From nobody Sat Apr 11 02:20:01 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E576C28B2B for ; Wed, 17 Aug 2022 13:59:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236634AbiHQN7t (ORCPT ); Wed, 17 Aug 2022 09:59:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46442 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239884AbiHQN7V (ORCPT ); Wed, 17 Aug 2022 09:59:21 -0400 Received: from smtp236.sjtu.edu.cn (smtp236.sjtu.edu.cn [202.120.2.236]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6527589917; Wed, 17 Aug 2022 06:59:11 -0700 (PDT) Received: from proxy02.sjtu.edu.cn (smtp188.sjtu.edu.cn [202.120.2.188]) by smtp236.sjtu.edu.cn (Postfix) with ESMTPS id 9A62A1008B38F; Wed, 17 Aug 2022 21:58:48 +0800 (CST) Received: from localhost (localhost.localdomain [127.0.0.1]) by proxy02.sjtu.edu.cn (Postfix) with ESMTP id 052AA2009BEAD; Wed, 17 Aug 2022 21:58:48 +0800 (CST) X-Virus-Scanned: amavisd-new at Received: from proxy02.sjtu.edu.cn ([127.0.0.1]) by localhost (proxy02.sjtu.edu.cn [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id 9ZmfqEkD5H1c; Wed, 17 Aug 2022 21:58:47 +0800 (CST) Received: from localhost.localdomain (unknown [202.120.40.82]) (Authenticated sender: qtxuning1999@sjtu.edu.cn) by proxy02.sjtu.edu.cn (Postfix) with ESMTPSA id EB8352009BEA0; Wed, 17 Aug 2022 21:58:35 +0800 (CST) From: Guo Zhi To: eperezma@redhat.com, jasowang@redhat.com, sgarzare@redhat.com, mst@redhat.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, Guo Zhi Subject: [RFC v2 6/7] virtio: in order support for virtio_ring Date: Wed, 17 Aug 2022 21:57:17 +0800 Message-Id: <20220817135718.2553-7-qtxuning1999@sjtu.edu.cn> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220817135718.2553-1-qtxuning1999@sjtu.edu.cn> References: <20220817135718.2553-1-qtxuning1999@sjtu.edu.cn> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" If in order feature negotiated, we can skip the used ring to get buffer's desc id sequentially. Signed-off-by: Guo Zhi --- drivers/virtio/virtio_ring.c | 53 ++++++++++++++++++++++++++++++------ 1 file changed, 45 insertions(+), 8 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 1c1b3fa376a2..143184ebb5a1 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -144,6 +144,9 @@ struct vring_virtqueue { /* DMA address and size information */ dma_addr_t queue_dma_addr; size_t queue_size_in_bytes; + + /* In order feature batch begin here */ + u16 next_desc_begin; } split; =20 /* Available for packed ring */ @@ -702,8 +705,13 @@ static void detach_buf_split(struct vring_virtqueue *v= q, unsigned int head, } =20 vring_unmap_one_split(vq, i); - vq->split.desc_extra[i].next =3D vq->free_head; - vq->free_head =3D head; + /* In order feature use desc in order, + * that means, the next desc will always be free + */ + if (!virtio_has_feature(vq->vq.vdev, VIRTIO_F_IN_ORDER)) { + vq->split.desc_extra[i].next =3D vq->free_head; + vq->free_head =3D head; + } =20 /* Plus final descriptor */ vq->vq.num_free++; @@ -745,7 +753,7 @@ static void *virtqueue_get_buf_ctx_split(struct virtque= ue *_vq, { struct vring_virtqueue *vq =3D to_vvq(_vq); void *ret; - unsigned int i; + unsigned int i, j; u16 last_used; =20 START_USE(vq); @@ -764,11 +772,38 @@ static void *virtqueue_get_buf_ctx_split(struct virtq= ueue *_vq, /* Only get used array entries after they have been exposed by host. */ virtio_rmb(vq->weak_barriers); =20 - last_used =3D (vq->last_used_idx & (vq->split.vring.num - 1)); - i =3D virtio32_to_cpu(_vq->vdev, - vq->split.vring.used->ring[last_used].id); - *len =3D virtio32_to_cpu(_vq->vdev, - vq->split.vring.used->ring[last_used].len); + if (virtio_has_feature(_vq->vdev, VIRTIO_F_IN_ORDER)) { + /* Skip used ring and get used desc in order*/ + i =3D vq->split.next_desc_begin; + j =3D i; + /* Indirect only takes one descriptor in descriptor table */ + while (!vq->indirect && (vq->split.desc_extra[j].flags & VRING_DESC_F_NE= XT)) + j =3D (j + 1) % vq->split.vring.num; + /* move to next */ + j =3D (j + 1) % vq->split.vring.num; + /* Next buffer will use this descriptor in order */ + vq->split.next_desc_begin =3D j; + if (!vq->indirect) { + *len =3D vq->split.desc_extra[i].len; + } else { + struct vring_desc *indir_desc =3D + vq->split.desc_state[i].indir_desc; + u32 indir_num =3D vq->split.desc_extra[i].len, buffer_len =3D 0; + + if (indir_desc) { + for (j =3D 0; j < indir_num / sizeof(struct vring_desc); j++) + buffer_len +=3D indir_desc[j].len; + } + + *len =3D buffer_len; + } + } else { + last_used =3D (vq->last_used_idx & (vq->split.vring.num - 1)); + i =3D virtio32_to_cpu(_vq->vdev, + vq->split.vring.used->ring[last_used].id); + *len =3D virtio32_to_cpu(_vq->vdev, + vq->split.vring.used->ring[last_used].len); + } =20 if (unlikely(i >=3D vq->split.vring.num)) { BAD_RING(vq, "id %u out of range\n", i); @@ -2236,6 +2271,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int = index, vq->split.avail_flags_shadow =3D 0; vq->split.avail_idx_shadow =3D 0; =20 + vq->split.next_desc_begin =3D 0; + /* No callback? Tell other side not to bother us. */ if (!callback) { vq->split.avail_flags_shadow |=3D VRING_AVAIL_F_NO_INTERRUPT; --=20 2.17.1