[RFC PATCH 8/9] kvm_main.c: find memslots from the inactive memslot list

Emanuele Giuseppe Esposito
2022-09-09T10:45:37Z

Instead of looking at the active list, look at the inactive.
This causes no harm to the current code, as active and inactive
lists are identical at this point.

In addition, provide flexibility for atomic memslot
updates, because in that case we want to perform multiple
updates in the inactive list first, and then perform a single
swap only. If we were to use the active list, previous updates
that were not yet swapped won't be seen, and the following logic
in kvm_prepare_batch() could for example find an old memslot
that was deleted in the inactive but not in the active, thus
wrongly assuming that the coming request is a MOVE and not a CREATE.

Note that this also causes no harm to the invalidate memslot, since
we are already inserting it as replacement in both active and inactive
list.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
virt/kvm/kvm_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 31e46f9a06fa..ecd43560281c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1948,7 +1948,7 @@ static int kvm_prepare_batch(struct kvm *kvm,
as_id = mem->slot >> 16;
id = (u16)mem->slot;

- slots = __kvm_memslots(kvm, as_id);
+ slots = kvm_get_inactive_memslots(kvm, as_id);

/*
* Note, the old memslot (and the pointer itself!) may be invalidated
--
2.31.1