[PATCH RFC 05/10] KVM: Refactor kvm_handle_gfn_range() to avoid conditional mmu_lock
From: Marco Elver <elver@google.com>
Date: 2026-09-10 16:24:03
Also in:
kvm, lkml
Subsystem:
kernel virtual machine (kvm), the rest · Maintainers:
Paolo Bonzini, Linus Torvalds
Refactor kvm_handle_gfn_range() to check for overlapping memslots upfront via kvm_for_each_memslot_in_gfn_range() 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, eliminating the conditional locking and establishing a clean, unconditional lock scope for mmu_lock, which subsequently enables Clang context analysis to validate locking in this function. No functional change intended. Signed-off-by: Marco Elver <elver@google.com> --- virt/kvm/kvm_main.c | 46 +++++++++++++++++++++++++++++++++------------ 1 file changed, 34 insertions(+), 12 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f7bfa2d32507..f86e690a1798 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -2485,14 +2485,13 @@ bool kvm_range_has_memory_attributes(struct kvm *kvm, gfn_t start, gfn_t end, return true; } -static __always_inline void kvm_handle_gfn_range(struct kvm *kvm, - struct kvm_mmu_notifier_range *range) +static __always_inline bool __kvm_handle_gfn_range_walk(struct kvm *kvm, + struct kvm_mmu_notifier_range *range) { struct kvm_gfn_range gfn_range; struct kvm_memory_slot *slot; struct kvm_memslots *slots; struct kvm_memslot_iter iter; - bool found_memslot = false; bool ret = false; int i;
@@ -2519,22 +2518,45 @@ static __always_inline void kvm_handle_gfn_range(struct kvm *kvm, if (gfn_range.start >= gfn_range.end) continue; - if (!found_memslot) { - found_memslot = true; - KVM_MMU_LOCK(kvm); - if (!IS_KVM_NULL_FN(range->on_lock)) - range->on_lock(kvm); - } - ret |= range->handler(kvm, &gfn_range); } } + return ret; +} + +static __always_inline void kvm_handle_gfn_range(struct kvm *kvm, + struct kvm_mmu_notifier_range *range) +{ + struct kvm_memslot_iter iter; + struct kvm_memslots *slots; + bool found_memslot = false; + bool ret; + int i; + + for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { + slots = __kvm_memslots(kvm, i); + kvm_for_each_memslot_in_gfn_range(&iter, slots, range->start, range->end) { + found_memslot = true; + break; + } + if (found_memslot) + break; + } + + if (!found_memslot) + return; + + KVM_MMU_LOCK(kvm); + if (!IS_KVM_NULL_FN(range->on_lock)) + range->on_lock(kvm); + + ret = __kvm_handle_gfn_range_walk(kvm, range); + if (range->flush_on_ret && ret) kvm_flush_remote_tlbs(kvm); - if (found_memslot) - KVM_MMU_UNLOCK(kvm); + KVM_MMU_UNLOCK(kvm); } static bool kvm_pre_set_memory_attributes(struct kvm *kvm,
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2.55.0.1003.g10538fe699-goog