Commit 262b003d059c6671601a19057e9fe1a5e7f23722 upstream.

When registering a memslot, we check the size and location of that memslot against the IPA size to ensure that we can provide guest access to the whole of the memory.

Unfortunately, this check rejects memslot that end-up at the exact limit of the addressing capability for a given IPA size. For example, it refuses the creation of a 2GB memslot at 0x8000000 with a 32bit IPA space.

Fix it by relaxing the check to accept a memslot reaching the limit of the IPA space.

Fixes: c3058d5da222 ("arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE") Reviewed-by: Eric Auger eric.auger@redhat.com Signed-off-by: Marc Zyngier maz@kernel.org Cc: stable@vger.kernel.org # 4.4, 4.9, 4.14, 4.19 Reviewed-by: Andrew Jones drjones@redhat.com Link: https://lore.kernel.org/r/20210311100016.3830038-3-maz@kernel.org --- virt/kvm/arm/mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c index 787f7329d1b7..11103b75c596 100644 --- a/virt/kvm/arm/mmu.c +++ b/virt/kvm/arm/mmu.c @@ -2080,7 +2080,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, * Prevent userspace from creating a memory region outside of the IPA * space addressable by the KVM guest IPA space. */ - if (memslot->base_gfn + memslot->npages >= + if (memslot->base_gfn + memslot->npages > (KVM_PHYS_SIZE >> PAGE_SHIFT)) return -EFAULT;