Re: [Xen-devel] [PATCH v2 3/3] xen/arm: vpsci: Move PSCI function dispatching from vsmc.c to vpsci.c

[Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>]

On 06.02.18 17:39, Julien Grall wrote:
> On 02/06/2018 03:28 PM, Volodymyr Babchuk wrote:
> > Hi Julien,
> >
> > On 06.02.18 16:45, Julien Grall wrote:
> >
> > [...]
> > > > > > > +/*
> > > > > > > + * PSCI 0.2 or later calls. It will return false if the function 
> > > > > > > ID is
> > > > > > > + * not handled.
> > > > > > > + */
> > > > > > > +bool do_vpsci_0_2_call(struct cpu_user_regs *regs, uint32_t fid)
> > > > > > > +{
> > > > > > > +    /*
> > > > > > > +     * /!\ VPSCI_NR_FUNCS (in asm-arm/vpsci.h) should be updated 
> > > > > > > when
> > > > > > > +     * adding/removing a function
> > > > > > > +     */
> > > > > > Should we also update revision of SSSC interface as well? SMCCC 
> > > > > > requires this.
> > > > > Meh, you can't rely on the SSSC revision most of the time as the 
> > > > > version for PSCI is done through PSCI_get_version. I can add a 
> > > > > comment if you want.
> > > > Yes, I agree with you. But section 5.4 of SMCCC 1.0 applies to SSSC 
> > > > as well. So you can write something like "ARM SMCCC requires that 
> > > > SSSC revision and function call count should be updated every time 
> > > > you add or remove a function"
> > > Usually we update versioning number only once per release. I would 
> > > follow the same approach for this one. So I would suggest
> > It is not stated clearly in SMCCC, but I've got a felling that 
> > revision belongs not to product version, but to SMC interface version. 
> > So I see no reason to change revision, if there was no changes to 
> > interface itself.
> > I'm okay witch changing revision only one time per release, but only
> > if there was changes to PSCI interface. On other hand, person
> > responsible for release need to track if there was any changes in PSCI
> > and act accordingly. This is not very convenient.
> > So, I would prefer to change revision in the same patch (or patch 
> > series) which alters the interface.
> At the end of the day this is closely tie to product revision. A new 
> revision may produce change in the implementation and therefore the 
> version will be bumped. But there are always exception when you do a 
> release just for bug fix.
> This is the same for Xen, we only change interface version if something 
> major as changed. If nothing, then the version stays the same.
Then I'm okay with this. I just wanted to sure that we are on the same page.

> > > "VPSCI_NR_FUNCS (in asm-arm/vpsci.h) should be updated when adding 
> > > removing a function. SSCCC_SMCCC_*_REVISION should be updated once 
> > > per Xen release".
> > And who will be responsible for this?
> The first patch modifying the SMCCC implementation after the tree is 
> re-opened. This is how we deal the rest of the versions in Xen, and it 
> works.
I'm good with this then.


--
Volodymyr Babchuk

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