Re: [Xen-devel] [PATCH 13/27] xen/arm: traps: Introduce a helper to read the hypersivor fault register

[Andre Przywara]

Hi,

On 14/08/17 15:24, 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 

Reviewed-by: Andre Przywara 

Cheers,
Andre.

> ---
>  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 498d8c594a..819bdbc69e 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -2530,6 +2530,28 @@ 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);
> @@ -2565,11 +2587,7 @@ 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
> @@ -2711,11 +2729,8 @@ 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);
> 

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[Xen-devel] [PATCH 13/27] xen/arm: traps: Introduce a helper to read the hypersivor fault register

[Julien Grall]

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 
---
 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 498d8c594a..819bdbc69e 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -2530,6 +2530,28 @@ 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);
@@ -2565,11 +2587,7 @@ 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
@@ -2711,11 +2729,8 @@ 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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