- vmcs_writel(CR0_READ_SHADOW, cr0);
- vmcs_writel(GUEST_CR0, hw_cr0);
- vcpu->arch.cr0 = cr0;
- kvm_register_mark_available(vcpu, VCPU_EXREG_CR0);
+ /*
+ * When running with EPT but not unrestricted guest, KVM must
+ * intercept CR3 accesses when paging is _disabled_. This is
+ * necessary because restricted guests can't actually run with
+ * paging disabled, and so KVM stuffs its own CR3 in order to
+ * run the guest when identity mapped page tables.
+ *
+ * Do _NOT_ check the old CR0.PG, e.g. to optimize away the
+ * update, it may be stale with respect to CR3 interception,
+ * e.g. after nested VM-Enter.
+ *
+ * Lastly, honor L1's desires, i.e. intercept CR3 loads and/or
+ * stores to forward them to L1, even if KVM does not need to
+ * intercept them to preserve its identity mapped page tables.
+ */
+ if (!(cr0 & X86_CR0_PG)) {
+ exec_controls_setbit(vmx, CR3_EXITING_BITS);
+ } else if (!is_guest_mode(vcpu)) {
+ exec_controls_clearbit(vmx, CR3_EXITING_BITS);
+ } else {
+ tmp = exec_controls_get(vmx);
+ tmp &= ~CR3_EXITING_BITS;
+ tmp |= get_vmcs12(vcpu)->cpu_based_vm_exec_control & CR3_EXITING_BITS;
+ exec_controls_set(vmx, tmp);
+ }
+
+ /* Note, vmx_set_cr4() consumes the new vcpu->arch.cr0. */
+ if ((old_cr0_pg ^ cr0) & X86_CR0_PG)
+ vmx_set_cr4(vcpu, kvm_read_cr4(vcpu));
+ }