Re: [PATCH v6 1/5] KVM: Implement dirty quota-based throttling of vcpus

[Shivam Kumar <shivam.kumar1@nutanix.com>]

On 07/10/22 11:48 pm, Sean Christopherson wrote:
> On Thu, Sep 15, 2022, Christian Borntraeger wrote:
>> Am 15.09.22 um 15:21 schrieb Christian Borntraeger:
>>> I am wondering if this will work on s390. On s390  we only call
>>> mark_page_dirty_in_slot for the kvm_read/write functions but not
>>> for those done by the guest on fault. We do account those lazily in
>>> kvm_arch_sync_dirty_log (like x96 in the past).
>>>
>>
>> I think we need to rework the page fault handling on s390 to actually make
>> use of this. This has to happen anyway somewhen (as indicated by the guest
>> enter/exit rework from Mark). Right now we handle KVM page faults directly
>> in the normal system fault handler. It seems we need to make a side turn
>> into KVM for page faults on guests in the long run.
> 
> s390's page table management came up in conversation at KVM Forum in the context
> of a common MMU (or MMUs)[*].  If/when we get an MMU that supports multiple
> architectures, that would be a perfect opportunity for s390 to switch.  I don't
> know that it'll be feasible to make a common MMU support s390 from the get-go,
> but at the very least we can keep y'all in the loop and not make it unnecessarily
> difficult to support s390.
> 
> [*] https://urldefense.proofpoint.com/v2/url?u=https-3A__kvmforum2022.sched.com_event_15jJk&d=DwIDAw&c=s883GpUCOChKOHiocYtGcg&r=4hVFP4-J13xyn-OcN0apTCh8iKZRosf5OJTQePXBMB8&m=ea1RmNv-vQM3Ad3SEOr7EmyBdSD1qIFG_Vp8yROenZZFQWjn4Dm6CGaOpNE0LIeJ&s=GRTR1AntYFCoIjcd2GajoTeeek3nLNgmU2slGAbzSgI&e=
Thank you Sean for the reference to the KVM Forum talk. Should I skip 
the support for s390 (patch no. 4) for the next patchset?