From: Ingo Molnar <[email protected]>
Prevent the guest's loading of a corrupt cr3 (pointing at no guest phsyical
page) from crashing the host.
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Avi Kivity <[email protected]>
Index: linux-2.6/drivers/kvm/kvm_main.c
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm_main.c
+++ linux-2.6/drivers/kvm/kvm_main.c
@@ -463,7 +463,19 @@ void set_cr3(struct kvm_vcpu *vcpu, unsi
vcpu->cr3 = cr3;
spin_lock(&vcpu->kvm->lock);
- vcpu->mmu.new_cr3(vcpu);
+ /*
+ * Does the new cr3 value map to physical memory? (Note, we
+ * catch an invalid cr3 even in real-mode, because it would
+ * cause trouble later on when we turn on paging anyway.)
+ *
+ * A real CPU would silently accept an invalid cr3 and would
+ * attempt to use it - with largely undefined (and often hard
+ * to debug) behavior on the guest side.
+ */
+ if (unlikely(!gfn_to_memslot(vcpu->kvm, cr3 >> PAGE_SHIFT)))
+ inject_gp(vcpu);
+ else
+ vcpu->mmu.new_cr3(vcpu);
spin_unlock(&vcpu->kvm->lock);
}
EXPORT_SYMBOL_GPL(set_cr3);
-
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