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=-15.2 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 CBEDEC433DB for ; Thu, 4 Feb 2021 03:17:09 +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 2829E64F43 for ; Thu, 4 Feb 2021 03:17:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2829E64F43 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]:48386 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l7V8m-0000yv-3i for qemu-devel@archiver.kernel.org; Wed, 03 Feb 2021 22:17:08 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:60014) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l7V6l-0008L9-5U for qemu-devel@nongnu.org; Wed, 03 Feb 2021 22:15:03 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:36116) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l7V6h-0005bm-Vn for qemu-devel@nongnu.org; Wed, 03 Feb 2021 22:15:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612408498; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=M3nSOkJ4+1o5Qg644rs4bNZhLAp4rDjJyu++BsMPd2E=; b=Og69fVfqXAqDhPwPJd30w+YTfzbk+Vo5z97XAwQctXbLmfQHBH9FKrsSM6/LITbiBGcDIB bDsRFX+/KDDi79v3zj9OnRCfjsqw5SUqOF6RajMFldEJVsTTo6fepxoVGozC1SnCa1ma/7 HfLDzFCch/LsETOnM8VxbCzOybvQoh0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-253-2eaBbwwBM96jJ8AtkWZVOA-1; Wed, 03 Feb 2021 22:14:55 -0500 X-MC-Unique: 2eaBbwwBM96jJ8AtkWZVOA-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 49337107ACE3; Thu, 4 Feb 2021 03:14:53 +0000 (UTC) Received: from [10.72.14.1] (ovpn-14-1.pek2.redhat.com [10.72.14.1]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9C1C25D9C0; Thu, 4 Feb 2021 03:14:42 +0000 (UTC) Subject: Re: [RFC 05/10] vhost: Add vhost_dev_from_virtio To: Eugenio Perez Martin References: <20210129205415.876290-1-eperezma@redhat.com> <20210129205415.876290-6-eperezma@redhat.com> From: Jason Wang Message-ID: Date: Thu, 4 Feb 2021 11:14:41 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jasowang@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Received-SPF: pass client-ip=216.205.24.124; envelope-from=jasowang@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.539, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.178, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Rob Miller , Parav Pandit , Juan Quintela , "Michael S. Tsirkin" , qemu-level , Markus Armbruster , Harpreet Singh Anand , Xiao W Wang , Stefan Hajnoczi , Eli Cohen , virtualization@lists.linux-foundation.org, Michael Lilja , Jim Harford , Stefano Garzarella Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2021/2/2 下午6:17, Eugenio Perez Martin wrote: > On Tue, Feb 2, 2021 at 4:31 AM Jason Wang wrote: >> >> On 2021/2/1 下午4:28, Eugenio Perez Martin wrote: >>> On Mon, Feb 1, 2021 at 7:13 AM Jason Wang wrote: >>>> On 2021/1/30 上午4:54, Eugenio Pérez wrote: >>>>> Signed-off-by: Eugenio Pérez >>>>> --- >>>>> include/hw/virtio/vhost.h | 1 + >>>>> hw/virtio/vhost.c | 17 +++++++++++++++++ >>>>> 2 files changed, 18 insertions(+) >>>>> >>>>> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h >>>>> index 4a8bc75415..fca076e3f0 100644 >>>>> --- a/include/hw/virtio/vhost.h >>>>> +++ b/include/hw/virtio/vhost.h >>>>> @@ -123,6 +123,7 @@ uint64_t vhost_get_features(struct vhost_dev *hdev, const int *feature_bits, >>>>> void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits, >>>>> uint64_t features); >>>>> bool vhost_has_free_slot(void); >>>>> +struct vhost_dev *vhost_dev_from_virtio(const VirtIODevice *vdev); >>>>> >>>>> int vhost_net_set_backend(struct vhost_dev *hdev, >>>>> struct vhost_vring_file *file); >>>>> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c >>>>> index 28c7d78172..8683d507f5 100644 >>>>> --- a/hw/virtio/vhost.c >>>>> +++ b/hw/virtio/vhost.c >>>>> @@ -61,6 +61,23 @@ bool vhost_has_free_slot(void) >>>>> return slots_limit > used_memslots; >>>>> } >>>>> >>>>> +/* >>>>> + * Get the vhost device associated to a VirtIO device. >>>>> + */ >>>>> +struct vhost_dev *vhost_dev_from_virtio(const VirtIODevice *vdev) >>>>> +{ >>>>> + struct vhost_dev *hdev; >>>>> + >>>>> + QLIST_FOREACH(hdev, &vhost_devices, entry) { >>>>> + if (hdev->vdev == vdev) { >>>>> + return hdev; >>>>> + } >>>>> + } >>>>> + >>>>> + assert(hdev); >>>>> + return NULL; >>>>> +} >>>> I'm not sure this can work in the case of multiqueue. E.g vhost-net >>>> multiqueue is a N:1 mapping between vhost devics and virtio devices. >>>> >>>> Thanks >>>> >>> Right. We could add an "vdev vq index" parameter to the function in >>> this case, but I guess the most reliable way to do this is to add a >>> vhost_opaque value to VirtQueue, as Stefan proposed in previous RFC. >> >> So the question still, it looks like it's easier to hide the shadow >> virtqueue stuffs at vhost layer instead of expose them to virtio layer: >> >> 1) vhost protocol is stable ABI >> 2) no need to deal with virtio stuffs which is more complex than vhost >> >> Or are there any advantages if we do it at virtio layer? >> > As far as I can tell, we will need the virtio layer the moment we > start copying/translating buffers. > > In this series, the virtio dependency can be reduced if qemu does not > check the used ring _F_NO_NOTIFY flag before writing to irqfd. It > would enable packed queues and IOMMU immediately, and I think the cost > should not be so high. In the previous RFC this check was deleted > later anyway, so I think it was a bad idea to include it from the start. I am not sure I understand here. For vhost, we can still do anything we want, e.g accessing guest memory etc. Any blocker that prevent us from copying/translating buffers? (Note that qemu will propagate memory mappings to vhost). Thanks > > > > > >> Thanks >> >> >>> I need to take this into account in qmp_x_vhost_enable_shadow_vq too. >>> >>>>> + >>>>> static void vhost_dev_sync_region(struct vhost_dev *dev, >>>>> MemoryRegionSection *section, >>>>> uint64_t mfirst, uint64_t mlast, >