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Message-Id: <20240613122803.1031511-1-maobibo@loongson.cn> Date: Thu, 13 Jun 2024 20:28:03 +0800 From: Bibo Mao <maobibo@...ngson.cn> To: Paolo Bonzini <pbonzini@...hat.com> Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCH] KVM: Discard zero mask with function kvm_dirty_ring_reset Function kvm_reset_dirty_gfn may be called with parameters cur_slot / cur_offset / mask are all zero, it does not represent real dirty page. It is not necessary to clear dirty page in this condition. Also return value of macro __fls() is undefined if mask is zero which is called in funciton kvm_reset_dirty_gfn(). Here just discard it. Signed-off-by: Bibo Mao <maobibo@...ngson.cn> --- virt/kvm/dirty_ring.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/virt/kvm/dirty_ring.c b/virt/kvm/dirty_ring.c index 86d267db87bb..05f4c1c40cc7 100644 --- a/virt/kvm/dirty_ring.c +++ b/virt/kvm/dirty_ring.c @@ -147,14 +147,16 @@ int kvm_dirty_ring_reset(struct kvm *kvm, struct kvm_dirty_ring *ring) continue; } } - kvm_reset_dirty_gfn(kvm, cur_slot, cur_offset, mask); + if (mask) + kvm_reset_dirty_gfn(kvm, cur_slot, cur_offset, mask); cur_slot = next_slot; cur_offset = next_offset; mask = 1; first_round = false; } - kvm_reset_dirty_gfn(kvm, cur_slot, cur_offset, mask); + if (mask) + kvm_reset_dirty_gfn(kvm, cur_slot, cur_offset, mask); /* * The request KVM_REQ_DIRTY_RING_SOFT_FULL will be cleared base-commit: 83a7eefedc9b56fe7bfeff13b6c7356688ffa670 -- 2.39.3
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