Hi Jack, On Thu, Sep 11, 2025 at 02:46:42PM +0100, Jack Thomson wrote: > From: Jack Thomson <[email protected]> > > Overview: > > This patch series adds ARM64 support for the KVM_PRE_FAULT_MEMORY > feature, which was previously only available on x86 [1]. This allows > a reduction in the number of stage-2 faults during execution. This is > beneficial in post-copy migration scenarios, particularly in memory > intensive applications, where high latencies are experienced due to > the stage-2 faults when pre-populating memory via UFFD / memcpy.
Thanks for posting the series. More of a general comment on the UAPI documentation: "... However, KVM does not mark any newly created stage-2 PTE as Accessed." This behavior is x86-specific since kvm_pgtable_stage2_map() will lay down PTEs with the AF set. Probably shouldn't have documented the internal state of the stage-2 in the first place but oh well, please just update the UAPI description to make it clear this is x86-specific. Thanks Oliver
