KVM: Fix user memslot overlap check (5419369e) · Commits · 戴 / test

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. Cc: stable@vger.kernel.org Signed-off-by:

Alex Williamson <alex.williamson@redhat.com> Signed-off-by:

Marcelo Tosatti <mtosatti@redhat.com>

virt/kvm/kvm_main.c

+5 −8

Original line number	Diff line number	Diff line
		@@ -714,8 +714,7 @@ 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;

		@@ -766,13 +765,11 @@ 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;
		}

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