[PATCH 2/4] KVM: nSVM: Check that DR6[63:32] and DR7[64:32] are not set on vmrun of nested guests

[Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>]

According to section "Canonicalization and Consistency Checks" in APM vol. 2
the following guest state is illegal:

    "DR6[63:32] are not zero."
    "DR7[63:32] are not zero."
    "Any MBZ bit of EFER is set."

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
---
 arch/x86/kvm/svm/nested.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 9a2a62e..2fec51d 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -208,6 +208,9 @@ static bool nested_vmcb_checks(struct vmcb *vmcb)
 	if ((vmcb->save.efer & EFER_SVME) == 0)
 		return false;
 
+	if (!kvm_dr6_valid(vmcb->save.dr6) || !kvm_dr7_valid(vmcb->save.dr7))
+		return false;
+
 	if ((vmcb->control.intercept & (1ULL << INTERCEPT_VMRUN)) == 0)
 		return false;
 
-- 
1.8.3.1