Re: [XEN PATCH v8 05/22] xen/arm: ffa: add flags for FFA_PARTITION_INFO_GET

[Jens Wiklander <jens.wiklander@xxxxxxxxxx>]

On Thu, Apr 13, 2023 at 12:28 PM Henry Wang <Henry.Wang@xxxxxxx> wrote:
>
> Hi Jens,
>
> > -----Original Message-----
> > Subject: [XEN PATCH v8 05/22] xen/arm: ffa: add flags for
> > FFA_PARTITION_INFO_GET
> >
> > Defines flags used for the function FFA_PARTITION_INFO_GET.
>
> Nit: Similarly as my comment for patch #4, I would suggest that in
> commit message you can mention the documentation number and
> the chapter of FFA_PARTITION_INFO_GET. Something like:
> "According to DEN0077A version 1.1 REL0, section 13.8, defines
> flags used for the function FFA_PARTITION_INFO_GET"

I'll add that.

>
> >
> > Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
> > ---
> >  xen/arch/arm/tee/ffa.c | 34 ++++++++++++++++++++++++++++++++++
> >  1 file changed, 34 insertions(+)
> >
> > diff --git a/xen/arch/arm/tee/ffa.c b/xen/arch/arm/tee/ffa.c
> > index ba0942e76993..72e7d0575de5 100644
> > --- a/xen/arch/arm/tee/ffa.c
> > +++ b/xen/arch/arm/tee/ffa.c
> > @@ -57,6 +57,40 @@
> >  #define FFA_MY_VERSION
> > MAKE_FFA_VERSION(FFA_MY_VERSION_MAJOR, \
> >                                                   FFA_MY_VERSION_MINOR)
> >
> > +/*
> > + * Flags to determine partition properties in FFA_PARTITION_INFO_GET
> > return
> > + * message:
> > + * BIT(0): Supports receipt of direct requests
> > + * BIT(1): Can send direct requests
> > + * BIT(2): Can send and receive indirect messages
> > + * BIT(3): Supports receipt of notifications
> > + * BIT(4-5): Partition ID is a PE endpoint ID
> > + * BIT(6): Partition must be informed about each VM that is created by
> > + *         the Hypervisor
> > + * BIT(7): Partition must be informed about each VM that is destroyed by
> > + *         the Hypervisor
> > + * BIT(8): Partition runs in the AArch64 execution state else AArch32
> > + *         execution state
> > + */
> > +#define FFA_PART_PROP_DIRECT_REQ_RECV   BIT(0, U)
> > +#define FFA_PART_PROP_DIRECT_REQ_SEND   BIT(1, U)
> > +#define FFA_PART_PROP_INDIRECT_MSGS     BIT(2, U)
> > +#define FFA_PART_PROP_RECV_NOTIF        BIT(3, U)
> > +#define FFA_PART_PROP_IS_MASK           (3U << 4)
>
> I am a bit confused here, here (3U<<4) is "IS_MASK" but...
>
> > +#define FFA_PART_PROP_IS_PE_ID          (0U << 4)
> > +#define FFA_PART_PROP_IS_SEPID_INDEP    (1U << 4)
> > +#define FFA_PART_PROP_IS_SEPID_DEP      (2U << 4)
> > +#define FFA_PART_PROP_IS_AUX_ID         (3U << 4)
>
> ...here the same value is used for "IS_AUX_ID". According to
> the spec that I referred to, bit[5:4] has the following encoding:
> b'11: Partition ID is an auxiliary ID. Hence I guess the above
> "IS_MASK" should be removed?

FFA_PART_PROP_IS_MASK is supposed to be used when extracting the bits
to compare with one of the other  FFA_PART_PROP_IS_* defines. For
example:
if ((props & FFA_PART_PROP_IS_MASK) == FFA_PART_PROP_IS_PE_ID)

using
if ((props & FFA_PART_PROP_IS_AUX_ID) == FFA_PART_PROP_IS_PE_ID)

doesn't seem right.

>
> I confirm the values of other fields are consistent with the spec.

Thanks,
Jens

>
> Kind regards,
> Henry