Hi Alex,
On 10/07/2026 5:00 pm, Alexandru Elisei wrote:
Does it guarantee that, after it completes and returns to userspace, the
address range [gpa, gpa + size] is mapped in the VM's stage 2 tables? Or
does it guarantee that the address range was mapped at stage 2 at some
point during the ioctl's execution, but parts, or all of it, might not be
mapped after the ioctl completes and returns to userspace?
Nevermind, spend some time thinking about it and it turns out it's
impossible for KVM to guarantee that the memory is still mapped after the
ioctls returns. So I answered my own question, thanks.
Alex
Yeah it's best effort, as if a vCPU had faulted the range itself. This
could be undone by an invalidation or memslot update. The value is in
the common cast (for us, post-copy migration) the guest doesn't pay the
stage-2 fault fault cost at run time.
I think it would be worth me adding a sentence to the documentation
noting there is no persistance guarentee.
--
Thanks,
Jack
