On 02/02/21 19:57, Ben Gardon wrote:
@@ -720,7 +790,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
*/
if (is_shadow_present_pte(iter.old_spte) &&
is_large_pte(iter.old_spte)) {
- tdp_mmu_set_spte(vcpu->kvm, &iter, 0);
+ if (!tdp_mmu_set_spte_atomic(vcpu->kvm, &iter, 0))
+ break;
kvm_flush_remote_tlbs_with_address(vcpu->kvm, iter.gfn,
KVM_PAGES_PER_HPAGE(iter.level));
/*
* The iter must explicitly re-read the spte here
* because the new value informs the !present
* path below.
*/
iter.old_spte = READ_ONCE(*rcu_dereference(iter.sptep));
}
if (!is_shadow_present_pte(iter.old_spte)) {
Would it be easier to reason about this code by making it retry, like:
retry:
if (is_shadow_present_pte(iter.old_spte)) {
if (is_large_pte(iter.old_spte)) {
if (!tdp_mmu_zap_spte_atomic(vcpu->kvm, &iter))
break;
/*
* The iter must explicitly re-read the SPTE because
* the atomic cmpxchg failed.
*/
iter.old_spte = READ_ONCE(*rcu_dereference(iter.sptep));
goto retry;
}
} else {
...
}
?
Paolo
