KVM: x86/mmu: Bug the VM if write-tracking is used but not enabled

Bug the VM if something attempts to write-track a gfn, but write-tracking
isn't enabled.  The VM is doomed (and KVM has an egregious bug) if KVM or
KVMGT wants to shadow guest page tables but can't because write-tracking
isn't enabled.

Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20230729013535.1070024-27-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c
index 2c6b912..9bf0131 100644 (file)
--- a/arch/x86/kvm/mmu/page_track.c
+++ b/arch/x86/kvm/mmu/page_track.c
@@ -90,7 +90,7 @@ void kvm_write_track_add_gfn(struct kvm *kvm, struct kvm_memory_slot *slot,
        lockdep_assert_once(lockdep_is_held(&kvm->slots_lock) ||
                            srcu_read_lock_held(&kvm->srcu));
 
-       if (WARN_ON_ONCE(!kvm_page_track_write_tracking_enabled(kvm)))
+       if (KVM_BUG_ON(!kvm_page_track_write_tracking_enabled(kvm), kvm))
                return;
 
        update_gfn_write_track(slot, gfn, 1);
@@ -122,7 +122,7 @@ void kvm_write_track_remove_gfn(struct kvm *kvm,
        lockdep_assert_once(lockdep_is_held(&kvm->slots_lock) ||
                            srcu_read_lock_held(&kvm->srcu));
 
-       if (WARN_ON_ONCE(!kvm_page_track_write_tracking_enabled(kvm)))
+       if (KVM_BUG_ON(!kvm_page_track_write_tracking_enabled(kvm), kvm))
                return;
 
        update_gfn_write_track(slot, gfn, -1);