RE: [PATCH v2 3/3] scsi: ufs: core: Add OP-TEE based RPMB driver for UFS devices

[Avri Altman]

> 
> On Wed, 2025-10-01 at 10:06 +0000, Avri Altman wrote:
> > > From: Bean Huo <beanhuo@xxxxxxxxxx>
> > >
> > > This patch adds OP-TEE based RPMB support for UFS devices. This
> > > enables secure RPMB operations on UFS devices through OP-TEE,
> > > providing the same functionality available for eMMC devices and
> > > extending kernel-based secure storage support to UFS-based systems.
> > >
> > > Benefits of OP-TEE based RPMB implementation:
> > > - Eliminates dependency on userspace supplicant for RPMB access
> > > - Enables early boot secure storage access (e.g., fTPM, secure UEFI
> > > variables)
> > > - Provides kernel-level RPMB access as soon as UFS driver is
> > > initialized
> > > - Removes complex initramfs dependencies and boot ordering
> > > requirements
> > > - Ensures reliable and deterministic secure storage operations
> > > - Supports both built-in and modular fTPM configurations
> > >
> > > Co-developed-by: Can Guo <can.guo@xxxxxxxxxxxxxxxx>
> > > Signed-off-by: Can Guo <can.guo@xxxxxxxxxxxxxxxx>
> > > Signed-off-by: Bean Huo <beanhuo@xxxxxxxxxx>
> > Reviewed-by: Avri Altman <avri.altman@xxxxxxxxxxx>
> >
> > Nit: Would it make sense to simplify things, e.g. :
> > Instead of struct list_head rpmbs;
> > Use:
> > struct ufs_rpmb_dev *rpmbs[4];
> 
> 
> Hi Avri,
> 
> I am working on the next version, seems we should keep struct list_head
> rpmbs.
> 
> On the hot path, runtime RPMB I/O operations use dev_get_drvdata(dev) to
> get the device pointer directly, never searching through hba->rpmbs. Array's
> O(1) direct access advantage is therefore irrelevant. and the list is only
> accessed during probe/remove (one-time operations at boot/shutdown)
> where performance differences are negligible. The list iterates only over active
> regions without NULL checks, while an array requires checking all 4 slots.
> 
> List uses 16 bytes per active region, array uses 32 bytes (4 × 8-byte pointers)
> regardless of how many regions are active, most of UFS devices only enabled
> 1-2 RPMB regions, making the list more memory-efficient, right?
Yes.  The code looks good as it is.

Thanks,
Avri

> 
> 
> how do you think?
> 
> Kind regards,
> Bean
> 
>