From: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Date: Fri, 11 Jan 2013 09:26:55 +0000 (+0900)
Subject: KVM: set_memory_region: Don't check for overlaps unless we create or move a slot
X-Git-Tag: firefly_0821_release~3680^2~569^2~181
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=0a706beefb1de71bf8551f9860dc529ef14d6753;p=firefly-linux-kernel-4.4.55.git

KVM: set_memory_region: Don't check for overlaps unless we create or move a slot

Don't need the check for deleting an existing slot or just modifiying
the flags.

Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
---

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 28eb160fd487..fca64879f967 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -782,14 +782,16 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	if (!npages && !old.npages)
 		goto out;
 
-	/* Check for overlaps */
-	r = -EEXIST;
-	kvm_for_each_memslot(slot, kvm->memslots) {
-		if (slot->id >= KVM_USER_MEM_SLOTS || slot == memslot)
-			continue;
-		if (!((base_gfn + npages <= slot->base_gfn) ||
-		      (base_gfn >= slot->base_gfn + slot->npages)))
-			goto out;
+	if ((npages && !old.npages) || (base_gfn != old.base_gfn)) {
+		/* Check for overlaps */
+		r = -EEXIST;
+		kvm_for_each_memslot(slot, kvm->memslots) {
+			if (slot->id >= KVM_USER_MEM_SLOTS || slot == memslot)
+				continue;
+			if (!((base_gfn + npages <= slot->base_gfn) ||
+			      (base_gfn >= slot->base_gfn + slot->npages)))
+				goto out;
+		}
 	}
 
 	/* Free page dirty bitmap if unneeded */