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

[Oleksii Kurochko <oleksii.kurochko@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 1805 bytes --]


On 6/30/25 4:45 PM, Jan Beulich wrote:
> On 30.06.2025 16:38, Oleksii Kurochko wrote:
>> On 6/30/25 4:33 PM, 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.
>> I forgot that p2m_mmio_direct_dev is used by common code for dom0less code (handle_passthrough_prop())
> That'll want abstracting out, I think. I don't view it as helpful to clutter
> RISC-V (and later perhaps also PPC) with Arm-specific terminology.

Would it be better then just rename it to p2m_device? Then it won't clear for Arm which type of MMIO p2m's
types is used as Arm has there MMIO types: *_dev, *_nc, *_c.

As an option (which I don't really like) it could be "#define p2m_mmio_direct_dev ARCH_specific_name" in
asm/p2m.h to not touch common code.

~ Oleksii

[-- Attachment #2: Type: text/html, Size: 3003 bytes --]