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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

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:

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


>          {
>              register_t vcpuid = get_user_reg(regs, 1);
>              register_t epoint = get_user_reg(regs, 2);
> @@ -151,7 +143,6 @@ static bool handle_ssc(struct cpu_user_regs *regs)
>          return true;
>      case ARM_SMCCC_FUNC_NUM(PSCI_0_2_FN_CPU_SUSPEND):
>          perfc_incr(vpsci_cpu_suspend);
> -        if ( psci_mode_check(current->domain, fid) )
>          {
>              uint32_t pstate = get_user_reg(regs, 1);
>              register_t epoint = get_user_reg(regs, 2);
> @@ -162,7 +153,6 @@ static bool handle_ssc(struct cpu_user_regs *regs)
>          return true;
>      case ARM_SMCCC_FUNC_NUM(PSCI_0_2_FN_AFFINITY_INFO):
>          perfc_incr(vpsci_cpu_affinity_info);
> -        if ( psci_mode_check(current->domain, fid) )
>          {
>              register_t taff = get_user_reg(regs, 1);
>              uint32_t laff = get_user_reg(regs,2);
> @@ -172,7 +162,6 @@ static bool handle_ssc(struct cpu_user_regs *regs)
>          return true;
>      case ARM_SMCCC_FUNC_NUM(PSCI_0_2_FN_MIGRATE):
>          perfc_incr(vpsci_cpu_migrate);
> -        if ( psci_mode_check(current->domain, fid) )
>          {
>              uint32_t tcpu = get_user_reg(regs, 1);
>              set_user_reg(regs, 0, do_psci_0_2_migrate(tcpu));
> -- 
> 2.7.4
> 

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