Re: [PATCH v2 39/39] xen/riscv: introduce IMSIC h/w interrupt file attaching to vcpu

[Jan Beulich <jbeulich@xxxxxxxx>]

On 22.09.2026 10:31, Oleksii Kurochko wrote:
> On 9/21/26 2:32 PM, Jan Beulich wrote:
>> On 27.08.2026 17:21, Oleksii Kurochko wrote:
>>> Introduce imsic_vsfile_attach() to initialize the AIA-related state needed
>>> for a vCPU to have a working guest interrupt file.
>>>
>>> A guest (VS) interrupt file must be mapped to one of a pCPU's
>>> hardware interrupt files (if they exist), so the pCPU a vCPU will actually
>>> run on needs to be known first. arch_vcpu_create() is therefore not a
>>> suitable place to call vcpu_aia_init(), since the pCPU assigned to a
>>> vCPU can still change before it is first scheduled. To avoid
>>> reassigning the VS interrupt file id and remapping it to a different
>>> pCPU's hardware interrupt file, imsic_vsfile_attach() is called from a
>>> later point in the scheduling path (e.g. continue_new_vcpu()).
>>
>> Hmm, why does first-time handling need to be this different from the
>> handling of a vCPU moving across pCPU-s? The sole difference should be
>> "no state to load" vs "load state that was saved on the old pCPU".
> 
> Generally I think it could be the same but not all the steps done in 
> migration functions aren't needed for new vCPU (despite of the fact they 
> aren't harmful). For new vCPU it seems to me it is enough only to attach 
> h/w interrupt file to vCPU.

Sure, yet still imo you want to aim at re-using as much code as possible,
especially when otherwise you introduce multiple very similar but not
exactly identical variants of logic.

Jan