[PATCH 23/27] KVM: x86/mmu: Bug the VM if write-tracking is used but not enabled

Sean Christopherson
2022-12-23T01:01:05Z

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.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/page_track.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c
index 209f6beba5ac..d4c3bd6642b3 100644
--- a/arch/x86/kvm/mmu/page_track.c
+++ b/arch/x86/kvm/mmu/page_track.c
@@ -89,7 +89,7 @@ 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(!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);
@@ -121,7 +121,7 @@ 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(!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);
--
2.39.0.314.g84b9a713c41-goog