@@ -215,24 +215,6 @@ static bool nested_svm_vmrun_msrpm(struct vcpu_svm *svm)
return true;
}
-static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu)
-{
- struct vcpu_svm *svm = to_svm(vcpu);
-
- if (WARN_ON(!is_guest_mode(vcpu)))
- return true;
-
- if (!nested_svm_vmrun_msrpm(svm)) {
- vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
- vcpu->run->internal.suberror =
- KVM_INTERNAL_ERROR_EMULATION;
- vcpu->run->internal.ndata = 0;
- return false;
- }
-
- return true;
-}
-
static bool nested_vmcb_check_controls(struct vmcb_control_area *control)
{
if (CC(!vmcb_is_intercept(control, INTERCEPT_VMRUN)))
@@ -1311,6 +1293,28 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
return ret;
}
+static bool svm_get_nested_state_pages(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ if (WARN_ON(!is_guest_mode(vcpu)))
+ return true;
+
+ if (nested_svm_load_cr3(&svm->vcpu, vcpu->arch.cr3,
+ nested_npt_enabled(svm)))
+ return false;
+
+ if (!nested_svm_vmrun_msrpm(svm)) {
+ vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+ vcpu->run->internal.suberror =
+ KVM_INTERNAL_ERROR_EMULATION;
+ vcpu->run->internal.ndata = 0;
+ return false;
+ }
+
+ return true;
+}
+
struct kvm_x86_nested_ops svm_nested_ops = {
.check_events = svm_check_nested_events,
.get_nested_state_pages = svm_get_nested_state_pages,
While KVM's MMU should be fully reset by loading of nested CR0/CR3/CR4 by KVM_SET_SREGS, we are not in nested mode yet when we do it and therefore only root_mmu is reset. On regular nested entries we call nested_svm_load_cr3 which both updates the guest's CR3 in the MMU when it is needed, and it also initializes the mmu again which makes it initialize the walk_mmu as well when nested paging is enabled in both host and guest. Since we don't call nested_svm_load_cr3 on nested state load, the walk_mmu can be left uninitialized, which can lead to a NULL pointer dereference while accessing it, if we happen to get a nested page fault right after entering the nested guest first time after the migration and if we decide to emulate it. This makes the emulator access NULL walk_mmu->gva_to_gpa. Therefore we should call this function on nested state load as well. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> --- arch/x86/kvm/svm/nested.c | 40 +++++++++++++++++++++------------------ 1 file changed, 22 insertions(+), 18 deletions(-)