add the support both in > the kernel(current series) and secure world to address notifications. > While you could argue that it is small extension to what is already prese= nt > but I prefer they support FF-A is they need such a support instead of add= ing > custom mechanisms. It is hard to maintain and each vendor will deviate > from this custom mechanism and soon we will have bunch of them to handle. There exist armv7-a platforms that expect OP-TEE notification support and w= ill not move the FF-A, like the stm32mp15. This platform won't move to FF-A= mainly due to the memory cost of the added SPM layer and the device physic= al constraints. We have a usecase for OP-TEE notification. We're working on the integration= of an SCMI server in OP-TEE. SCMI notification is a feature needed is this= scope and it requires OP-TEE async notification means as those proposed he= re. This OP-TEE async notif also brings a lot of value in OP-TEE as it allows a= OP-TEE secure thread (i.e. executing a trusted application service) to gen= tly wait on a secure interrupt (as a slow bus transaction completion or man= y other usecase) with the CPU relaxed. This support is provided by the prop= osed series. I believe existing device should be able to leverage this OP-T= EE feature without needing their OP-TEE to move to the new FF-A interface. Regards, Etienne > > [...] ST Restricted