From: Sean Christopherson <seanjc@xxxxxxxxxx>
Stop making a full copy of the old memslot in __kvm_set_memory_region()
now that metadata updates are handled by kvm_set_memslot(), i.e. now that
the old memslot's dirty bitmap doesn't need to be referenced after the
memslot and its pointer is modified/invalidated by kvm_set_memslot().
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
---
virt/kvm/kvm_main.c | 35 +++++++++++++----------------------
1 file changed, 13 insertions(+), 22 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1689f598fe9e..1f37c4ce5f97 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1732,8 +1732,8 @@ static int kvm_set_memslot(struct kvm *kvm,
int __kvm_set_memory_region(struct kvm *kvm,
const struct kvm_userspace_memory_region *mem)
{
- struct kvm_memory_slot old, new;
- struct kvm_memory_slot *tmp;
+ struct kvm_memory_slot *old, *tmp;
+ struct kvm_memory_slot new;
enum kvm_mr_change change;
int as_id, id;
int r;
@@ -1763,25 +1763,16 @@ int __kvm_set_memory_region(struct kvm *kvm,
return -EINVAL;
/*
- * Make a full copy of the old memslot, the pointer will become stale
- * when the memslots are re-sorted by update_memslots(), and the old
- * memslot needs to be referenced after calling update_memslots(), e.g.
- * to free its resources and for arch specific behavior.
+ * Note, the old memslot (and the pointer itself!) may be invalidated
+ * and/or destroyed by kvm_set_memslot().
*/
- tmp = id_to_memslot(__kvm_memslots(kvm, as_id), id);
- if (tmp) {
- old = *tmp;
- tmp = NULL;
- } else {
- memset(&old, 0, sizeof(old));
- old.id = id;
- }
+ old = id_to_memslot(__kvm_memslots(kvm, as_id), id);
if (!mem->memory_size) {
- if (!old.npages)
+ if (!old || !old->npages)
return -EINVAL;
- if (WARN_ON_ONCE(kvm->nr_memslot_pages < old.npages))
+ if (WARN_ON_ONCE(kvm->nr_memslot_pages < old->npages))
return -EIO;
memset(&new, 0, sizeof(new));
@@ -1801,7 +1792,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
if (new.npages > KVM_MEM_MAX_NR_PAGES)
return -EINVAL;
- if (!old.npages) {
+ if (!old || !old->npages) {
change = KVM_MR_CREATE;
/*
@@ -1811,14 +1802,14 @@ int __kvm_set_memory_region(struct kvm *kvm,
if ((kvm->nr_memslot_pages + new.npages) < kvm->nr_memslot_pages)
return -EINVAL;
} else { /* Modify an existing slot. */
- if ((new.userspace_addr != old.userspace_addr) ||
- (new.npages != old.npages) ||
- ((new.flags ^ old.flags) & KVM_MEM_READONLY))
+ if ((new.userspace_addr != old->userspace_addr) ||
+ (new.npages != old->npages) ||
+ ((new.flags ^ old->flags) & KVM_MEM_READONLY))
return -EINVAL;
- if (new.base_gfn != old.base_gfn)
+ if (new.base_gfn != old->base_gfn)
change = KVM_MR_MOVE;
- else if (new.flags != old.flags)
+ else if (new.flags != old->flags)
change = KVM_MR_FLAGS_ONLY;
else /* Nothing to change. */
return 0;
