1 files changed, 21 insertions, 0 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b4aac5c7ad87..631d2e544491 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1043,6 +1043,27 @@ static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
 {
         struct vcpu_svm *svm = to_svm(vcpu);
 
+        if (is_nested(svm)) {
+                /*
+                 * We are here because we run in nested mode, the host kvm
+                 * intercepts cr0 writes but the l1 hypervisor does not.
+                 * But the L1 hypervisor may intercept selective cr0 writes.
+                 * This needs to be checked here.
+                 */
+                unsigned long old, new;
+
+                /* Remove bits that would trigger a real cr0 write intercept */
+                old = vcpu->arch.cr0 & SVM_CR0_SELECTIVE_MASK;
+                new = cr0 & SVM_CR0_SELECTIVE_MASK;
+
+                if (old == new) {
+                        /* cr0 write with ts and mp unchanged */
+                        svm->vmcb->control.exit_code = SVM_EXIT_CR0_SEL_WRITE;
+                        if (nested_svm_exit_handled(svm) == NESTED_EXIT_DONE)
+                                return;
+                }
+        }
+
 #ifdef CONFIG_X86_64
         if (vcpu->arch.efer & EFER_LME) {
                 if (!is_paging(vcpu) && (cr0 & X86_CR0_PG)) {