From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1F5BC43331 for ; Fri, 6 Sep 2019 05:18:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D1E2206BB for ; Fri, 6 Sep 2019 05:18:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392341AbfIFFSu (ORCPT ); Fri, 6 Sep 2019 01:18:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60248 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732721AbfIFFSu (ORCPT ); Fri, 6 Sep 2019 01:18:50 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id F100F18C891C; Fri, 6 Sep 2019 05:18:49 +0000 (UTC) Received: from sirius.home.kraxel.org (ovpn-117-72.ams2.redhat.com [10.36.117.72]) by smtp.corp.redhat.com (Postfix) with ESMTP id 14E1D60872; Fri, 6 Sep 2019 05:18:48 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 42172753F; Fri, 6 Sep 2019 07:18:47 +0200 (CEST) Date: Fri, 6 Sep 2019 07:18:47 +0200 From: Gerd Hoffmann To: David Riley Cc: dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org, David Airlie , Daniel Vetter , Gurchetan Singh , =?utf-8?B?U3TDqXBoYW5l?= Marchesin , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] drm/virtio: Use vmalloc for command buffer allocations. Message-ID: <20190906051847.75mj4772nqwdper6@sirius.home.kraxel.org> References: <20190829212417.257397-1-davidriley@chromium.org> <20190905220008.75488-1-davidriley@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190905220008.75488-1-davidriley@chromium.org> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.70]); Fri, 06 Sep 2019 05:18:50 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > +/* How many bytes left in this page. */ > +static unsigned int rest_of_page(void *data) > +{ > + return PAGE_SIZE - offset_in_page(data); > +} Not needed. > +/* Create sg_table from a vmalloc'd buffer. */ > +static struct sg_table *vmalloc_to_sgt(char *data, uint32_t size, int *sg_ents) > +{ > + int nents, ret, s, i; > + struct sg_table *sgt; > + struct scatterlist *sg; > + struct page *pg; > + > + *sg_ents = 0; > + > + sgt = kmalloc(sizeof(*sgt), GFP_KERNEL); > + if (!sgt) > + return NULL; > + > + nents = DIV_ROUND_UP(size, PAGE_SIZE) + 1; Why +1? > + ret = sg_alloc_table(sgt, nents, GFP_KERNEL); > + if (ret) { > + kfree(sgt); > + return NULL; > + } > + > + for_each_sg(sgt->sgl, sg, nents, i) { > + pg = vmalloc_to_page(data); > + if (!pg) { > + sg_free_table(sgt); > + kfree(sgt); > + return NULL; > + } > + > + s = rest_of_page(data); > + if (s > size) > + s = size; vmalloc memory is page aligned, so: s = min(PAGE_SIZE, size); > + sg_set_page(sg, pg, s, offset_in_page(data)); Offset is always zero. > + > + size -= s; > + data += s; > + *sg_ents += 1; sg_ents isn't used anywhere. > + > + if (size) { > + sg_unmark_end(sg); > + } else { > + sg_mark_end(sg); > + break; > + } That looks a bit strange. I guess you need only one of the two because the other is the default? > static int virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev, > struct virtio_gpu_vbuffer *vbuf, > struct virtio_gpu_ctrl_hdr *hdr, > struct virtio_gpu_fence *fence) > { > struct virtqueue *vq = vgdev->ctrlq.vq; > + struct scatterlist *vout = NULL, sg; > + struct sg_table *sgt = NULL; > int rc; > + int outcnt = 0; > + > + if (vbuf->data_size) { > + if (is_vmalloc_addr(vbuf->data_buf)) { > + sgt = vmalloc_to_sgt(vbuf->data_buf, vbuf->data_size, > + &outcnt); > + if (!sgt) > + return -ENOMEM; > + vout = sgt->sgl; > + } else { > + sg_init_one(&sg, vbuf->data_buf, vbuf->data_size); > + vout = &sg; > + outcnt = 1; outcnt must be set in both cases. > +static int virtio_gpu_queue_ctrl_buffer(struct virtio_gpu_device *vgdev, > + struct virtio_gpu_vbuffer *vbuf) > +{ > + return virtio_gpu_queue_fenced_ctrl_buffer(vgdev, vbuf, NULL, NULL); > +} Changing virtio_gpu_queue_ctrl_buffer to call virtio_gpu_queue_fenced_ctrl_buffer should be done in a separate patch. cheers, Gerd