Re: [PATCH v2 08/17] xen/riscv: add new p2m types and helper macros for type classification

[Jan Beulich <jbeulich@xxxxxxxx>]

On 30.06.2025 17:13, Oleksii Kurochko wrote:
> 
> On 6/30/25 4:42 PM, Jan Beulich wrote:
>> On 30.06.2025 16:33, Oleksii Kurochko wrote:
>>> On 6/26/25 4:59 PM, Jan Beulich wrote:
>>>> On 10.06.2025 15:05, Oleksii Kurochko wrote:
>>>>> --- a/xen/arch/riscv/include/asm/p2m.h
>>>>> +++ b/xen/arch/riscv/include/asm/p2m.h
>>>>> @@ -61,8 +61,28 @@ struct p2m_domain {
>>>>>    typedef enum {
>>>>>        p2m_invalid = 0,    /* Nothing mapped here */
>>>>>        p2m_ram_rw,         /* Normal read/write domain RAM */
>>>>> +    p2m_ram_ro,         /* Read-only; writes are silently dropped */
>>>> As indicated before - this type should be added when the special handling 
>>>> that
>>>> it requires is also introduced.
>>> Perhaps, I missed that. I will drop this type for now.
>>>
>>>>> +    p2m_mmio_direct_dev,/* Read/write mapping of genuine Device MMIO 
>>>>> area */
>>>> What's the _dev suffix indicating here?
>>> It indicates that it is device memory, probably, it isn't so necessary in 
>>> case of RISC-V as
>>> spec doesn't use such terminology. In RISC-V there is only available IO, 
>>> NC. And we are
>>> |using PTE_PBMT_IO for |p2m_mmio_direct_dev.
>>>
>>> Maybe it would be better just to rename 
>>> s/p2m_mmio_direct_dev/p2m_mmio_direct_io.
>> And what would the _io suffix indicate, beyond what "mmio" already indicates?
> 
> Just that PBMT_IO will be used for device memory and not PBMT_NC.

And will there (later) also be a p2m_mmio_direct_nc type? If so, I can see the 
point
of the suffix.

Jan