return true;
}
-static bool nested_vmcb_checks(struct vcpu_svm *svm, struct vmcb *vmcb12)
+static bool nested_vmcb_check_save(struct vcpu_svm *svm, struct vmcb *vmcb12)
{
struct kvm_vcpu *vcpu = &svm->vcpu;
bool vmcb12_lma;
+ /*
+ * FIXME: these should be done after copying the fields,
+ * to avoid TOC/TOU races. For these save area checks
+ * the possible damage is limited since kvm_set_cr0 and
+ * kvm_set_cr4 handle failure; EFER_SVME is an exception
+ * so it is force-set later in nested_prepare_vmcb_save.
+ */
if ((vmcb12->save.efer & EFER_SVME) == 0)
return false;
if (!kvm_is_valid_cr4(&svm->vcpu, vmcb12->save.cr4))
return false;
- return nested_vmcb_check_controls(&vmcb12->control);
+ return true;
}
static void load_nested_vmcb_control(struct vcpu_svm *svm,
svm->vmcb->save.gdtr = vmcb12->save.gdtr;
svm->vmcb->save.idtr = vmcb12->save.idtr;
kvm_set_rflags(&svm->vcpu, vmcb12->save.rflags | X86_EFLAGS_FIXED);
- svm_set_efer(&svm->vcpu, vmcb12->save.efer);
+
+ /*
+ * Force-set EFER_SVME even though it is checked earlier on the
+ * VMCB12, because the guest can flip the bit between the check
+ * and now. Clearing EFER_SVME would call svm_free_nested.
+ */
+ svm_set_efer(&svm->vcpu, vmcb12->save.efer | EFER_SVME);
+
svm_set_cr0(&svm->vcpu, vmcb12->save.cr0);
svm_set_cr4(&svm->vcpu, vmcb12->save.cr4);
svm->vmcb->save.cr2 = svm->vcpu.arch.cr2 = vmcb12->save.cr2;
svm->nested.vmcb12_gpa = vmcb12_gpa;
- load_nested_vmcb_control(svm, &vmcb12->control);
nested_prepare_vmcb_control(svm);
nested_prepare_vmcb_save(svm, vmcb12);
if (WARN_ON_ONCE(!svm->nested.initialized))
return -EINVAL;
- if (!nested_vmcb_checks(svm, vmcb12)) {
+ load_nested_vmcb_control(svm, &vmcb12->control);
+
+ if (!nested_vmcb_check_save(svm, vmcb12) ||
+ !nested_vmcb_check_controls(&svm->nested.ctl)) {
vmcb12->control.exit_code = SVM_EXIT_ERR;
vmcb12->control.exit_code_hi = 0;
vmcb12->control.exit_info_1 = 0;
*/
if (!(save->cr0 & X86_CR0_PG))
goto out_free;
+ if (!(save->efer & EFER_SVME))
+ goto out_free;
/*
* All checks done, we can enter guest mode. L1 control fields