From mboxrd@z Thu Jan 1 00:00:00 1970 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 472F6168BD for ; Tue, 18 Jul 2023 20:27:51 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A77AE5 for ; Tue, 18 Jul 2023 13:27:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1689712060; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=UFzQVLD8HSP1RQHiTiX0erd1kVWah51g3weAFxDkVck=; b=KXoxZa1wvh6uJ1R9hnvVbn2hju6/1ONC4zjc+FGKcUEoqZ1A4WLc4zSLkvFP1Zm69KZYq1 kNUBdeK13J2hqLWtGyu5NTl0/Peq5RiHVDD091Rom4LElPasKovh+7j5+WnnR0qKI6XOcK 22kd38IUychA/d10pgrinDALOFZKROU= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-182-v4zqKlGZMsCFNflc1zf8AA-1; Tue, 18 Jul 2023 16:27:39 -0400 X-MC-Unique: v4zqKlGZMsCFNflc1zf8AA-1 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-3fbdd5d09b8so38434205e9.1 for ; Tue, 18 Jul 2023 13:27:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689712058; x=1692304058; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=UFzQVLD8HSP1RQHiTiX0erd1kVWah51g3weAFxDkVck=; b=jn0pfO5S7CeMthnAKYbB3h0HTjfNUd1JDIDhLhGU3e5wwi7m/jPrm+l0aXZjvSTzcb oZ3UxBpTxilf7FDiFc6Q3eiuPvduIs42GA9JDZp1pNOekOx0cPIygxp0/+3Yzvve4gs0 B4X5AocW3jxJEB9poFzFxEDxV2BCiRU2jwF7E63wqgnRxUpbigEpKLtSGEniHlT3Izcd EkDvGb35sEuarCvwvEIhX/U8S6x+XNr5DFV7RqTqsmqVhEOlhugJQgb3bu25C8ES8zmd 4rjL6o/kkXF6PKn1BsSq+Qq7Kzd+aOd7MZgYBHzYRI1UXLypPiF7Z2IK00HiXjbxP8Ah XaKg== X-Gm-Message-State: ABy/qLazJAqy3lqdQREdhUXUZUdyIUwOkz3w7qytdtCK11/z324OJYwU u1EKxcHd0hNDG594TqiBwFOxS4oYkWsv+MxZ9Hoxmnn7MAo6OBcQRzl7lBRKE71349YuAZhuekt XbbSRQprdUgoKWzYg X-Received: by 2002:adf:f045:0:b0:313:e591:94ec with SMTP id t5-20020adff045000000b00313e59194ecmr13934268wro.67.1689712058007; Tue, 18 Jul 2023 13:27:38 -0700 (PDT) X-Google-Smtp-Source: APBJJlHUSL09uGLyJ1DR1WqntoobKzn63+jF7HDSK0e6I01IxLEjjbrBzLog+jIdJvOcqhUNu9bHBQ== X-Received: by 2002:adf:f045:0:b0:313:e591:94ec with SMTP id t5-20020adff045000000b00313e59194ecmr13934256wro.67.1689712057598; Tue, 18 Jul 2023 13:27:37 -0700 (PDT) Received: from redhat.com ([2.52.16.41]) by smtp.gmail.com with ESMTPSA id n13-20020adff08d000000b0031433443265sm3305560wro.53.2023.07.18.13.27.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Jul 2023 13:27:36 -0700 (PDT) Date: Tue, 18 Jul 2023 16:27:32 -0400 From: "Michael S. Tsirkin" To: Arseniy Krasnov Cc: Stefan Hajnoczi , Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jason Wang , Bobby Eshleman , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@sberdevices.ru, oxffffaa@gmail.com Subject: Re: [PATCH net-next v2 2/4] vsock/virtio: support to send non-linear skb Message-ID: <20230718162202-mutt-send-email-mst@kernel.org> References: <20230718180237.3248179-1-AVKrasnov@sberdevices.ru> <20230718180237.3248179-3-AVKrasnov@sberdevices.ru> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230718180237.3248179-3-AVKrasnov@sberdevices.ru> X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL, SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Tue, Jul 18, 2023 at 09:02:35PM +0300, Arseniy Krasnov wrote: > For non-linear skb use its pages from fragment array as buffers in > virtio tx queue. These pages are already pinned by 'get_user_pages()' > during such skb creation. > > Signed-off-by: Arseniy Krasnov > Reviewed-by: Stefano Garzarella > --- > net/vmw_vsock/virtio_transport.c | 40 +++++++++++++++++++++++++++----- > 1 file changed, 34 insertions(+), 6 deletions(-) > > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c > index e95df847176b..6cbb45bb12d2 100644 > --- a/net/vmw_vsock/virtio_transport.c > +++ b/net/vmw_vsock/virtio_transport.c > @@ -100,7 +100,9 @@ virtio_transport_send_pkt_work(struct work_struct *work) > vq = vsock->vqs[VSOCK_VQ_TX]; > > for (;;) { > - struct scatterlist hdr, buf, *sgs[2]; > + /* +1 is for packet header. */ > + struct scatterlist *sgs[MAX_SKB_FRAGS + 1]; > + struct scatterlist bufs[MAX_SKB_FRAGS + 1]; > int ret, in_sg = 0, out_sg = 0; > struct sk_buff *skb; > bool reply; > @@ -111,12 +113,38 @@ virtio_transport_send_pkt_work(struct work_struct *work) > > virtio_transport_deliver_tap_pkt(skb); > reply = virtio_vsock_skb_reply(skb); > + sg_init_one(&bufs[out_sg], virtio_vsock_hdr(skb), > + sizeof(*virtio_vsock_hdr(skb))); > + sgs[out_sg] = &bufs[out_sg]; > + out_sg++; > + > + if (!skb_is_nonlinear(skb)) { > + if (skb->len > 0) { > + sg_init_one(&bufs[out_sg], skb->data, skb->len); > + sgs[out_sg] = &bufs[out_sg]; > + out_sg++; > + } > + } else { > + struct skb_shared_info *si; > + int i; > + > + si = skb_shinfo(skb); > + > + for (i = 0; i < si->nr_frags; i++) { > + skb_frag_t *skb_frag = &si->frags[i]; > + void *va = page_to_virt(skb_frag->bv_page); > > - sg_init_one(&hdr, virtio_vsock_hdr(skb), sizeof(*virtio_vsock_hdr(skb))); > - sgs[out_sg++] = &hdr; > - if (skb->len > 0) { > - sg_init_one(&buf, skb->data, skb->len); > - sgs[out_sg++] = &buf; > + /* We will use 'page_to_virt()' for userspace page here, don't put comments after code they refer to, please? > + * because virtio layer will call 'virt_to_phys()' later it will but not always. sometimes it's the dma mapping layer. > + * to fill buffer descriptor. We don't touch memory at > + * "virtual" address of this page. you need to stick "the" in a bunch of places above. > + */ > + sg_init_one(&bufs[out_sg], > + va + skb_frag->bv_offset, > + skb_frag->bv_len); > + sgs[out_sg] = &bufs[out_sg]; > + out_sg++; > + } > } > > ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL); There's a problem here: if there vq is small this will fail. So you really should check free vq s/gs and switch to non-zcopy if too small. > -- > 2.25.1