Re: [PATCH v5 2/3] arm/mpu: Introduce `v8r_el1_msa` device tree property for domains

[Luca Fancellu <Luca.Fancellu@xxxxxxx>]

Hi Michal,

>> diff --git a/xen/arch/arm/include/asm/domain_build.h 
>> b/xen/arch/arm/include/asm/domain_build.h
>> index 6674dac5e2f8..50ddc0511e7e 100644
>> --- a/xen/arch/arm/include/asm/domain_build.h
>> +++ b/xen/arch/arm/include/asm/domain_build.h
>> @@ -19,6 +19,27 @@ int prepare_acpi(struct domain *d, struct kernel_info 
>> *kinfo);
>> 
>> int add_ext_regions(unsigned long s_gfn, unsigned long e_gfn, void *data);
>> 
>> +#ifdef CONFIG_MPU
>> +/* Utility function to determine if an Armv8-R processor supports VMSA. */
>> +bool has_v8r_vmsa_support(void);
>> +bool v8r_el1_msa_domain_sanitise_config(
>> +    const struct xen_domctl_createdomain *config);
>> +#else
>> +static inline bool has_v8r_vmsa_support(void)
>> +{
>> +    return false;
>> +}
>> +
>> +static inline bool v8r_el1_msa_domain_sanitise_config(
>> +    const struct xen_domctl_createdomain *config)
> Why can't this function be common? I can see 3 definitions (Arm64 MPU, Arm32
> MPU, MMU) but they do not have anything that would prevent from generalizing
> them in a single function.

I can do a common one I think, just to be aligned, should the common one 
behaves as the current implementation?

Arm64/32 MMU: Only v8r_el1_msa == XEN_DOMCTL_CONFIG_ARM_V8R_EL1_MSA_NONE allowed
Arm64: Only v8r_el1_msa == XEN_DOMCTL_CONFIG_ARM_V8R_EL1_MSA_{NONE,PMSA,VMSA}  
allowed
Arm32: Only v8r_el1_msa == XEN_DOMCTL_CONFIG_ARM_V8R_EL1_MSA_{NONE,PMSA}  
allowed


I’ll fix all your other findings and I’ll address Jan comment on the explicit 
padding + check.

Cheers,
Luca