From patchwork Fri Jun 2 09:22:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xuan Zhuo X-Patchwork-Id: 13264975 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 5C36A17748; Fri, 2 Jun 2023 09:22:21 +0000 (UTC) Received: from out30-98.freemail.mail.aliyun.com (out30-98.freemail.mail.aliyun.com [115.124.30.98]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E757E4C; Fri, 2 Jun 2023 02:22:19 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045170;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=14;SR=0;TI=SMTPD_---0Vk9M5tA_1685697733; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0Vk9M5tA_1685697733) by smtp.aliyun-inc.com; Fri, 02 Jun 2023 17:22:14 +0800 From: Xuan Zhuo To: virtualization@lists.linux-foundation.org Cc: "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , netdev@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH vhost v10 06/10] virtio_ring: packed-detach: support return dma info to driver Date: Fri, 2 Jun 2023 17:22:02 +0800 Message-Id: <20230602092206.50108-7-xuanzhuo@linux.alibaba.com> X-Mailer: git-send-email 2.32.0.3.g01195cf9f In-Reply-To: <20230602092206.50108-1-xuanzhuo@linux.alibaba.com> References: <20230602092206.50108-1-xuanzhuo@linux.alibaba.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Git-Hash: 3bf1b1dbeb8a X-Spam-Status: No, score=-9.9 required=5.0 tests=BAYES_00, ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE,UNPARSEABLE_RELAY,USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Under the premapped mode, the driver needs to unmap the DMA address after receiving the buffer. The virtio core records the DMA address, so the driver needs a way to get the dma info from the virtio core. A straightforward approach is to pass an array to the virtio core when calling virtqueue_get_buf(). However, it is not feasible when there are multiple DMA addresses in the descriptor chain, and the array size is unknown. To solve this problem, a helper be introduced. After calling virtqueue_get_buf(), the driver can call the helper to retrieve a dma info. If the helper function returns -EAGAIN, it means that there are more DMA addresses to be processed, and the driver should call the helper function again. To keep track of the current position in the chain, a cursor must be passed to the helper function, which is initialized by virtqueue_get_buf(). Some processes are done inside this helper, so this helper MUST be called under the premapped mode. Signed-off-by: Xuan Zhuo --- drivers/virtio/virtio_ring.c | 105 ++++++++++++++++++++++++++++++++--- include/linux/virtio.h | 9 ++- 2 files changed, 103 insertions(+), 11 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index cdc4349f6066..cbc22daae7e1 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -1695,8 +1695,85 @@ static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq) return needs_kick; } +static void detach_cursor_init_packed(struct vring_virtqueue *vq, + struct virtqueue_detach_cursor *cursor, u16 id) +{ + struct vring_desc_state_packed *state = NULL; + u32 len; + + state = &vq->packed.desc_state[id]; + + /* Clear data ptr. */ + state->data = NULL; + + vq->packed.desc_extra[state->last].next = vq->free_head; + vq->free_head = id; + vq->vq.num_free += state->num; + + /* init cursor */ + cursor->curr = id; + cursor->done = 0; + cursor->pos = 0; + + if (vq->packed.desc_extra[id].flags & VRING_DESC_F_INDIRECT) { + len = vq->split.desc_extra[id].len; + + cursor->num = len / sizeof(struct vring_packed_desc); + cursor->indirect = true; + + vring_unmap_extra_packed(vq, &vq->packed.desc_extra[id]); + } else { + cursor->num = state->num; + cursor->indirect = false; + } +} + +static int virtqueue_detach_packed(struct virtqueue *_vq, struct virtqueue_detach_cursor *cursor, + dma_addr_t *addr, u32 *len, enum dma_data_direction *dir) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + + if (unlikely(cursor->done)) + return -EINVAL; + + if (!cursor->indirect) { + struct vring_desc_extra *extra; + + extra = &vq->packed.desc_extra[cursor->curr]; + cursor->curr = extra->next; + + *addr = extra->addr; + *len = extra->len; + *dir = (extra->flags & VRING_DESC_F_WRITE) ? DMA_FROM_DEVICE : DMA_TO_DEVICE; + + if (++cursor->pos == cursor->num) { + cursor->done = true; + return 0; + } + } else { + struct vring_packed_desc *indir_desc, *desc; + u16 flags; + + indir_desc = vq->packed.desc_state[cursor->curr].indir_desc; + desc = &indir_desc[cursor->pos]; + + flags = le16_to_cpu(desc->flags); + *addr = le64_to_cpu(desc->addr); + *len = le32_to_cpu(desc->len); + *dir = (flags & VRING_DESC_F_WRITE) ? DMA_FROM_DEVICE : DMA_TO_DEVICE; + + if (++cursor->pos == cursor->num) { + kfree(indir_desc); + cursor->done = true; + return 0; + } + } + + return -EAGAIN; +} + static void detach_buf_packed(struct vring_virtqueue *vq, - unsigned int id, void **ctx) + unsigned int id) { struct vring_desc_state_packed *state = NULL; struct vring_packed_desc *desc; @@ -1736,8 +1813,6 @@ static void detach_buf_packed(struct vring_virtqueue *vq, } kfree(desc); state->indir_desc = NULL; - } else if (ctx) { - *ctx = state->indir_desc; } } @@ -1768,7 +1843,8 @@ static bool more_used_packed(const struct vring_virtqueue *vq) static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq, unsigned int *len, - void **ctx) + void **ctx, + struct virtqueue_detach_cursor *cursor) { struct vring_virtqueue *vq = to_vvq(_vq); u16 last_used, id, last_used_idx; @@ -1808,7 +1884,14 @@ static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq, /* detach_buf_packed clears data, so grab it now. */ ret = vq->packed.desc_state[id].data; - detach_buf_packed(vq, id, ctx); + + if (!vq->indirect && ctx) + *ctx = vq->packed.desc_state[id].indir_desc; + + if (vq->premapped) + detach_cursor_init_packed(vq, cursor, id); + else + detach_buf_packed(vq, id); last_used += vq->packed.desc_state[id].num; if (unlikely(last_used >= vq->packed.vring.num)) { @@ -1960,7 +2043,8 @@ static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq) return true; } -static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq) +static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq, + struct virtqueue_detach_cursor *cursor) { struct vring_virtqueue *vq = to_vvq(_vq); unsigned int i; @@ -1973,7 +2057,10 @@ static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq) continue; /* detach_buf clears data, so grab it now. */ buf = vq->packed.desc_state[i].data; - detach_buf_packed(vq, i, NULL); + if (vq->premapped) + detach_cursor_init_packed(vq, cursor, i); + else + detach_buf_packed(vq, i); END_USE(vq); return buf; } @@ -2458,7 +2545,7 @@ void *virtqueue_get_buf_ctx(struct virtqueue *_vq, unsigned int *len, { struct vring_virtqueue *vq = to_vvq(_vq); - return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx) : + return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx, NULL) : virtqueue_get_buf_ctx_split(_vq, len, ctx, NULL); } EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx); @@ -2590,7 +2677,7 @@ void *virtqueue_detach_unused_buf(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); - return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq) : + return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq, NULL) : virtqueue_detach_unused_buf_split(_vq, NULL); } EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf); diff --git a/include/linux/virtio.h b/include/linux/virtio.h index eb4a4e4329aa..7f137c7a9034 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -43,8 +43,13 @@ struct virtqueue_detach_cursor { unsigned done:1; unsigned hole:14; - /* for split head */ - unsigned head:16; + union { + /* for split head */ + unsigned head:16; + + /* for packed id */ + unsigned curr:16; + }; unsigned num:16; unsigned pos:16; };