Re: [XEN PATCH v8 15/22] xen/arm: ffa: add defines for sharing memory

[Jens Wiklander <jens.wiklander@xxxxxxxxxx>]

Hi Henry,

On Thu, Apr 13, 2023 at 1:47 PM Henry Wang <Henry.Wang@xxxxxxx> wrote:
>
> Hi Jens,
>
> > -----Original Message-----
> > Subject: [XEN PATCH v8 15/22] xen/arm: ffa: add defines for sharing memory
> >
> > Adds defines needed for sharing using the function FFA_MEM_SHARE and
> > friends.
>
> Same as my comments in previous patches, I would suggest to also mention
> the references in commit message.

OK, I'll add something.

>
> >
> > Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
> > ---
> >  xen/arch/arm/tee/ffa.c | 60
> > ++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 60 insertions(+)
> >
> > + * FF-A doesn't have any direct requirments on GlobalPlatform or vice
>
> Typo: s/requirements/requirements/

OK

>
> > + * versa, but an implementation can very well use FF-A in order to provide
> > + * a GlobalPlatform interface on top.
> > + *
> > + * Global Platform specification for TEE requires that any TEE
> > + * implementation should allow to share buffers with size of at least
> > + * 512KB, defined in TEEC-1.0C page 24, Table 4-1,
> > + * TEEC_CONFIG_SHAREDMEM_MAX_SIZE.
> > + * Due to align issue mentioned above, we need to increase this
>
> s/align issue/alignment issue/ ?

Yes, I'll make it "the alignment issue".

>
> > + * value with one.
> > + */
> > +#define FFA_MAX_SHM_PAGE_COUNT          (SZ_512K / FFA_PAGE_SIZE + 1)
> > +
> > +/*
> > + * Limits the number of shared buffers that guest can have at once. This
> > + * is to prevent case, when guests tricks XEN into exhausting its own
>
> Typo: s/tricks/trick/

OK

>
> > + * memory by allocating many small buffers. This value has been chosen
> > + * arbitrary.
>
> Typo: s/ arbitrary/arbitrarily/

OK

>
> > + */
> > +#define FFA_MAX_SHM_COUNT               32
> > +
> > +/* FF-A-1.1-REL0 section 10.9.2 Memory region handle, page 167 */
> > +#define FFA_HANDLE_HYP_FLAG             BIT(63, ULL)
> > +#define FFA_HANDLE_INVALID              0xffffffffffffffffULL
> > +
> > +/*
> > + * Memory attributes: Normal memory, Write-Back cacheable, Inner
> > shareable
> > + * Defined in FF-A-1.1-REL0 Table 10.18 at page 175.
> > + */
> > +#define FFA_NORMAL_MEM_REG_ATTR         0x2fU
> > +/*
> > + * Memory access permissions: Read-write
> > + * Defined in FF-A-1.1-REL0 Table 10.15 at page 168.
> > + */
> > +#define FFA_MEM_ACC_RW                  0x2U
> > +
> > +/* FF-A-1.1-REL0 section 10.11.4 Flags usage, page 184-187 */
> > +/* Clear memory before mapping in receiver */
> > +#define FFA_MEMORY_REGION_FLAG_CLEAR            BIT(0, U)
> > +/* Relayer may time slice this operation */
> > +#define FFA_MEMORY_REGION_FLAG_TIME_SLICE       BIT(1, U)
> > +/* Clear memory after receiver relinquishes it */
> > +#define FFA_MEMORY_REGION_FLAG_CLEAR_RELINQUISH BIT(2, U)
> > +/* Share memory transaction */
> > +#define FFA_MEMORY_REGION_TRANSACTION_TYPE_SHARE (1U << 3)
> > +
>
> I confirm the values introduced in this patch are consistent with in-code
> comments on top of them. Thanks for the pointer :)

:-)

>
> With the typos corrected:
> Reviewed-by: Henry Wang <Henry.Wang@xxxxxxx>

Great.

Thanks,
Jens

>
> Kind regards,
> Henry
>
>
> >  /*
> >   * Flags and field values used for the MSG_SEND_DIRECT_REQ/RESP:
> >   * BIT(31): Framework or partition message
> > --
> > 2.34.1
> >
>