Re: [Xen-devel] [PATCH 1/7] xen/arm: vpsci: Remove parameter 'ver' from do_common_cpu

[Volodymyr Babchuk <vlad.babchuk@xxxxxxxxx>]

Hi Julien,

On 5 February 2018 at 15:20, Julien Grall <julien.grall@xxxxxxx> wrote:
> Currently, the behavior of do_common_cpu will slightly change depending
> on the PSCI version passed in parameter. Looking at the code, more the
> specific 0.2 behavior could move out of the function or adapted for 0.1:
>
>     - x0/r0 can be updated on PSCI 0.1 because general purpose registers
>     are undefined upon CPU on.
>     - PSCI 0.1 does not defined PSCI_ALREADY_ON. However, it would be
>     safer to bail out if the CPU is already on.
>
> Based on this, the parameter 'ver' is removed and do_psci_cpu_on
> (implementation for PSCI 0.1) is adapted to avoid returning
> PSCI_ALREADY_ON.
>
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
Reviewed-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>

> ---
>  xen/arch/arm/vpsci.c | 28 ++++++++++++++++++----------
>  1 file changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/xen/arch/arm/vpsci.c b/xen/arch/arm/vpsci.c
> index 884f0fa710..359db884f9 100644
> --- a/xen/arch/arm/vpsci.c
> +++ b/xen/arch/arm/vpsci.c
> @@ -22,7 +22,7 @@
>  #include <public/sched.h>
>
>  static int do_common_cpu_on(register_t target_cpu, register_t entry_point,
> -                       register_t context_id,int ver)
> +                            register_t context_id)
>  {
>      struct vcpu *v;
>      struct domain *d = current->domain;
> @@ -40,8 +40,7 @@ static int do_common_cpu_on(register_t target_cpu, 
> register_t entry_point,
>      if ( is_64bit_domain(d) && is_thumb )
>          return PSCI_INVALID_PARAMETERS;
>
> -    if ( (ver == PSCI_VERSION(0, 2)) &&
> -            !test_bit(_VPF_down, &v->pause_flags) )
> +    if ( !test_bit(_VPF_down, &v->pause_flags) )
>          return PSCI_ALREADY_ON;
>
>      if ( (ctxt = alloc_vcpu_guest_context()) == NULL )
> @@ -55,18 +54,21 @@ static int do_common_cpu_on(register_t target_cpu, 
> register_t entry_point,
>      ctxt->ttbr0 = 0;
>      ctxt->ttbr1 = 0;
>      ctxt->ttbcr = 0; /* Defined Reset Value */
> +
> +    /*
> +     * x0/r0_usr are always updated because for PSCI 0.1 the general
> +     * purpose registers are undefined upon CPU_on.
> +     */
>      if ( is_32bit_domain(d) )
>      {
>          ctxt->user_regs.cpsr = PSR_GUEST32_INIT;
> -        if ( ver == PSCI_VERSION(0, 2) )
> -            ctxt->user_regs.r0_usr = context_id;
> +        ctxt->user_regs.r0_usr = context_id;
>      }
>  #ifdef CONFIG_ARM_64
>      else
>      {
>          ctxt->user_regs.cpsr = PSR_GUEST64_INIT;
> -        if ( ver == PSCI_VERSION(0, 2) )
> -            ctxt->user_regs.x0 = context_id;
> +        ctxt->user_regs.x0 = context_id;
>      }
>  #endif
>
> @@ -93,7 +95,14 @@ static int do_common_cpu_on(register_t target_cpu, 
> register_t entry_point,
>
>  static int32_t do_psci_cpu_on(uint32_t vcpuid, register_t entry_point)
>  {
> -    return do_common_cpu_on(vcpuid, entry_point, 0 , PSCI_VERSION(0, 1));
> +    int32_t ret;
> +
> +    ret = do_common_cpu_on(vcpuid, entry_point, 0);
> +    /*
> +     * PSCI 0.1 does not define the return code PSCI_ALREADY_ON.
> +     * Instead, return PSCI_INVALID_PARAMETERS.
> +     */
> +    return (ret == PSCI_ALREADY_ON) ? PSCI_INVALID_PARAMETERS : ret;
>  }
>
>  static int32_t do_psci_cpu_off(uint32_t power_state)
> @@ -133,8 +142,7 @@ static int32_t do_psci_0_2_cpu_on(register_t target_cpu,
>                                    register_t entry_point,
>                                    register_t context_id)
>  {
> -    return do_common_cpu_on(target_cpu, entry_point, context_id,
> -                            PSCI_VERSION(0, 2));
> +    return do_common_cpu_on(target_cpu, entry_point, context_id);
>  }
>
>  static const unsigned long target_affinity_mask[] = {
> --
> 2.11.0
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxxx
> https://lists.xenproject.org/mailman/listinfo/xen-devel



-- 
WBR Volodymyr Babchuk aka lorc [+380976646013]
mailto: vlad.babchuk@xxxxxxxxx

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