KVM: VMX: Check cpl before emulating debug register access
Debug registers may only be accessed from cpl 0. Unfortunately, vmx will
code to emulate the instruction even though it was issued from guest
userspace, possibly leading to an unexpected trap later.
Cc: stable@kernel.org
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7627ff6..4137cc5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -223,6 +223,19 @@
EXPORT_SYMBOL_GPL(kvm_queue_exception_e);
/*
+ * Checks if cpl <= required_cpl; if true, return true. Otherwise queue
+ * a #GP and return false.
+ */
+bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl)
+{
+ if (kvm_x86_ops->get_cpl(vcpu) <= required_cpl)
+ return true;
+ kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
+ return false;
+}
+EXPORT_SYMBOL_GPL(kvm_require_cpl);
+
+/*
* Load the pae pdptrs. Return true is they are all valid.
*/
int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)