Re: [PATCH v4 00/10] KVM: nVMX: Improve performance for unmanaged guest memory

[Sean Christopherson]

On Fri, Jan 02, 2026, Fred Griffoul wrote:
> First, the current approach is missing proper invalidation handling in
> critical scenarios. Enlightened VMCS (eVMCS) pages can become stale when
> memslots are modified, as there is no mechanism to invalidate the cached
> mappings.

This is a non-issue.  Modifying memslots while vCPUs are active will cause problems,
period.  There is no magic on earth that will prevent that.

> Similarly, APIC access and virtual APIC pages can be migrated
> by the host, but without proper notification through mmu_notifier
> callbacks, the mappings become invalid and can lead to incorrect
> behavior.

No, they can't, at least not for unmanaged memory.  For kernel-managed memory,
KVM obtains a long-term pin, which prevents the host from migrating the page.