Re: [PATCH v1 15/27] xen/riscv: add very early virtual APLIC (vAPLIC) initialization support

[Jan Beulich <jbeulich@suse.com>]

On 20.04.2026 12:25, Oleksii Kurochko wrote:
> On 4/16/26 2:42 PM, Jan Beulich wrote:
>> On 14.04.2026 12:27, Oleksii Kurochko wrote:
>>> On 4/2/26 1:58 PM, Jan Beulich wrote:
>>>> On 10.03.2026 18:08, Oleksii Kurochko wrote:
>>>>> @@ -47,6 +48,19 @@ struct intc_hw_operations {
>>>>>                                const struct dt_device_node *intc);
>>>>>    };
>>>>> +
>>>>> +struct vintc {
>>>>> +    const struct intc_info *info;
>>>>
>>>> Isn't this referencing a physical INTC's structure? Why would the virtual
>>>> one's properties have to match that of the physical one?
>>>
>>> It is because of how vAPLIC emulation load and store is working.
>>
>> Thank you very much. This fully explains things, the more that of course
>> emulation of loads and stores comes earlier in this series. Oleksii,
>> really, please.
> 
> Sorry for that. Let me add some extra details where I think that pointer 
> to physical APLIC regs are needed.
> 
> When APLIC tries to access TARGET register it is necessary to update 
> real APLIC as inside this register it is coded information about Hart 
> index, Guest Index (guest interrupt file id) and EIID (External 
> Interrupt Identity). So to do that vintc should have access to physical 
> APLIC registers.
> 
> The similar things I expected to be with some of other register, for 
> example, that one which are stands for turning on/of interrupts (SETIE, 
> CLRIE). If vAPLIC is requesting an enablement of an interrupt then I 
> expect that correspondent physical APLIC register should be updated too 
> as otherwise how then device interrupt will start to occur. So again it
> is needed a pointer to physical APLIC to access these registers.
> 
> Does it make sense at least a little bit now?

Yes. Just that there's a "but": I can't spot any use of the field in this
patch. Hence I still can't say whether I actually agree. Introduce the
field when it's actually needed?

Jan