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Peter Anvin" , Vitaly Kuznetsov , Kiryl Shutsemau , Rick Edgecombe , David Hildenbrand , kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Thu, Sep 10, 2026, Marco Elver wrote: > Refactor kvm_handle_hva_range() to check for overlapping memslots > upfront via interval_tree_iter_first() instead of tracking found > memslots inside the range iteration with a 'found_memslot' flag and > conditionally acquiring and releasing mmu_lock. > > This simplifies the control flow by cleanly decoupling the search for > overlapping memslots from the subsequent walk. It also separates the > lockless path from the serialized path into distinct branches, > eliminating the conditional locking, which subsequently enables Clang > context analysis to validate locking in this function. At the cost of duplicating code and adding overhead when there is a relevant memslot. I'm not wedded to the exact implementation, but IMO this is not at all an improvement. Without a clear explanation of what value is added by enabling Clang to "validate locking", I don't see any justificatoin for the change. > No functional change intended. > > Signed-off-by: Marco Elver > --- > virt/kvm/kvm_main.c | 94 ++++++++++++++++++++++++++++----------------- > 1 file changed, 58 insertions(+), 36 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 65eb26a0520d..f7bfa2d32507 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -558,31 +558,14 @@ static void kvm_null_fn(void) > node; \ > node = interval_tree_iter_next(node, start, last)) \ > > -static __always_inline kvm_mn_ret_t kvm_handle_hva_range(struct kvm *kvm, > - const struct kvm_mmu_notifier_range *range) > +static __always_inline bool __kvm_handle_hva_range_walk(struct kvm *kvm, > + const struct kvm_mmu_notifier_range *range) > { > - struct kvm_mmu_notifier_return r = { > - .ret = false, > - .found_memslot = false, > - }; > struct kvm_gfn_range gfn_range; > struct kvm_memory_slot *slot; > struct kvm_memslots *slots; > - int i, idx; > - > - if (WARN_ON_ONCE(range->end <= range->start)) > - return r; > - > - /* A null handler is allowed if and only if on_lock() is provided. */ > - if (WARN_ON_ONCE(IS_KVM_NULL_FN(range->on_lock) && > - IS_KVM_NULL_FN(range->handler))) > - return r; > - > - /* on_lock will never be called for lockless walks */ > - if (WARN_ON_ONCE(range->lockless && !IS_KVM_NULL_FN(range->on_lock))) > - return r; > - > - idx = srcu_read_lock(&kvm->srcu); > + bool ret = false; > + int i; > > for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { > struct interval_tree_node *node; > @@ -620,28 +603,67 @@ static __always_inline kvm_mn_ret_t kvm_handle_hva_range(struct kvm *kvm, > gfn_range.slot = slot; > gfn_range.lockless = range->lockless; > > - if (!r.found_memslot) { > - r.found_memslot = true; > - if (!range->lockless) { > - KVM_MMU_LOCK(kvm); > - if (!IS_KVM_NULL_FN(range->on_lock)) > - range->on_lock(kvm); > + ret |= range->handler(kvm, &gfn_range); > + } > + } > + > + return ret; > +} > > - if (IS_KVM_NULL_FN(range->handler)) > - goto mmu_unlock; > - } > - } > - r.ret |= range->handler(kvm, &gfn_range); > +static __always_inline kvm_mn_ret_t kvm_handle_hva_range(struct kvm *kvm, > + const struct kvm_mmu_notifier_range *range) > +{ > + struct kvm_mmu_notifier_return r = { > + .ret = false, > + .found_memslot = false, > + }; > + struct kvm_memslots *slots; > + int i, idx; > + > + if (WARN_ON_ONCE(range->end <= range->start)) > + return r; > + > + /* A null handler is allowed if and only if on_lock() is provided. */ > + if (WARN_ON_ONCE(IS_KVM_NULL_FN(range->on_lock) && > + IS_KVM_NULL_FN(range->handler))) > + return r; > + > + /* on_lock will never be called for lockless walks */ > + if (WARN_ON_ONCE(range->lockless && !IS_KVM_NULL_FN(range->on_lock))) > + return r; > + > + idx = srcu_read_lock(&kvm->srcu); > + > + for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { > + slots = __kvm_memslots(kvm, i); > + if (interval_tree_iter_first(&slots->hva_tree, range->start, range->end - 1)) { > + r.found_memslot = true; > + break; > } > } > > - if (range->flush_on_ret && r.ret) > - kvm_flush_remote_tlbs(kvm); > + if (!r.found_memslot) > + goto out; > + > + if (range->lockless) { > + r.ret = __kvm_handle_hva_range_walk(kvm, range); > + if (range->flush_on_ret && r.ret) > + kvm_flush_remote_tlbs(kvm); > + } else { > + KVM_MMU_LOCK(kvm); > + if (!IS_KVM_NULL_FN(range->on_lock)) > + range->on_lock(kvm); > + > + if (!IS_KVM_NULL_FN(range->handler)) > + r.ret = __kvm_handle_hva_range_walk(kvm, range); > + > + if (range->flush_on_ret && r.ret) > + kvm_flush_remote_tlbs(kvm); > > -mmu_unlock: > - if (r.found_memslot && !range->lockless) > KVM_MMU_UNLOCK(kvm); > + } > > +out: > srcu_read_unlock(&kvm->srcu, idx); > > return r; > -- > 2.55.0.1003.g10538fe699-goog >