When the live migration of a confidential guest is cancelled, ram save
needs to be cancelled with some vendor specific work required (e.g.
restore some private pages's state). Here are 3 cases:
If the migration cancelling request is received before ram saving
starts (i.e. cgs_epochs is 0), nothing needs to be done;
If the migration cancelling request is received during the first round
of ram saving, provide the vendor specific handling via the cgs_mig API
with the gfn of the last page that has been saved; and
If the migration cancelling request is received after the first round of
ram saving, it is likely all the pages have been saved. The gfn of the
last page is set to the end of the guest ram page.
As clearing the KVM's bitmap write-protects the private pages in chunks
(e.g. 256K pages by default), so the end_gfn needs to be aligned to the
chunk boundary.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
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