Re: [PATCH v15 16/21] KVM: arm64: Handle guest_memfd-backed guest page faults

[Kunwu Chan <kunwu.chan@linux.dev>]

On 2025/7/23 16:20, Marc Zyngier wrote:
> On Tue, 22 Jul 2025 13:31:34 +0100,
> Kunwu Chan <kunwu.chan@linux.dev> wrote:
>> On 2025/7/18 00:27, Fuad Tabba wrote:
>>> Add arm64 architecture support for handling guest page faults on memory
>>> slots backed by guest_memfd.
>>>
>>> This change introduces a new function, gmem_abort(), which encapsulates
>>> the fault handling logic specific to guest_memfd-backed memory. The
>>> kvm_handle_guest_abort() entry point is updated to dispatch to
>>> gmem_abort() when a fault occurs on a guest_memfd-backed memory slot (as
>>> determined by kvm_slot_has_gmem()).
>>>
>>> Until guest_memfd gains support for huge pages, the fault granule for
>>> these memory regions is restricted to PAGE_SIZE.
>> Since huge pages are not currently supported, would it be more
>> friendly to define  sth like
>>
>> "#define GMEM_PAGE_GRANULE PAGE_SIZE" at the top (rather than
>> hardcoding PAGE_SIZE)
>>
>>   and make it easier to switch to huge page support later?
> No. PAGE_SIZE always has to be the fallback, no matter what. When (and
> if) larger mappings get supported, there will be extra code for that
> purpose, not just flipping a definition.
>
> Thanks,
>
> 	M.

Got it, no questions here. Feel free to add my "Reviewed-by" tag to the 
patch.

Reviewed-by: Tao Chan <chentao@kylinos.cn>

Thanks,
	TAO.
---
“Life finds a way.”