Re: [Xen-devel] [PATCH v2 10/24] xen/arm: traps: Introduce a helper to read the hypersivor fault register

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 12 Sep 2017, Julien Grall wrote:
> While ARM32 has 2 distinct registers for the hypervisor fault register
> (one for prefetch abort, the other for data abort), AArch64 has only
> one.
> 
> Currently, the logic is open-code but a follow-up patch will require to
> read it too. So move the logic in a separate helper and use it instead
> of open-coding it.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>     Changes in v2:
>         - Add Andre's reviewed-by
> ---
>  xen/arch/arm/traps.c | 35 +++++++++++++++++++++++++----------
>  1 file changed, 25 insertions(+), 10 deletions(-)
> 
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index 967bfea4ed..2e48089d61 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -2549,6 +2549,28 @@ done:
>      if (first) unmap_domain_page(first);
>  }
>  
> +/*
> + * Return the value of the hypervisor fault address register.
> + *
> + * On ARM32, the register will be different depending whether the
> + * fault is a prefetch abort or data abort.
> + */
> +static inline vaddr_t get_hfar(bool is_data)
> +{
> +    vaddr_t gva;
> +
> +#ifdef CONFIG_ARM_32
> +    if ( is_data )
> +        gva = READ_CP32(HDFAR);
> +    else
> +        gva = READ_CP32(HIFAR);
> +#else
> +    gva =  READ_SYSREG(FAR_EL2);
> +#endif
> +
> +    return gva;
> +}
> +
>  static inline paddr_t get_faulting_ipa(vaddr_t gva)
>  {
>      register_t hpfar = READ_SYSREG(HPFAR_EL2);
> @@ -2584,11 +2606,7 @@ static void do_trap_instr_abort_guest(struct 
> cpu_user_regs *regs,
>      paddr_t gpa;
>      mfn_t mfn;
>  
> -#ifdef CONFIG_ARM_32
> -    gva = READ_CP32(HIFAR);
> -#else
> -    gva = READ_SYSREG64(FAR_EL2);
> -#endif
> +    gva = get_hfar(false /* is_data */);
>  
>      /*
>       * If this bit has been set, it means that this instruction abort is 
> caused
> @@ -2730,11 +2748,8 @@ static void do_trap_data_abort_guest(struct 
> cpu_user_regs *regs,
>          return __do_trap_serror(regs, true);
>  
>      info.dabt = dabt;
> -#ifdef CONFIG_ARM_32
> -    info.gva = READ_CP32(HDFAR);
> -#else
> -    info.gva = READ_SYSREG64(FAR_EL2);
> -#endif
> +
> +    info.gva = get_hfar(true /* is_data */);
>  
>      if ( hpfar_is_valid(dabt.s1ptw, fsc) )
>          info.gpa = get_faulting_ipa(info.gva);
> -- 
> 2.11.0
> 

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