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=-2.3 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 16630C3A5A4 for ; Fri, 30 Aug 2019 08:15:17 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DA2DE21726 for ; Fri, 30 Aug 2019 08:15:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DA2DE21726 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57088 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i3c3v-0007OF-Tu for qemu-devel@archiver.kernel.org; Fri, 30 Aug 2019 04:15:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39425) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i3c1X-0006Ce-Dz for qemu-devel@nongnu.org; Fri, 30 Aug 2019 04:12:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i3c1V-00055w-WD for qemu-devel@nongnu.org; Fri, 30 Aug 2019 04:12:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54742) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i3c1L-0004LU-PE; Fri, 30 Aug 2019 04:12:36 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9A5C28CF1A3; Fri, 30 Aug 2019 08:12:30 +0000 (UTC) Received: from [10.36.116.105] (ovpn-116-105.ams2.redhat.com [10.36.116.105]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C76905D9E5; Fri, 30 Aug 2019 08:12:19 +0000 (UTC) To: Peter Xu References: <20190730172137.23114-1-eric.auger@redhat.com> <20190730172137.23114-4-eric.auger@redhat.com> <20190815135400.GC8463@xz-x1> <20190830012614.GK8729@xz-x1> From: Auger Eric Message-ID: <016b4d8e-7d65-d9e6-880f-8533e4f7f4af@redhat.com> Date: Fri, 30 Aug 2019 10:12:18 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190830012614.GK8729@xz-x1> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.69]); Fri, 30 Aug 2019 08:12:30 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH for-4.2 v10 03/15] virtio-iommu: Add skeleton X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, kevin.tian@intel.com, mst@redhat.com, tn@semihalf.com, qemu-devel@nongnu.org, alex.williamson@redhat.com, qemu-arm@nongnu.org, jean-philippe@linaro.org, bharat.bhushan@nxp.com, eric.auger.pro@gmail.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Peter, On 8/30/19 3:26 AM, Peter Xu wrote: > On Thu, Aug 29, 2019 at 02:18:42PM +0200, Auger Eric wrote: >> Hi Peter, >> >> First of all, please forgive me for the delay. >> On 8/15/19 3:54 PM, Peter Xu wrote: >>> On Tue, Jul 30, 2019 at 07:21:25PM +0200, Eric Auger wrote: >>>> +static void virtio_iommu_handle_command(VirtIODevice *vdev, VirtQueue *vq) >>>> +{ >>>> + VirtIOIOMMU *s = VIRTIO_IOMMU(vdev); >>>> + struct virtio_iommu_req_head head; >>>> + struct virtio_iommu_req_tail tail; >>> >>> [1] >>> >>>> + VirtQueueElement *elem; >>>> + unsigned int iov_cnt; >>>> + struct iovec *iov; >>>> + size_t sz; >>>> + >>>> + for (;;) { >>>> + elem = virtqueue_pop(vq, sizeof(VirtQueueElement)); >>>> + if (!elem) { >>>> + return; >>>> + } >>>> + >>>> + if (iov_size(elem->in_sg, elem->in_num) < sizeof(tail) || >>>> + iov_size(elem->out_sg, elem->out_num) < sizeof(head)) { >>>> + virtio_error(vdev, "virtio-iommu bad head/tail size"); >>>> + virtqueue_detach_element(vq, elem, 0); >>>> + g_free(elem); >>>> + break; >>>> + } >>>> + >>>> + iov_cnt = elem->out_num; >>>> + iov = g_memdup(elem->out_sg, sizeof(struct iovec) * elem->out_num); >>> >>> Could I ask why memdup is needed here? >> Indeed I don't think it is needed and besides iov is not freed! >> >> I got inspired from hw/net/virtio-net.c. To be honest I don't get why >> the g_memdup is needed there either. The out_sg gets duplicated and >> commands work on the duplicated data and not in place. > > Oh true, I found that it's because of calling of iov_discard_front(). > Please have a look at 771b6ed37e3. Though it seems to me that > virtio-iommu does not truncate iovs so it should not be needed. thanks for the sha1. indeed virtio-iommu does not use iov_discard_front so I shouldn't need it. > >>> >>>> + sz = iov_to_buf(iov, iov_cnt, 0, &head, sizeof(head)); >>>> + if (unlikely(sz != sizeof(head))) { >>>> + tail.status = VIRTIO_IOMMU_S_DEVERR; >>> >>> Do you need to zero the reserved bits to make sure it won't contain >>> garbage? Same question to below uses of tail. >> yes. I initialized tail. >>> >>>> + goto out; >>>> + } >>>> + qemu_mutex_lock(&s->mutex); >>>> + switch (head.type) { >>>> + case VIRTIO_IOMMU_T_ATTACH: >>>> + tail.status = virtio_iommu_handle_attach(s, iov, iov_cnt); >>>> + break; >>>> + case VIRTIO_IOMMU_T_DETACH: >>>> + tail.status = virtio_iommu_handle_detach(s, iov, iov_cnt); >>>> + break; >>>> + case VIRTIO_IOMMU_T_MAP: >>>> + tail.status = virtio_iommu_handle_map(s, iov, iov_cnt); >>>> + break; >>>> + case VIRTIO_IOMMU_T_UNMAP: >>>> + tail.status = virtio_iommu_handle_unmap(s, iov, iov_cnt); >>>> + break; >>>> + default: >>>> + tail.status = VIRTIO_IOMMU_S_UNSUPP; >>>> + } >>>> + qemu_mutex_unlock(&s->mutex); >>>> + >>>> +out: >>>> + sz = iov_from_buf(elem->in_sg, elem->in_num, 0, >>>> + &tail, sizeof(tail)); >>>> + assert(sz == sizeof(tail)); >>>> + >>>> + virtqueue_push(vq, elem, sizeof(tail)); >>> >>> s/tail/head/ (though they are the same size)? >> That's unclear to me. Similarly when checking against virtio-net.c, the >> element is pushed back to the used ring and len is set to the size of >> the status with: >> >> /* >> * Control virtqueue data structures >> * >> * The control virtqueue expects a header in the first sg entry >> * and an ack/status response in the last entry. Data for the >> * command goes in between. >> */ > > I was referencing the balloon code when reading the patch, e.g., > virtio_balloon_handle_output(). Though after I read more carefully I > see that other places are using it as you described. Now I tend to > agree with you, because virtqueue_push() who calls > virtqueue_unmap_sg() used the len to unmap in_sg[] rather than > out_sg[]. So please ignore my previous comment. OK > > (then I'm not sure whether the usage in the balloon code was correct > now...) > >>> >>>> + virtio_notify(vdev, vq); >>>> + g_free(elem); >>>> + } >>>> +} >>> >>> [...] >>> >>>> +static void virtio_iommu_set_features(VirtIODevice *vdev, uint64_t val) >>>> +{ >>>> + VirtIOIOMMU *dev = VIRTIO_IOMMU(vdev); >>>> + >>>> + dev->acked_features = val; >>>> + trace_virtio_iommu_set_features(dev->acked_features); >>>> +} >>>> + >>>> +static const VMStateDescription vmstate_virtio_iommu_device = { >>>> + .name = "virtio-iommu-device", >>>> + .unmigratable = 1, >>> >>> Curious, is there explicit reason to not support migration from the >>> first version? :) >> The state is made of red black trees, lists. For the former there is no >> VMSTATE* ready. I am working on it but I think this should be handled >> separately > > Fair enough. Would you mind to add a similar comment above > unmigratable? sure Thanks! Eric > > Thanks, >