From nobody Mon Jun 8 04:25:46 2026 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C7B87134CF for ; Tue, 2 Jun 2026 04:32:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.3 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780374753; cv=none; b=A3sIWTPFk48KmIw9QiAfXUbGFB8MoggTIZ1Zk7H3U1jFiJImJCu/8zTH+EsVJC6Ue/HW0rWfVdUPoKWIliaVu5G3swrU4XsLgK/KytBQSe4/fc2Q60WNybuBzuQJE3N9WsYsNh3gYhzPRG6PY6cZ5xc4Cu0h9HFDqRmsdGSpO/U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780374753; c=relaxed/simple; bh=2Y6n5vptl+UQKIOpJvWwgsp4V3dO0ej51oIaDqxEORY=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Type; b=jHUSc6JoVqaudEAvtq5JAM5jMUoOIOJVPpExmgIjQJk6n9rKNdvgoohDjPCRMViGIgbyfgXwLogR6BOgK9QWhw3mEamVmA8NwQE/enZIkWvCv1crfYAnldtwLSEjYwz3KhLcIi+XrQFrsgITV8JD0segEz1xBk3Zho25pUCoBzw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=SGxNI7I7; arc=none smtp.client-ip=220.197.31.3 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="SGxNI7I7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-Id:MIME-Version: Content-Type; bh=fjVGfXcKNG+YTxVcw+/rYcl97WsmjmXNVuWfW4kOW6Y=; b=SGxNI7I7a2Pau4wEoeTi/3AjccHY9VDLQ+oTuceAE+LhOxOwvip9pexQu0BlCW D+mF1T2sZRg+UZU0XI32gf9hGeBRVj2eKsv84T7d94vsLsy95miOIVt537Ms95Bg qN9Jo4AQt0maDJJiiI9eTAeoohWg/uphxe8czh3UvfZlw= Received: from yangjl.localdomain (unknown []) by gzga-smtp-mtada-g0-2 (Coremail) with SMTP id _____wAn0+fDXB5qSNGwAw--.28891S2; Tue, 02 Jun 2026 12:32:04 +0800 (CST) From: yangjiale To: "Michael S . Tsirkin" Cc: Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, yangjiale Subject: [PATCH] VIRTIO: Update the desc 'flag' fied last in packed ring. Date: Tue, 2 Jun 2026 12:31:23 +0800 Message-Id: <20260602043123.10207-1-yangjiale133@163.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _____wAn0+fDXB5qSNGwAw--.28891S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7uFykZry8GF4xCF1xCFy7GFg_yoW8GFW7pF 4Ykay5C3WfZF12qanrGF17WFy5u3s3K34fZayUW34Y9F15ZF17Xry0kFyxtr4UJryvyw48 Ar4xuayUGF1kuFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0zEiL0-UUUUU= X-CM-SenderInfo: p1dqwy5ldoviitt6il2tof0z/xtbC-gRqg2oeXMQlMQAA3r When a descriptor list spans across cache lines, updating the flag first can lead to a scenario where the device side perceives the flag as valid, yet the corresponding address and length fields remain unupdated=E2=80=94resulting in invalid values. Therefore, the flag field must be updated last. Signed-off-by: yangjiale --- drivers/virtio/virtio_ring.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index fbca7ce1c6bf..036b4f90d30f 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -1688,6 +1688,10 @@ static inline int virtqueue_add_packed(struct vring_= virtqueue *vq, &addr, &len, premapped, attr)) goto unmap_release; =20 + desc[i].addr =3D cpu_to_le64(addr); + desc[i].len =3D cpu_to_le32(len); + desc[i].id =3D cpu_to_le16(id); + flags =3D cpu_to_le16(vq->packed.avail_used_flags | (++c =3D=3D total_sg ? 0 : VRING_DESC_F_NEXT) | (n < out_sgs ? 0 : VRING_DESC_F_WRITE)); @@ -1696,10 +1700,6 @@ static inline int virtqueue_add_packed(struct vring_= virtqueue *vq, else desc[i].flags =3D flags; =20 - desc[i].addr =3D cpu_to_le64(addr); - desc[i].len =3D cpu_to_le32(len); - desc[i].id =3D cpu_to_le16(id); - if (unlikely(vq->use_map_api)) { vq->packed.desc_extra[curr].addr =3D premapped ? DMA_MAPPING_ERROR : addr; --=20 2.25.1