[ 3.5.y.z extended stable ] Patch "KVM: Fix user memslot overlap check" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    KVM: Fix user memslot overlap check

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 081f1e643df0437576a6b99bc2858c3adf5ebab9 Mon Sep 17 00:00:00 2001
From: Alex Williamson <alex.williamson at redhat.com>
Date: Thu, 29 Nov 2012 14:07:59 -0700
Subject: [PATCH] KVM: Fix user memslot overlap check

commit 5419369ed6bd4cf711fdda5e52a5999b940413f5 upstream.

Prior to memory slot sorting this loop compared all of the user memory
slots for overlap with new entries.  With memory slot sorting, we're
just checking some number of entries in the array that may or may not
be user slots.  Instead, walk all the slots with kvm_for_each_memslot,
which has the added benefit of terminating early when we hit the first
empty slot, and skip comparison to private slots.

Signed-off-by: Alex Williamson <alex.williamson at redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti at redhat.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 virt/kvm/kvm_main.c |   13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 44ee712..7d9d969 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -689,8 +689,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	int r;
 	gfn_t base_gfn;
 	unsigned long npages;
-	unsigned long i;
-	struct kvm_memory_slot *memslot;
+	struct kvm_memory_slot *memslot, *slot;
 	struct kvm_memory_slot old, new;
 	struct kvm_memslots *slots, *old_memslots;

@@ -737,13 +736,11 @@ int __kvm_set_memory_region(struct kvm *kvm,

 	/* Check for overlaps */
 	r = -EEXIST;
-	for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
-		struct kvm_memory_slot *s = &kvm->memslots->memslots[i];
-
-		if (s == memslot || !s->npages)
+	kvm_for_each_memslot(slot, kvm->memslots) {
+		if (slot->id >= KVM_MEMORY_SLOTS || slot == memslot)
 			continue;
-		if (!((base_gfn + npages <= s->base_gfn) ||
-		      (base_gfn >= s->base_gfn + s->npages)))
+		if (!((base_gfn + npages <= slot->base_gfn) ||
+		      (base_gfn >= slot->base_gfn + slot->npages)))
 			goto out_free;
 	}

--
1.7.9.5