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=-17.7 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 87FE6C4338F for ; Fri, 6 Aug 2021 06:26:49 +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 B0295611C5 for ; Fri, 6 Aug 2021 06:26:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org B0295611C5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:53740 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mBtJf-00031U-Me for qemu-devel@archiver.kernel.org; Fri, 06 Aug 2021 02:26:47 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36472) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mBtIy-0001fP-AS for qemu-devel@nongnu.org; Fri, 06 Aug 2021 02:26:04 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:34886) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mBtIw-0000aq-MU for qemu-devel@nongnu.org; Fri, 06 Aug 2021 02:26:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1628231161; 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=cUEmi5L1+k3WK3DPbfE0IQYdDsQFRFdy3+OuakQvDCI=; b=gAlHBixgsKxpj0ehQ8HhIzSe9lhISRaNq0ZhAnuEIpFPtGrMAB9x8xKrNNTVEF+7xu0dk0 DhWvwzxN68/TJ42/pPu26J46pwzranepoc1T2Jvqtrreg39gDcW8houm9GrzRvxGiZBXES 42/dmYnUkwx3nU8KVkc8q+gVzCVTt0g= Received: from mail-pj1-f71.google.com (mail-pj1-f71.google.com [209.85.216.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-43-Os5yPNgWNkW08djuj56EQw-1; Fri, 06 Aug 2021 02:26:00 -0400 X-MC-Unique: Os5yPNgWNkW08djuj56EQw-1 Received: by mail-pj1-f71.google.com with SMTP id 16-20020a17090a1990b029017582e03c3bso13965781pji.7 for ; Thu, 05 Aug 2021 23:26:00 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=cUEmi5L1+k3WK3DPbfE0IQYdDsQFRFdy3+OuakQvDCI=; b=tFdO6CehEtzXxeCDj7nSHxHjR0SMTjrHhWGie8lbRB5DEvlpKOCeARpgySv6LyyCvW rEkntoKoTwLGBIIb9l40mcx8ITHS2ddo6xMsRckfO02rffZ0y0x5KSJgCwkIiCFXIoOD 8yKOVmQpxCFkxiXxhl2rXllyC0t4WB7/mgUtC2HWnJxJqhR6ZyAhoxgdd1nXhIEiQbgg 5hzCSaaD12HZhMqkq9sHJe/K1bdIjPAH1+/RHLG7BYG1lSCBQ5m4SYpsvg1nNxfvxgW0 aUt7J7g+NOND084str8PBGqKxXuj6q92NWCVuJXhsdBE4qcqSuTLgAABrjlcMR2cibS2 FYfA== X-Gm-Message-State: AOAM533l1CDbmRSzRvPF2nLHII8l3YBAcQjkEHVZ9Dpx/3Wl3DaEDfyk Ul9Fpg4SoMuHQrJq03mWBOYlhvkzhe/8q6QXDtQwMkaWcKv5QuCVlV8S6EmvuKOgYOOVKrflxXl Biole5XpZH5XziZE= X-Received: by 2002:a62:584:0:b029:32e:3b57:a1c6 with SMTP id 126-20020a6205840000b029032e3b57a1c6mr9033101pff.13.1628231159513; Thu, 05 Aug 2021 23:25:59 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyw6hmxlijJJREOJxZ1VnBTugfejrteMWL8asxcwSii9cYjDIIyJBDnVuSW91iWSGneNm+c6A== X-Received: by 2002:a62:584:0:b029:32e:3b57:a1c6 with SMTP id 126-20020a6205840000b029032e3b57a1c6mr9033086pff.13.1628231159285; Thu, 05 Aug 2021 23:25:59 -0700 (PDT) Received: from wangxiaodeMacBook-Air.local ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id w21sm9033871pfq.40.2021.08.05.23.25.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 05 Aug 2021 23:25:58 -0700 (PDT) Subject: Re: [PATCH 1/2] virtio: add a way to disable a queue To: Laurent Vivier , qemu-devel@nongnu.org References: <20210729191910.317114-1-lvivier@redhat.com> <20210729191910.317114-2-lvivier@redhat.com> From: Jason Wang Message-ID: Date: Fri, 6 Aug 2021 14:25:55 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: 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: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.699, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.132, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-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: Juan Quintela , Jens Freimann , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 在 2021/8/2 下午4:42, Laurent Vivier 写道: > On 02/08/2021 06:50, Jason Wang wrote: >> 在 2021/7/30 上午3:19, Laurent Vivier 写道: >>> Add virtio_queue_disable()/virtio_queue_enable() to disable/enable a queue >>> by setting vring.num to 0 (or num_default). >>> This is needed to be able to disable a guest driver from the host side >> >> I suspect this won't work correclty for vhost. > With my test it seems to work with vhost too. So setting 0 will lead -EINVAL to be returned during VHOST_SET_VRING_NUM. I think qemu will warn the failure in this case. What's more important, it's not guaranteed to work for the case of vhost-user or vhost-vDPA. > >> And I believe we should only do this after the per queue enabling/disabling is supported >> by the spec. >> >> (only MMIO support that AFAIK) > I don't want to modify the spec. > > I need something that works without modifying existing (old) drivers. > > The idea is to be able to disable the virtio-net kernel driver from QEMU if the driver is > too old (i.e. it doesn't support STANDBY feature). > > Setting vring.num to 0 forces the kernel driver to exit on error in the probe function. > It's what I want: the device is present but disabled (the driver is not loaded). > > Any other suggestion? I think we should probably disable the device instead of doing it per virtqueue. Thanks > > Thanks, > Laurent > >> Thanks >> >> >>> Signed-off-by: Laurent Vivier >>> --- >>>   include/hw/virtio/virtio.h |  2 ++ >>>   hw/virtio/virtio.c         | 10 ++++++++++ >>>   2 files changed, 12 insertions(+) >>> >>> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h >>> index 8bab9cfb7507..6a3f71b4cd88 100644 >>> --- a/include/hw/virtio/virtio.h >>> +++ b/include/hw/virtio/virtio.h >>> @@ -251,6 +251,8 @@ void virtio_config_modern_writel(VirtIODevice *vdev, >>>                                    uint32_t addr, uint32_t data); >>>   void virtio_queue_set_addr(VirtIODevice *vdev, int n, hwaddr addr); >>>   hwaddr virtio_queue_get_addr(VirtIODevice *vdev, int n); >>> +void virtio_queue_enable(VirtIODevice *vdev, int n); >>> +void virtio_queue_disable(VirtIODevice *vdev, int n); >>>   void virtio_queue_set_num(VirtIODevice *vdev, int n, int num); >>>   int virtio_queue_get_num(VirtIODevice *vdev, int n); >>>   int virtio_queue_get_max_num(VirtIODevice *vdev, int n); >>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c >>> index 874377f37a70..fa5228c1a2d6 100644 >>> --- a/hw/virtio/virtio.c >>> +++ b/hw/virtio/virtio.c >>> @@ -2244,6 +2244,16 @@ void virtio_queue_set_rings(VirtIODevice *vdev, int n, hwaddr desc, >>>       virtio_init_region_cache(vdev, n); >>>   } >>>   +void virtio_queue_disable(VirtIODevice *vdev, int n) >>> +{ >>> +    vdev->vq[n].vring.num = 0; >>> +} >>> + >>> +void virtio_queue_enable(VirtIODevice *vdev, int n) >>> +{ >>> +    vdev->vq[n].vring.num = vdev->vq[n].vring.num_default; >>> +} >>> + >>>   void virtio_queue_set_num(VirtIODevice *vdev, int n, int num) >>>   { >>>       /* Don't allow guest to flip queue between existent and