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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Sun, 2 Jul 2017, Julien Grall wrote:
> 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.

Right, care to submit a patch for CODING_STYLE? I noticed there are no
entries on this topic.

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