Re: [PATCH] scsi: ufs: core: Fix RPMB region size detection for UFS 2.2

[Alexey Charkov <alchark@flipper.net>]

On Fri, Jan 30, 2026 at 2:26 PM Bean Huo <huobean@gmail.com> wrote:
>
> On Thu, 2026-01-29 at 21:10 +0400, Alexey Charkov wrote:
> > On Thu, Jan 29, 2026 at 8:53 PM Bean Huo <huobean@gmail.com> wrote:
> > >
> > > On Thu, 2026-01-29 at 11:38 +0400, Alexey Charkov wrote:
> > > > +                       hba->dev_info.rpmb_region_size[0] =
> > > > +                               get_unaligned_be64(desc_buf
> > > > +                                       +
> > > > RPMB_UNIT_DESC_PARAM_LOGICAL_BLK_COUNT)
> > > > +                               <<
> > > > desc_buf[RPMB_UNIT_DESC_PARAM_LOGICAL_BLK_SIZE]
> > > > +                               >> 17; /* convert to 128 kBytes units */
> > > > +               }
> > > >          }
> > >
> > > Hi Alexey,
> > >
> > > thanks for your fix, I didn't notice there is UFS 2.x on the market which
> > > will
> > > use UFS OP-TEE RPMB framework.
> >
> > Hi Bean, it turns out many of the UFS modules for Rockchip RK3576
> > based devices are 2.2. I'm poking around the OP-TEE support on that
> > platform, and discovered that the existing driver didn't see the RPMB
> > at all, spent quite a bit of time trying to figure it out before
> > spotting the difference between the two spec versions :)
> >
> > > here is potential u8 Overflow, since for the UFS3.x+, it is u8 in unit
> > > descriptor, but
> > >
> > >
> > > The calculation can overflow for larger RPMB regions (>32MB):
> > >    - A u8 can only represent up to 255 × 128KB = ~32MB
> > >    - The shift result is assigned directly without bounds checking
> >
> > The spec says it can only be up to 16MB maximum (see section 12.4.3.1
> > RPMB Resources), so it should always fit. Happy to add a comment about
> > that.
> >
> > Best regards,
> > Alexey
>
> Hi Alexey,
>
> Thanks for the clarification on the 16MB RPMB limit - that addresses the
> overflow concern.
>
>
> In your above operation, why not use SZ_128K to avoid the magic number?
> BTW, please update your comment.

Good point, thanks Bean! Will amend in v2.

Best regards,
Alexey