Re: [Xen-devel] [PATCH v2 4/4] vsmc: psci: remove 64 bit mode check

[Julien Grall <julien.grall@xxxxxxx>]

Hi,

On 06/30/2017 10:19 PM, Stefano Stabellini wrote:
> On Thu, 22 Jun 2017, Volodymyr Babchuk wrote:
> > PSCI handling code had helper routine that checked calling convention.
> > It does not needed anymore, because:
> >
> >   - Generic handler checks that 64 bit calls can be made only by
> >     64 bit guests.
> >
> >   - SMCCC requires that 64-bit handler should support both 32 and 64 bit
> >     calls even if they originate from 64 bit caller.
> >
> > This patch removes that extra check.
> >
> > Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
> > ---
> >   xen/arch/arm/vsmc.c | 13 +------------
> >   1 file changed, 1 insertion(+), 12 deletions(-)
> >
> > diff --git a/xen/arch/arm/vsmc.c b/xen/arch/arm/vsmc.c
> > index 5f10fd1..1983e0e 100644
> > --- a/xen/arch/arm/vsmc.c
> > +++ b/xen/arch/arm/vsmc.c
> > @@ -98,12 +98,6 @@ static bool handle_arch(struct cpu_user_regs *regs)
> >       return false;
> >   }
> >   
> > -/* helper function for checking arm mode 32/64 bit */
> > -static inline int psci_mode_check(struct domain *d, register_t fid)
> > -{
> > -        return !( is_64bit_domain(d)^( (fid & PSCI_0_2_64BIT) >> 30 ) );
> > -}
> > -
> >   /* PSCI 2.0 interface */
> >   static bool handle_ssc(struct cpu_user_regs *regs)
> >   {
> > @@ -125,8 +119,7 @@ static bool handle_ssc(struct cpu_user_regs *regs)
> >           return true;
> >       case ARM_SMCCC_FUNC_NUM(PSCI_0_2_FN_MIGRATE_INFO_UP_CPU):
> >           perfc_incr(vpsci_migrate_info_up_cpu);
> > -        if ( psci_mode_check(current->domain, fid) )
> > -            set_user_reg(regs, 0, do_psci_0_2_migrate_info_up_cpu());
> > +        set_user_reg(regs, 0, do_psci_0_2_migrate_info_up_cpu());
> >           return true;
> >       case ARM_SMCCC_FUNC_NUM(PSCI_0_2_FN_SYSTEM_OFF):
> >           perfc_incr(vpsci_system_off);
> > @@ -140,7 +133,6 @@ static bool handle_ssc(struct cpu_user_regs *regs)
> >           return true;
> >       case ARM_SMCCC_FUNC_NUM(PSCI_0_2_FN_CPU_ON):
> >           perfc_incr(vpsci_cpu_on);
> > -        if ( psci_mode_check(current->domain, fid) )
> I would prefer if the `return true' was within the { } block. But anyway
> it's just a code style issue, so:
Well, I think we should keep the coding style consistent within 
arch/arm. If we have the return true within {} in other place. Then this 
should be done here.
In general, { } should only be used to en-globe everything in a case or 
for if/else/while/for with more than a line. All the other kind of { } 
should be avoided. I particularly dislike any code doing
code

{
   variable definition;

   code
}

code

Unless you have a strong reason to do it (avoiding reworking the code is 
not one), I will nack any code resulting to that.
Cheers,

--
Julien Grall

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