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?
