arm/arm64: KVM: Take mmap_sem in stage2_unmap_vm

We don't hold the mmap_sem while searching for the VMAs when
we try to unmap each memslot for a VM. Fix this properly to
avoid unexpected results.

Fixes: commit 957db105c997 ("arm/arm64: KVM: Introduce stage2_unmap_vm")
Cc: stable@vger.kernel.org # v3.19+
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 962616fd4ddd..f2e2e0c6d6fd 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -803,6 +803,7 @@ void stage2_unmap_vm(struct kvm *kvm)
         int idx;
 
         idx = srcu_read_lock(&kvm->srcu);
+        down_read(&current->mm->mmap_sem);
         spin_lock(&kvm->mmu_lock);
 
         slots = kvm_memslots(kvm);
@@ -810,6 +811,7 @@ void stage2_unmap_vm(struct kvm *kvm)
                 stage2_unmap_memslot(kvm, memslot);
 
         spin_unlock(&kvm->mmu_lock);
+        up_read(&current->mm->mmap_sem);
         srcu_read_unlock(&kvm->srcu, idx);
 }