[PATCH 03/13] KVM: WARN if *any* MMU invalidation sequence doesn't add a range

Sean Christopherson
2023-09-21T21:43:34Z

Tweak the assertion in kvm_mmu_invalidate_end() to unconditionally require
a range to be added between start() and end(). Asserting if and only if
kvm->mmu_invalidate_in_progress is non-zero makes the assertion all but
useless as it would fire only when there are multiple invalidations in
flight, which is not common and would also get a false negative if one or
more sequences, but not all, added a range.

Reported-by: Binbin Wu <binbin.wu@linux.intel.com>
Fixes: 145725d1542a ("KVM: Use gfn instead of hva for mmu_notifier_retry")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
virt/kvm/kvm_main.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 30708e460568..54480655bcce 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -873,11 +873,10 @@ void kvm_mmu_invalidate_end(struct kvm *kvm)
KVM_BUG_ON(kvm->mmu_invalidate_in_progress < 0, kvm);

/*
- * Assert that at least one range must be added between start() and
- * end(). Not adding a range isn't fatal, but it is a KVM bug.
+ * Assert that at least one range was added between start() and end().
+ * Not adding a range isn't fatal, but it is a KVM bug.
*/
- WARN_ON_ONCE(kvm->mmu_invalidate_in_progress &&
- kvm->mmu_invalidate_range_start == INVALID_GPA);
+ WARN_ON_ONCE(kvm->mmu_invalidate_range_start == INVALID_GPA);
}

static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
--
2.42.0.515.g380fc7ccd1-goog